#ShootYourShot: The Materials Science of Film Photography

It’s Wisdom Wednesday! Or is it… #WayBackWednesday?

These days sure make one think: had it not been for COVID-19, most of us would be at different vacation places now. Of course, snapping and posting pictures on social media is an integral part of this ritual, right?

Surely everyone noticed the influx of classy, aesthetic photos recently. These snapshots, while capturing sceneries and portraits of this time, seem to give off a retro and nostalgic vibe. In this age of digital and mirrorless cameras, a different photography tool is making a comeback: the film camera.

More than the device itself, the core of film photography lies on the film itself. The long reels of plastic sheets rolled inside those small black cartridges are made up of various protective coatings, a thick transparent film base, and a light-sensitive emulsion layer.

The thickest layer is the base, which is about 0.025 mm thick. It serves as the support platform for the emulsion layers. Film companies like Kodak have implemented cellulose triacetate as a polymer of choice for the base, replacing the chemically unstable cellulose nitrate. However, polyesters such as PET have been likewise used as these have longer storage lives, better chemical stability, and higher mechanical properties.

Perhaps the most important part would be the emulsion, which is the imaging layer. This light-sensitive stratum consists of imaging components suspended in a special binder made up of gelatin. These imaging elements include sub-micron sized crystals of silver halides (AgX, where X = F, Cl, Br) decorated with organic molecules known as color couplers (aka spectral sensitizers) at the grain surface.

Color couplers are the ones that impart color on your film image. In a color film, there are three separate layers of color couplers. Each of these are sensitive to light of the same color, thus producing the complementary CMY dyes. That is, cyan, magenta, and yellow come from the red, green, and blue-sensitive layers, respectively.

When you press that shutter button, you allow light to pass through and reach the film. The incident light, composed of photons, sensitizes the color couplers first. This prompts the couplers to eject an electron called a photoelectron.

Now, the photoelectron interacts with the AgX crystal by “disturbing” its electronic structure. The silver species in AgX, the cation Ag⁺, lacks an electron. Thus, the photoelectron fills this gap to convert Ag⁺ into Ag, albeit an unstable one. In the end, you now have a chemical trace or “latent” image from sensitized AgX crystals and color couplers. These are termed as such since the image can’t be detected yet until the film is developed.

An alkaline developing solution is then introduced to the film to fully convert (reduce) Ag⁺ to Ag. The oxidized developer, on the other hand, reacts with the sensitized color couplers to produce the CMY dyes. The developing process is then stopped by an acidic solution called a stop bath to neutralize the developer.

A solution called hypo (or fixer) makes the image permanent on the film by dissolving any remaining AgX crystals. The negative image (since it is in a negative pattern) is then printed on photo paper by shining light through the negative, thus creating the positive print.

Perhaps one of the reasons why analog photos give off that rustic, classy vibe is because of the grain. Grains are a natural part of film as it arises from the AgX crystals. However, the size of the grains on pictures is dependent on the photographic sensitivity of the film, otherwise known as “speed”. This is reflected on the film’s ISO rating.

For dim lighting conditions or fast-moving objects, a more light-sensitive bunch (higher ISO) of AgX crystals are needed. Thus, larger grains are embedded in the emulsion. Of course, upon developing the film, the grains would likewise be more prominent on the final picture. If it can be avoided, a slower film—that is, smaller AgX grains—should be used. This is perfect especially for portrait shots where natural lighting is abundant. It is said that for general usage, an ISO 200 film would be suitable to avoid highly grainy images.

Film photographs, with their classy vibe, and digital photographs, for all their crisp, high-resolution glory, are both undoubtedly an integral part of our lives as social beings. No matter the format, we take pictures to capture that one special moment. These snapshots of ours tell a story—each photograph a part of our long journey.

In the end, just always #ShootYourShot, and create your own story of a thousand words.

References:

[1]   C. Woodford, “35mm Film Cameras,” ExplainThatStuff, 2020. [Online]. Available: https://www.explainthatstuff.com/how-film-cameras-work.html. [Accessed: 25-May-2020].

[2]   C. Woodworth, “How Photographic Film Works,” How Stuff Works, 2000. [Online]. Available: https://electronics.howstuffworks.com/film1.htm. [Accessed: 25-May-2020].

[3]   M. Yang, “How Stuff Works: The Science of Film Photography,” The Tartan, 2019. [Online]. Available: https://thetartan.org/2019/2/18/scitech/how-stuff-works. [Accessed: 25-May-2020].

[4]   “Everything You Need to Know About Film Grain and Pixelation,” Richard Photo Lab. [Online]. Available: https://www.richardphotolab.com/blog/post/film-grain-and-pixelation. [Accessed: 26-May-2020].

[5]    “Film Structure,” Kodak. [Online]. Available: https://www.kodak.com/uploadedfiles/motion/US_plugins_acrobat_en_motion_newsletters_filmEss_04_How-film-makes-image.pdf. [Accessed: 25-May-2020].

Content by: Karl Alvarez
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Copper IUDs

It’s Wisdom Wednesday!

The metallic properties of copper do not cease to amaze! From our last Wisdom Wednesday, we learned about its antibacterial properties, making it a promising component for most surfaces we interact with. However, there is yet another amazing feat of copper that’s been gaining traction in the recent years, and that is preventing pregnancy!

Yes, you read right! Copper adds contraception in its long list of applications.

Copper Intrauterine Devices (IUDs) are a non-hormonal birth control option that is long-term and reversible. IUDs are a form of contraceptive that is directly inserted into the uterus to prevent pregnancy. Birth control can either be hormonal or non-hormonal, with the former using hormones—like in birth control pills—to control ovulation. It is long-term because it can be effective for up to 12 years, and reversible because it can be removed at any time, with no adverse effect on fertility.

Both hormonal and non-hormonal IUDs induce a response from our immune system that increases the white blood cells due to the presence of a foreign object. This response attacks foreign cells in the body, which includes sperm. Additionally, the copper ions in the IUD aid with contraception mainly by affecting sperm motility and acrosomal reaction. Motility is the ability of sperm to move using its own cellular energy, and the acrosomal reaction is a change the sperm cell undergoes to be able to go through the egg’s membrane and fertilize it. This is copper’s spermicidal effect. 

It is also possible that copper is an ovicidal agent, having similar effects to egg cells as it does to sperm, impairing it from developing further even if fertilized. The white blood cells from the immune response also make the uterus a hostile environment that prevents implantation if ever an egg is fertilized. 

IUDs are more than 99% effective at preventing pregnancy, largely because it has less instances for human error. Birth control like hormonal pills or condoms are required to be used correctly every time, slightly lessening their success rate. The copper IUD is a good option for women who prefer not to use hormonal birth control or who cannot use them due to medical reasons. 

It can effectively prevent pregnancy up to 12 years upon insertion yet it can be removed at any time. The copper IUD can also be used as emergency contraception, much like the Plan B pill or the Yutzpe method, within up to 5 days after unprotected sex and it is 99.9% effective in preventing pregnancy, with the added bonus of long-term use. 

Some side effects of the copper IUD however mainly affect periods. There may be spotting, irregularity, cramping, and periods may be longer or heavier. Unfortunately, despite the multifaceted nature of copper, IUDs are not a one-stop-shop solution to everything related to contraception. It is important to note however, that IUDs cannot prevent STIs. We’re gonna have to rely on good ol’ fashioned condoms for that. 

References:

[1] Lotke, Pamela S. Contraception, An Issue of Obstetrics and Gynecology Clinics. Elsevier, 2016.

[2] “Non-Hormonal IUDs.” Planned Parenthood. Accessed May 20, 2020. https://www.plannedparenthood.org/learn/birth-control/iud/non-hormonal-copper-iud.

[3] “The Embryo Project Encyclopedia.” Copper Intrauterine Device (IUD) | The Embryo Project Encyclopedia. Accessed May 20, 2020. https://embryo.asu.edu/pages/copper-intrauterine-device-iud.

[4] “What Is the Effectiveness of the IUD?” Planned Parenthood. Accessed May 20, 2020. https://www.plannedparenthood.org/learn/birth-control/iud/how-effective-are-iuds.

Content by: Angel Reyes
Design by: Claire Natividad

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Antimicrobial Properties of Copper

It’s Wisdom Wednesday!

Copper possesses numerous applications for electronics (e.g. wirings) because of its superior electrical and thermal conductivity. Since it’s also non-corrosive, it’s used in plumbing, kitchenware, and construction. These properties are first to usually come to mind when we talk about this metal but it also boasts a unique attribute: antimicrobial properties. 

Throughout history, people have observed this property of copper and used it accordingly. The earliest recorded use of copper as an antiseptic was in Egypt around 2000 BCE. It was used to clean wounds and sterilize water. Ancient Greeks and Romans also utilized it to treat diseases and wounds, and used it as cookware to limit the spread of disease. 

Furthermore, Hindus traditionally use copper, brass, and silver to contain Gangajal (water from the Ganges River) to keep the water clean. Through the United States Westward Expansion, settlers also used to put copper coins in water barrels to preserve potable water. This was also done by Japanese soldiers in the Second World War to prevent infection.

The time it takes for copper to completely sanitize its surface varies from different species and strains of the microorganism, temperature, and concentration of copper in alloys. It has proved to be reliable on eliminating E. coli, a highly infectious bacteria, with a 99.9% rate within 1-2 hours at room temperature. Its efficiency is significantly lowered down at lower temperatures which can take up to 4 1/2 hours at near-freezing temperature. This varies within other bacteria in which some only take a minute or seconds to be killed while bacteria such as M. tuberculosis takes 5-15 days to be destroyed. 

On the other hand, copper alloys kill E. coli within 60-270 mins at room temperature and 180-360 mins at lower temperatures. Copper-Nickel alloy is one of the favored materials for surfaces because of its durability and corrosion resistance. Currently, there are 400 copper mixtures indicated by the U.S. Environmental Protection Agency which can remove 6 infectious bacteria usually found in hospitals.

Moreover, SARS-CoV-2’s, the virus causing COVID-19, persistence on copper surfaces is similar to SARS-CoV-1 which is only roughly 4 hours, compared to other materials that could take up to several days. 

How the ability of copper to eliminate microorganisms is still not perfectly clarified but multiple mechanisms explain this property. Due to copper’s reaction to oxygen, it creates cuprous oxide (Cu2O) which is sufficiently reactive to agitate microorganisms. Another explanation would be the reaction of copper to oxygen, lipids, and proteins in a microorganism’s cell wall, ultimately killing it. 

When a microorganism’s cell wall is damaged, especially for bacteria, it tries to survive by pulling materials from its environment and pushing out unnecessary elements. And, when copper ions enter the microorganism, it attacks the essential bacterial components which makes it toxic for microorganisms.

Through history, research, and clinical trials, copper has proved itself to be a good material not only for the traditional applications we know. Japan and Korea have developed copper fiber sheets and copper-ion infused masks to fight SARS-CoV-2 respectively. It could also help in keeping frequently touched surfaces clean such as doorknobs, faucets, elevator buttons, etc. Currency made of copper such as the 1995 Bangko Sentral ng Pilipinas five peso coin could also prove to be essential to further limit the spread of disease from daily transactions.

In this time of a global pandemic, it is now more important than ever that we seek to understand and utilize the unique properties of materials such as copper to help aid in society’s transition back to a state of normalcy and to reduce the toll that such calamities may cause us in the future.

References:

[1] Bangko Sentral ng Pilipinas, (2015). BSP Coin Series. http://www.bsp.gov.ph/bspnotes/curr_bsp_coins.asp

[2] Borkow, G. and Gabbay J., (2009, September).  Copper, An Ancient Remedy Returning to Fight Microbial, Fungal and Viral Infections. https://www.researchgate.net/publication/233589535_Copper_An_Ancient_Remedy_Returning_to_Fight_Microbial_Fungal_and_Viral_Infections

[3] Copper Development Association Inc., (n.d.). Antimicrobial Properties. https://www.copper.org/applications/marine/cuni/properties/antimicrobial/

[4] van Doremalen, N., et al. (2020) Aerosol and surface stability of HCoV-19 (SARS-CoV-2) compared to SARS-CoV-1. The New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMc2004973

[5] Grass, G., Rensing, C., and Solioz, M., (2010, December 30). Metallic Copper as an Antimicrobial Surface. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3067274/#r8

[6] Hee-seok, C., and Kim, M. (2020, April 27). Korean startup develops sterilization mask that kills virus on mask surface.  https://pulsenews.co.kr/view.php?year=2020&no=436221

[7] Konieczny, J. and Rdzawski, Z., (2012, August). Antibacterial properties of copper and its alloys. https://www.researchgate.net/publication/235430943_Antibacterial_properties_of_copper_and_its_alloys

[8] Michioka, M. (2020, April 10). East Japan venture develops copper fiber sheet that hastens virus particle inactivation. https://mainichi.jp/english/articles/20200410/p2a/00m/0na/002000c

[9] Mitchell, E. (2014, November 12). Just how does copper kill germs? http://blog.eoscu.com/blog/just-how-does-copper-kill-germs

[10] Naafs, M. (2017, August 9). Antimicrobial Properties of Copper and Copper Alloys for Infection Control https://infectioncontrol.tips/2017/08/09/antimicrobial-copper/

[11] Warnes, S., Little, Z., and Keevil, Charles. (2015). Human Coronavirus 229E Remains Infectious on Common Touch Surface Materials. https://www.researchgate.net/figure/Destruction-of-human-coronavirus-viral-genome-on-copper-and-copper-alloy-surfaces-A_fig5_283685229

Content by: Joshua Brian B. Agoncillo
Design by: Philip Ajon Basat

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NCoV on the Surface: Understanding SARS-CoV-2 through Surface Science

It’s Wisdom Wednesday!           

The New Normal. That’s what they’re calling it now—the massive societal upheaval brought about by a force so minute that nobody saw it coming. SARS-CoV-2 has now become an omnipresent threat to humanity. It may not be airborne, but the virus has been found to persist on surfaces for some time, possibly infecting us easier.

Recently, independent studies published by US and Hong Kong-based researchers have indicated that SARS-CoV-2 can last for up to 4 hours on copper surfaces, 24 hours on cardboard, 2-3 days on stainless steel, and 4 days on paper money. [1-3]

Sure, these results tell us that we can acquire the virus by just touching virtually any infected surface. But haven’t you stopped to think of why stainless steel “harbors” SARS-CoV-2 longer than copper, even though they are both metals? Thankfully, surface science is here to rationalize some of these phenomena!

Examining first the structure of SARS-CoV-2 enables an easier understanding of the underlying surface science concepts. The said virus, like most coronaviruses, has four essential structural proteins: the membrane (M), spike (S), envelope (E), and nucleocapsid (N) proteins. The M protein, found at the surface of the virus, is the most abundant glycoprotein among coronaviruses and is believed to be related to viral infectivity and membrane fusion. [4]

On a molecular level, these proteins are made up of long chains of amino acids with both positively charged (NH3⁺) and negatively charged (COO^–) side chains. [5] Each protein has a unique combination of amino acids, thus the amount of charged groups vary from one protein to the other. But how do these charges get determined and quantified?

One key electrochemical parameter is the isoelectric point (pI or IEP). IEP pertains to the pH at which the net charge of the analyte (say, the virus) is zero. [5,6] This means that for IEP < 7, the virus in question is essentially negatively charged since the proteins must have more negatively charged side chains to neutralize the high amount of H⁺ present in the solution. Conversely, a IEP > 7 signifies a positive net charge for the virus.

With those said, the M protein is known to have a pI ranging from 9.3-9.9, thereby imparting a positive charge onto the surface of SARS-CoV (1 and 2). [4,7] On the other hand, copper—whether in its ground or oxidized state—has a IEP of 9.5-9.8. Meanwhile, stainless steel has a IEP value ranging from 3-5. Glass has an even lower IEP at around 2.2. [8]

Both the virus and copper have positive surfaces. Therefore, these two would “repel” each other, or at least have the virus “loosely-bound” onto the copper surface. Stainless steel, on the other hand, offers a more favorable interaction with the virus, thus maintaining its viability for longer periods of time.

Apart from electrostatic interactions, the effect of polar groups should also be considered. In this aspect, the M protein has been found out to consist of 40.7% hydrophobic (“water hating”) groups, 4.5% more than the hydrophilic (“water loving”) groups. [4]

Remember “like dissolves like”? This means there is preferential interaction between two substances of the same polarity. As such, the surface of the virus favors hydrophobic (i.e., non-polar) surfaces like most synthetic polymers. This is the reason why surgical, or even N95 masks should not be used for long periods—its polypropylene outer layer allows accumulation of the virus, and touching it with your bare hands (say, before disposing it) will only increase chances of infection.

Paper-based materials like cardboard, on the other hand, are polar surfaces due to the abundance of OH- groups from its main constituent cellulose. Meanwhile, paper money is technically polar as well, due to its high cotton composition. However, the ink used in printing features on the bill may impart non-polar characteristics. Money is likewise prone to other impurities because of handling.

The concept of surface polarity is also involved in rationalizing why soap and water are more effective at washing away the virus, rather than disinfecting with alcohol alone. The non-polar tail of soap interacts with the viral membrane, forming micelles. The polar heads then allow the micelles to interact with water and be removed during washing.

Of course, other factors, such as surface porosity and environmental factors are at play when studying the surface interactions of viruses. [9] Ultimately, regularly disinfecting surfaces is an effective method of reducing your chances of infection.

Meanwhile, local institutions like the UP Department of Mining, Metallurgical, and Materials Engineering (DMMME) have joined the fray in providing effective surface disinfection. One team aims to use plasma in decontaminating building surfaces, PPEs, and other health equipment.

Plasma—a state of matter consisting of highly ionized gases—produces reactive oxygen and nitrogen species (RONS). RONS are radicalized species that react readily with proteins and nucleic acids, thereby considerably damaging the viral structure. [10-12] Having a mobile plasma treatment apparatus would increase the capability of hospitals to disinfect essential equipment and reduce the possibility of infection of health workers.

These trying times have surely made people more wary of an unseen threat looming over us. If anything, today has shown us the significance of examining phenomena at a surface level. However, delving beneath the surface is as important as it provides a deeper understanding of issues, making us more critical and wiser than we have before.

References:

[1] A. Woodward and S. Gal, “One chart shows how long the coronavirus lives on surfaces like cardboard, plastic, wood, and steel,” Business Insider, 2020. [Online]. Available: https://www.businessinsider.com/coronavirus-lifespan-on-surfaces-graphic-2020-3. [Accessed: 04-May-2020].

[2] N. van Doremalen et al., “Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1,” N. Engl. J. Med., vol. 382, no. 16, pp. 1564–1567, Mar. 2020.

[3] A. W. H. Chin et al., “Stability of SARS-CoV-2 in different environmental conditions,” The Lancet Microbe, vol. 0, no. 0, Apr. 2020.

[4] Y. Hu et al., “The M protein of SARS-CoV: basic structural and immunological properties,” Genomics. Proteomics Bioinformatics, vol. 1, no. 2, pp. 118–130, May 2003.

[5] I. Hunt, “Isoelectric Point, pI,” University of Calgary. [Online]. Available: http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch27/ch27-1-4.html. [Accessed: 05-May-2020].

[6] B. Michen and T. Graule, “Isoelectric points of viruses,” J. Appl. Microbiol., vol. 109, no. 2, pp. 388–397, Aug. 2010.

[7] K. S. Dowluru, “Genomic and Proteomic Studies Using Computational Approaches in SARS Genome,” Apr. 2011.

[8] G. Lefèvre, L. Cerović, S. Milonjić, M. Fédoroff, J. Finne, and A. Jaubertie, “Determination of isoelectric points of metals and metallic alloys by adhesion of latex particles,” J. Colloid Interface Sci., vol. 337, no. 2, pp. 449–455, 2009.

[9] P. Vasickova, I. Pavlik, M. Verani, and A. Carducci, “Issues Concerning Survival of Viruses on Surfaces,” Food Environ. Virol., vol. 2, pp. 24–34, Mar. 2010.

[10] A. Ozcan, “Biochemistry of Reactive Oxygen and Nitrogen Species,” M. O. E.-S. J. T. Gowder, Ed. Rijeka: IntechOpen, 2015, p. Ch. 3.

[11] A. Weidinger and A. V Kozlov, “Biological Activities of Reactive Oxygen and Nitrogen Species: Oxidative Stress versus Signal Transduction,” Biomolecules, vol. 5, no. 2, pp. 472–484, Apr. 2015.

[12] C. N. Paiva and M. T. Bozza, “Are reactive oxygen species always detrimental to pathogens?,” Antioxid. Redox Signal., vol. 20, no. 6, pp. 1000–1037, Feb. 2014.

Content by: Karl Alvarez
Design by: Lila Lu

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Lunar Resources

It’s Wisdom Wednesday!

Have you looked up at the night sky lately and observed the majesty of the moon? This month, we witnessed the biggest and brightest full moon of the year, the pink moon; this week is also the conjunction of the crescent moon and Venus. Despite the ongoing crisis our world has been going through these past months, the brightness and presence of the moon still somehow shed hope down to remind us that there is still light amidst the darkness surrounding us.

Opposite the brightness of the moon however is its dark side that has been permeating mystery humankind ever since. It has only been by the recent exploration of science that we got enough information and are able to study our main satellite. It is indeed true that the moon is a mysterious body even though it is the closest yet to Earth.

The Earth’s moon is the second densest natural satellite in the solar system, second to Jupiter’s Io. The innermost layer is the lunar core with its liquid outer core. It is believed that this dense partly molten core is composed of metallic iron with sulfur and nickel. Exterior to the core are the mantle and crust. During the formation of the layers of the moon, denser materials such as olivine and pyroxene mixed to become the mantle and sank down to the bottom; while lighter minerals such as the anorthositic and plagioclase feldspar, went up to the surface to become the crust. 

The mantle is the thickest layer of the moon, extending up to 50 km below the surface and is believed to be more iron-rich than Earth’s mantle. The lunar crust, on the other hand, is considerably thinner, with a rocky surface covered with piles of charcoal-gray debris called regolith. Regolith is a layer of loose deposits (dust, soil, etc.) and is also present in Earth and other terrestrial planets. In the case of the moon, the regolith came from asteroids and meteorites as they blast into smaller pieces once they collide with the surface. Meanwhile, the extensive lunar maria (aka the dark spots) are plains that are composed of basaltic lava flows formed by ancient volcanic eruptions.

Given the vastness of chemicals and materials that can be found on the moon, these resources are looked at by humans as something that can be used in the future for advancement of science and the benefit of humankind. Ever since the first landing of humans to the moon, we have undeniably looked at the moon differently.

Much of the possible resources that can be extracted from the Moon would be beneficial for energy production, which, of course, is relevant to humans since we harvest mostly non-renewable resources back on Earth. Helium-3, a rare and specific isotope of helium could serve as fuel for nuclear fusion reactors. Another seemingly mundane yet useful resource is the lunar ice abundant in the poles. It can be split into hydrogen and oxygen to be used as a source for rocket propellants; or even serve as a resource for life support for human settlement in the future. 

Similarly, the idea of mining on the moon is not so far off in the imagination of humans in recent years. Through the processes of sintering, hot-pressing, liquification, cast basalt, or 3D printing, the lunar soil can be turned into usable materials. Moreover, with the addition of glass fiber and PETG mixture, the regolith can be strengthened. It then could be mixed together with carbon nanotubes and epoxies for the construction of huge telescope mirrors on the moon, giving us a whole new different perspective in space observation.

More interestingly, elements known to be scarce on Earth exist on the Moon, these are called REMs. REMs include scandium and yttrium which can be utilized for modern electronics (majority of which are produced in China) and even synthesis of new materials. Other more common elements found bountiful on the moon are iron, copper, and aluminum that are important in constructing medical equipment. With these lunar resources, the possibility seems to be endless for humans.

On a different note however, all these prospects do not exist without their downsides. The biggest concern of which is the environmental damage of the discussed activities to both the Moon and the Earth. As the REM being brought to the Earth is mentioned, it is also important to consider the repercussions of which we are not yet fully aware of. The next and also important concern is the ethics surrounding the whole idea of excavating resources from the moon for it will definitely change our perception of the moon as humankind. Surely, alongside the advancement of science is the philosophy of our limits as humans. Is it ethical to allow extraterrestrial resources to the Earth for the benefit of the people? How about its consequences on politics and space law? Such questions exist as we further probe the possibility of us recalibrating our perception on the most valued thing in the night sky.

References:

[1] Burke, J. (2020, February 29). Encyclopaedia Britannica: Lunar Resources. http://www.britannica.com/place/Moon /Lunar-resources

[2] Cain, F. (2008, November 3). What is the Moon Made Of. http://www.universetoday.com/20583/what-is-the-moon-made-of/

[3] NASA Jet Propulsion Lab. (n.d.). Moon Resources and Mining. https://www.jpl.nasa.gov/

[4] NASA Science. (n.d.). Earth’s Moon: In Depth. https://moon.nasa.gov/about/in-depth/

[5] NASA Science. (n.d.). Earth’s Moon: What is Inside The Moon.. https://moon.nasa.gov/about/what-is-inside-the-moon/

[6] Thomson, A. (2009, October 27). Our Changing View of the Moon. http://www.space.com/7338-changing-view-moon.html

Content by: J.L. Rodriguez-Bazarte
Design by: Karl Khumo Calagan

Wisdom Wednesday is brought to you by the UP Materials Science Society.

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Nanopatch

What day is it? It’s another Wisdom Wednesday!

Most of us, though, have probably forgotten that today is Wednesday, and have lost track of time into quarantine. The passage of each day must have been a blur to most of us as we tried to keep up with school requirements, tend to the needs of our family members, or survive a year’s worth of anxiety. 

In our battle against the coronavirus, time is definitely not on our side. As such, there is an urgent demand to develop a medical weapon that would put this grim crisis to an end—a vaccine!

A vaccine is a biological preparation that constitutes a killed or weakened form of a disease-causing microorganism, its toxins or one of its surface proteins. Vaccine therapy stimulates the immune system of the body and provides protection against a future microorganism encounter. However, there are still negative things associated with vaccines, and one of those is needles.

One cannot think of vaccines without the painful memory of closed eyes and gritted teeth, and of a sharp, long needle piercing through the skin. It was in the 1850s when the needle and syringe (N&S) was first invented and since then, it has become the primary device used in vaccination. Typically, vaccines are injected intramuscularly or into the muscle due to its ease of administration. In fact, N&S is one of the conventional drug delivery systems! (There’s hardly any, but it pays to remember the #UsefulDDS) However, this method has several drawbacks. 

Apart from the pain and fear experienced via this needle-based vaccine delivery, the muscles contain relatively lesser antigen-presenting cells (APCs), which are important in generating protective immune responses, thereby requiring a higher dose of vaccine. The stability of vaccine formulations is also heavily dependent upon environmental factors such as temperature and humidity. In temperate and subtropical regions, refrigeration is necessary to maintain efficacy, entailing greater operating costs. In addition, studies show that this so-called “cold chain” is subject to fluctuations, which results in antigen degeneration. 

Microarray patches (MAPs) were then developed to overcome these limitations. They fall under the umbrella term “microneedles” or “microneedle patches”, but have relatively smaller projections. When applied, the projections penetrate the skin, delivering vaccines to the epidermis or dermis, where most APCs (e.g., dermal dendritic cells) reside, evoking a strong immune response similar to the needle-based vaccine delivery, yet with a reduced amount of dosage.

The Nanopatch is an ultra-high density (> 20,000/cm²) MAP with short (30–300 μm) and sharp projections manufactured from silicon chips by deep reactive ion etching (DRIE). Silicon has been recognized as a key material in the manufacture of microstructures and microelectromechanical systems (MEMS) because there is much flexibility in the shapes and sizes that can be readily produced from it. Its considerable mechanical strength also allows it to successfully pierce the skin, facilitating transdermal vaccine delivery (another form of #DDS, folks!)

Unlike a conventional hollow needle, the vaccine is dispensed and dried to the silicon projections via the novel jet-coating approach, instead of drawing it in and releasing it to the desired site of application. This dry-coating technique enhances the thermostability of the Nanopatch, removing the expensive and infrastructure-dependent cold chain, especially in temperate and subtropical regions. Moreover, with the utilization of a separate reusable, hand-held spring-powered, auto-disabling applicator device, specialist training is not expected to be necessary.

To this date, several pre-clinical and clinical trials have been performed, reporting successful deliveries of vaccines against the Inactivated Polio Virus (IPV), Human Papillomavirus (HPV), influenza strains, Measles-Rubella, tetanus toxoid, Chikungunya, and West Nile virus. In investigations involving human subjects, the Nanopatch was also found to be safe, well-tolerable, and preferred over the conventional needle-based vaccine delivery.

Notably, early this April, a microneedle patch intended for vaccine delivery against COVID-19 was tested and has shown promising results in mice. More trials are reportedly underway.

Apart from the delivery of vaccines, the Nanopatch technology boasts of other potential applications. Since the skin is highly vascularized, this transdermal device may also simplify blood collection and processing required for diagnostic assays, and enable rapid minimally invasive diagnosis to be performed immediately. Therefore, rapid screening in infectious diseases is likely to benefit from advances in this area in the future.

The COVID-19 pandemic has utterly revealed the cruel and unkind realities of healthcare, and no romance emanates in draping white hospital blankets over frontliners who succumbed to the deadly virus due to faulty PPEs, or the lack thereof. Our future will now be shaped by the development of new vaccines and immunization or diagnostic practices carried out by changing times. Through these innovative biomedical devices, we hope for the provision of quality healthcare even in low-resource countries, like the Philippines, so that we continue to persist and live meaningfully in the not-so-far new normal.

References:

[1] Chen, X., Fernando, G. J., Crichton, M. L., Flaim, C., Yukiko, S. R., Fairmaid, E. J., … & Brown, L. E. (2011). Improving the reach of vaccines to low-resource regions, with a needle-free vaccine delivery device and long-term thermostabilization. Journal of controlled release, 152(3), 349-355.

[2] Corrie, S., Depelsenaire, A., & Kendall, M. (2012). Introducing the Nanopatch: A skin-based, needle-free vaccine delivery system. Australian Biochemist, 43, 17-20.

[3] Fernando, G. J., Chen, X., Primiero, C. A., Yukiko, S. R., Fairmaid, E. J., Corbett, H. J., … & Kendall, M. A. (2012). Nanopatch targeted delivery of both antigen and adjuvant to skin synergistically drives enhanced antibody responses. Journal of controlled release, 159(2), 215-221.

[4] Fernando, G. J., Hickling, J., Flores, C. M. J., Griffin, P., Anderson, C. D., Skinner, S. R., … & Rockman, S. (2018). Safety, tolerability, acceptability and immunogenicity of an influenza vaccine delivered to human skin by a novel high-density microprojection array patch (Nanopatch™). Vaccine, 36(26), 3779-3788.

[5] Larraneta, E., Lutton, R. E., Woolfson, A. D., & Donnelly, R. F. (2016). Microneedle arrays as transdermal and intradermal drug delivery systems: Materials science, manufacture and commercial development. Materials Science and Engineering: R: Reports, 104, 1-32.

[6] Naß, S. A. (2014). Limitations of the vaccine cold chain and the Nanopatch as an alternative approach.

[7] Tangermann, V. (2020, April 7). First Peer-Reviewed Coronavirus Vaccine Trial Shows Promising Results in Mice. https://www.sciencealert.com/scientists-in-pittsburgh-say-they-ve-already-developed-a-covid-19-vaccine-candidate

[8] Zehrung, D. (2017). Overview of emerging delivery technologies. WHO Product Development for Vaccines Advisory Committee (PDVAC) Consultation. http://www.who.int/immunization/research/meetings_workshops/PDVAC_2017_Delivery_Tech_Update_Zehrung_PATH.pdf

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Cooling Polymeric Paint

It’s a really warm Wisdom Wednesday!

Summer is definitely here, and the temperature is quickly rising. Thanks to various cooling technologies such as electric fans and air conditioners, we may feel a little more comfortable against the hot weather. However, most of these consume electricity and, as a result, add to the greenhouse gases that warm the environment even more.

In 2018, the total power consumed by the Philippines was reported to be at around 100,000 GWh. Twenty eight percent of the total power consumption is used by the residential sector. It is the largest sector that consumes electricity followed by the commercial then the industrial sectors. In a 2011 Household Energy Consumption Survey (HECS), it was reported that 66% of the households utilize electricity for space cooling. Among these, two-thirds utilize electric fans while the other one-third use an air conditioning unit.

With these, several energy-saving innovations have been proposed as an alternative cooling method. These utilize the passive daytime radiative cooling (PDRC) technology. PDRC is a simultaneous process wherein the sunlight is reflected and heat is radiated back to the atmosphere. The effectiveness of PDRC heavily relies on the material used. Firstly, the material should have a high reflectance at wavelengths of 0.3-2.5 μm (wavelength of sunlight). Secondly, the material should also be highly emissive at the long-wave infrared (LWIR) transmission window of the atmosphere. Since heat is trapped by the Earth’s atmosphere, the LWIR transmission window allows heat to travel back to outer space. This occurs at wavelengths of around 8-13 μm.  

Having satisfied both conditions would result in a net radiative heat loss. Moreover, as its name suggests, it does not require electricity, mechanical pumps, nor refrigerants to work due to its passive nature. One of the notable alternative cooling methods is the use of hierarchically porous poly(vinylidene fluoride-co-hexafluoropropene), [P(VdF-HFP)HP], coatings.

This coating can cool the sub-ambient temperature by approximately 6°C (43°F) under 890 watt per square meter solar intensity. It also demonstrates a cooling power of around 96 watt per square meter under 750 watt per square meter solar intensity.  Such performance equals or even exceeds those of the former PDRC models (e.g. photonic structures, polymer-dielectric composites on metal mirrors, cool-roof paints).

This material is initially prepared using three major components—a polymer, a solvent, and a nonsolvent. P(vinylidene fluoride-co-hexafluoropropene), or P(VdF-HFP), is used as the polymer, acetone as the solvent, and water as the nonsolvent. A film is applied on a substrate and is eventually air-dried. Due to the volatile nature of acetone, it immediately evaporates causing a phase-separation between water and the polymer. Next, the water evaporates which produces a network of air voids within the polymer.

The polymer, P(VdF-HFP), is optimal for PDRC due to its intrinsic electromagnetic properties. Its extinction coefficient is negligible at solar wavelengths. Thus, it has minimal absorbance and solar heating. Another property is having several extinction peaks in the LWIR transmission window wavelengths which implies efficient heat radiation at those wavelengths. On the other hand, its porous structures allow it to better backscatter light.

Having a solution-based coating is more convenient because it can be directly applied similar to a paint over existing surfaces such as wood, metal, or plastics. This is also an advantage over other designs that require pre-fabrication. Initially, the resulting solution has a white appearance; however, it can incorporate dyes in order to achieve a desired color.

The previously described technique for [P(VdF-HFP)HP] or the “phase inversion-based” technique may also be applied to other types of polymers such as polystyrene for temperatures greater than 200°C. Such attribute demonstrates great potential in fabricating specialized and generic PDRC coatings.

All in all, having a cost-efficient cooling polymeric paint would not only be eco-friendly, but also beneficial for those who wish to reduce their power consumption or for those who do not have ready access to electricity.

References:

[1] Mandal, Jyotirmoy, Yanke Fu, Adam C. Overvig, Mingxin Jia, Kerui Sun, Norman N. Shi, Hua Zhou, Xianghui Xiao, Nanfang Yu, and Yuan Yang. 2018. “Hierarchically porous polymer coatings for highly effective passive daytime radiative cooling.” Science 362 (6412): 315-319. doi: 10.1126/science.aat9513

[2] Columbia University School of Engineering and Applied Science. “Polymer coating cools down buildings.” ScienceDaily. http://www.sciencedaily.com/releases/2018/09/180927145555.htm

[3] Department of Energy. “2018 Power Statistics.” https://www.doe.gov.ph/sites/default/files/pdf/energy_statistics/01_2018_power_statistics_as_of_29_march_2019_summary.pdf?ckattempt=1

[4] Philippine Statistics Authority. 2013. “Electricity is the most common source of energy used by households.” https://psa.gov.ph/content/electricity-most-common-source-energy-used-households

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Hydroceramics

Whew, it’s a pretty hot Wisdom Wednesday!

Ever wonder when we’ll be able to invent a material that can lower temperature inside our homes without thinking much about the electricity consumption? Especially since we are in the tropics, summer has become one of the most anticipated seasons—well, as if there’s much of a choice—for people who enjoy beaches and going with all those Beat the Heat summer activities. But it is also a pain in one’s household pockets since we end up paying for higher electricity bills due to our more frequent use of cooling appliances to continue with our daily routines without getting all sweaty and irritated due to extreme heat.

This is where Hydroceramic comes into the picture, a glimpse to a possible material that could pave the way to a cooler future, in all aspects. Yes, they heard you! That’s why in 2013, a group of students from Institute for Advanced Architecture of Catalonia (IAAC) came up with a project that covers the future of intelligent constructions as they proposed a brick prototype that has thermal conditioning features. Exploring a smart material that is hydrogel, they made use of its properties as a polymer and infused it to one important part of a building or a house: its walls.

The composite material is composed of several layers, assembled like a brick or tile, namely: the ceramic layer, the absorbent fabric and the hydrogel. The ceramic layer is made up of clay which supports the whole material and holds the hydrogel within each pocket-like structure, then layered by the absorbent fabric that serves as another medium for the water and allows the expansion of the hydrogel. Lastly, a thinner ceramic layer with holes that gives way to an increased cooling surface area. And there you go, a sandwich-like material that passively responds to its environment.

Let’s have a closer look at our smart component, the hydrogel. They can be compared to a Jell-O with how they undergo phase transition when exposed to a change in temperature, but hydrogels are more specifically defined as hydrophilic crosslinked polymeric chains joined together by strong covalent bonds which promotes its thermosetting properties. The cross links prevent the polymeric chains from dissolving in water, therefore making hydrogels water insoluble. They are composed of up to 98% water, and can absorb water 500 times their weight. These properties of hydrogel made Hydroceramic’s mechanism function.

Here’s how it works: the hydrogel accumulates water and therefore expands turning it to its liquid state. When exposed to a higher temperature, it’ll undergo slow evaporation, losing water and going back to its original solid state. During the evaporation process, the ceramic layer absorbs the water from the hydrogel. They made use of the small porous properties of clay that help in the slow absorption of water, acting like how a sponge absorbs and maintains water, then its evaporation which causes a cooling of the surrounding.

The final prototype they have made could lower indoor surroundings by 5 to 6 °C. As it works passively, the hydrogel can hold water until there is a change in temperature that can trigger the material’s mechanism. Introducing Hydroceramics in a system as panels, the air conditioning’s temperature can be set higher than usual, such as setting it up 4°C higher, contributing to reducing the air conditioning’s overall electricity consumption by 28%. (This calculation was based on data conducted in Barcelona, Spain)

Also, it gives a promising future in terms of manufacturing since they explored the use of 3D printing in making some of the layers like the fabric channel. It can also be seen that this building alternative is cost-efficient as they have used materials that are inexpensive and common in the industry.

Looks like aside from a cool Wisdom Wednesday, we’ll have to watch out for very cool other days as well!

References:

[1] Hydroceramic. (n.d.). Retrieved April 4, 2020, from http://materiability.com/portfolio/hydroceramic/

[2] Hydroceramic. (n.d.). Retrieved from https://iaac.net/project/hydroceramic/

[3] Mora, V. (n.d.). Hydroceramic: intelligent walls. IAAC Research about thermosensitivity and autonomous thermal conditioning of surfaces. Retrieved from http://www.morethangreen.es/en/hydroceramic-intelligent-walls-iaac-research-about-thermosensitivity-and-autonomous-thermal-conditioning-of-surfaces/

[4] Rathi, A. (n.d.). Hydroceramic. Retrieved from https://issuu.com/akanksharathi/docs/final_booklet

[5] Paleos, G. A. (n.d.). What are Hydrogels? Pittsburgh Plastics Manufacturing Inc. Retrieved from http://www.pittsburghplastics.com/assets/files/What Are Hydrogels.pdf

[6] Lapidot, S. A., & Kost, J. (2001). In Encyclopedia of Materials: Science and Technology (2nd ed., pp. 3878–3882). Elsevier. doi: 10.1016/B0-08-043152-6/00688-4

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DDS: Drug Delivery Systems

Today’s not a day to fool around because it’s Wisdom Wednesday!

The emergence of infectious diseases has been a threat to the general public health and global security. These diseases have spurred the deadliest of pandemics like the Spanish flu of 1918 and the current struggle against HIV/AIDS. Now, the world is in the midst of the COVID-19 pandemic caused by the novel coronavirus, SARS-CoV-2.

The emergence and re-emergence of various diseases are linked to biological, social, and environmental factors. As such, researchers in the past few decades have focused on developing new antiviral drugs to curb these life-threatening infections. However, resistance to current drugs add to the unceasing scientific challenge of drug discovery and formulation. This led to the exploration of new avenues for attacking viral diseases and for improving success-of-treatment rates. 

Fortunately, our scientists—equipped with the latest medical technology—have increasingly become ingenious and creative. One of the current and flourishing research thrusts in the medical field would be the application of various DDSs in the treatment of various infectious diseases. 

Yes, folks, you read it right! DDSs might actually be useful!

A drug delivery system (DDS) is a formulation or a device that enables the introduction of a substance (usually a drug) to the body and increases its potency by controlling the rate, time, and site of release. It is important to note that a DDS is different from the drug itself. You see, the journey of a drug from outside your body to its target seems straightforward: the drug is first administered, then it gets released to the bloodstream allowing the pharmaceutical agent to eventually reach its intended site. However, several biological interferences may occur along the way that may hamper the drug’s performance. One can think of a DDS as a delivery vehicle that transports the drug safely and more precisely to its preferred destination. 

Say what now? A DDS, used to deliver drugs?! DROGA?! Well, yeah! And they’ve been around for so long that we’ve never stopped to think that even the most mundane of our medications are what we might consider as a “ka-DDS”.

One that we may be all too familiar with are orally administered drugs. The DDS associated with this comes as either a pill, a tablet, or a capsule—all of which can be generalized with the moniker “matrix tablets”. The drugs here are transported via macromolecule carriers, which have drug attachment sites, do not evoke unwanted body responses, and are biodegradable. However, bioavailability—the rate at which the unreacted substance reaches the specific site of action—has always been the issue of such drugs. They are exposed to a range of conditions during their movement in the gastrointestinal tract which, in turn, affects its reactivity and composition. Apart from the problem with bioavailability, conventional DDSs release the drug immediately with little or no control over the delivery rate.

To overcome these challenges, nanodelivery systems (nano-DDS) were introduced. These consist of nanoparticles, nanocapsules, vesicles, micelles, and inorganic nanomaterials, and are designed to deliver small molecular weight drugs. What are the advantages of downsizing a DDS, though? First, as a particle’s size decreases, a greater fraction of its atoms are located on the surface. Thus, the surface-area-to-volume ratio increases, making the particle more reactive. Nanocarriers also help control solubility and dissolution rates, protect sensitive drugs from deteriorating, increase bioavailability, and reduce side effects by improving the tissue drug tolerance. 

Because of its size, nano-DDSs provide the possibility of targeting specific body sites. Another advantage would be its capacity to be multi-functional through surface modification. Nano-DDSs can also be monitored using different imaging technologies. Thus, real-time observations and controls can be done to ensure the efficiency of these transport systems. Moreover, these drug carriers can be employed in ocular (eyes), transdermal (skin), dental (teeth), and intranasal (nose) delivery systems.

Nanoparticles have similar dimensions with viruses. One study investigated the physical interaction of silver nanoparticles with viruses and if this interaction can be utilized in developing a new antiviral strategy. It showed that nanoparticles with diameters ranging from 10 to 50 nm inhibited the infection caused by several viruses including HIV, HBV, and monkeypox. This study then concluded that nanoparticles act as an inhibitor of viral attachment and entry into the host’s cells. Hence, drugs in the nanometer scale can be our best bet against viruses.

Several methods are currently used for the preparation of DDSs. And no, it’s not through indoctrination nor blind idolatry! Such techniques include fluid extraction, electrospraying, layer-by-layer self-assembly, and micro-emulsion, among others. A wide range of materials can also be employed in fabricating DDSs. However, biopolymers hold the most promise. Biopolymers such as silk fibroins, collagen, gelatin, starch, chitosan, and cellulose can be used to ensure the biocompatibility and biodegradability of the DDS.

In conclusion, DDSs (both the conventional and nano-scaled approach) show immense promise in the treatment and eradication of infectious diseases. However, its potential must first be translated to actual clinical applications. To do this, we must invest in and perform extensive research! This entails unwavering support to scientists that move heaven and earth to make life easier for us. 

For now, we just have to wait for the day that these advanced DDSs will finally be useful in our society. #SolidDDS

References: 

[1] Artika, I Made, Ageng Wiyatno, and Chairin Nisa Maroef. “Pathogenic Viruses: Molecular Detection and Characterization.” Infection, Genetics and Evolution 81 (2020): 104215. https://doi.org/10.1016/j.meegid.2020.104215.

[2] Bruschi, Marcos Luciano. Strategies to Modify the Drug Release from Pharmaceutical Systems. Amsterdam: Elsevier/Woodhead Publishing, 2017.

[3] “Drug Delivery Systems.” National Institute of Biomedical Imaging and Bioengineering. U.S. Department of Health and Human Services. Accessed March 21, 2020. https://www.nibib.nih.gov/science-education/science-topics/drug-delivery-systems-getting-drugs-their-targets-controlled-manner.

[4] Fang, Xiaolin, Jiaojiao Cao, and Aizong Shen. “Advances in Anti-Breast Cancer Drugs and the Application of Nano-Drug Delivery Systems in Breast Cancer Therapy.” Journal of Drug Delivery Science and Technology 57 (2020): 101662. https://doi.org/10.1016/j.jddst.2020.101662.

[5] Jacob, Joby, Józef T. Haponiuk, Sabu Thomas, and Sreeraj Gopi. “Biopolymer Based Nanomaterials in Drug Delivery Systems: A Review.” Materials Today Chemistry 9 (2018): 43–55. https://doi.org/10.1016/j.mtchem.2018.05.002.

[6] Lembo, David, and Roberta Cavalli. “Nanoparticulate Delivery Systems for Antiviral Drugs.” Antiviral Chemistry and Chemotherapy 21, no. 2 (2010): 53–70. https://doi.org/10.3851/imp1684.

[7] Patra, Jayanta Kumar, Gitishree Das, Leonardo Fernandes Fraceto, Estefania Vangelie Ramos Campos, Maria Del Pilar Rodriguez-Torres, Laura Susana Acosta-Torres, Luis Armando Diaz-Torres, et al. “Nano Based Drug Delivery Systems: Recent Developments and Future Prospects.” Journal of Nanobiotechnology 16, no. 1 (2018). https://doi.org/10.1186/s12951-018-0392-8.

[8] Petrak, Karel. “The Structure and Properties of Materials Used in Advanced Drug Delivery Systems.” Bulletin of Materials Science 12, no. 1 (1989): 41–47. https://doi.org/10.1007/bf02744593.

[9] Thassu, Deepak, Yashwant Pathak, and Michel Deleers. “Nanoparticulate Drug-Delivery Systems: An Overview.” Nanoparticulate Drug Delivery Systems, 2007, 1–31. https://doi.org/10.1201/9781420008449-1.

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Soap vs. Alcohol-based Sanitizers, and Coronavirus

It’s Wisdom Wednesday!

Viral diseases pose a serious problem to our public health as they continue to emerge and develop throughout the world. Several epidemics such as the Middle East respiratory syndrome coronavirus (MERS-CoV), severe acute respiratory syndrome coronavirus (SARS-CoV), and H1N1 influenza have been recorded in the last two decades. The most recent viral disease that has been detected is due to a novel coronavirus in Wuhan, China last December 2019. The virus itself is called SARs-CoV-2, while the disease it brings is officially dubbed as the coronavirus disease 2019 (COVID-19). 

Presently, the disease has now spread in over 100 locations globally with many countries under lockdown to combat its spread. With that, the World Health Organization (WHO) has declared COVID-19 a pandemic. 

The coronavirus is a large family of viruses that causes illness such as respiratory infections to humans and animals. Transmission of this virus is usually between a human and an animal, but it can develop into a person-to-person transmitted disease. 

Most viruses have three essential components: nucleic acid (DNA or RNA), proteins, and lipids. COVID-19 is a self-assembled RNA enveloped in glycoproteins, a lipid membrane, and a crown of protein spikes, hence the moniker ‘coronavirus’. The RNA, proteins, and lipids are held together by non-covalent interactions that stick strongly on surfaces. This makes it difficult to remove the virus by washing infected surfaces with water only. Our skin is actually an ideal substrate for viruses because it’s organic and has proteins and fatty acids where the virus can interact and thrive. 

Common symptoms of COVID-19 include dry cough, fever, shortness of breath, and tiredness. It takes around 2-14 days from exposure before symptoms manifest. Although the disease is mild especially for young adults and children, severe complications such as pneumonia and multi-organ failure can develop for older people and persons with pre-existing medical conditions such as high blood pressure, heart disease, lung ailments, cancer or diabetes.

To protect yourself from the virus, WHO advises us to regularly wash your hands with soap or with alcohol-based sanitizers.

Soaps are surface-active agents, also known as surfactants, made by hydrolysis of oils and fats such as stearic, palmitic, and oleic acid with sodium or potassium salts (NaOH and KOH). A soap molecule is made of a nonpolar hydrophobic tail (hydrocarbon) and a polar hydrophilic head (-COO^–Na⁺). The head is water-soluble while the tail is soluble in oil/grease. 

The way soap cleans many surfaces and our bodies is because of its structure. In the presence of water, the nonpolar tail of the soap molecule attaches itself and dissolves the oil/grease that contains dirt and the polar head remains in the water layer surrounding the oil/grease. The soap molecules arrange themselves around the surface of dirt particles forming micelles. These micelles do not coalesce with each other due to the accumulated negative charge at the surface from the polar head of the soap molecule (-COO^–). These micelles are then washed away with water, thus removing dirt from a surface.

Of course, soaps can also be used to remove bacteria and viruses which have lipid (fatty) membranes. The soap can disrupt and break the chemical bonds of those membranes and form micelles around the fragments of the virus or bacterium. In the case of COVID-19, soap is very effective in removing SARs-CoV-2 from our skin and other surfaces. Soap not only breaks the structure of the self-assembled virus but also loosens the strong attachment of the virus on our skin. The friction of washing with soap and water also works to reduce the dirt and other microbes on our skin and other infected surfaces.

Aside from its superior cleaning, antibacterial, and antiviral ability, soap is relatively cheap. It’s abundant and easily accessible; You can find it in supermarkets, drugstores, convenience stores, and even ‘sari-sari’ stores. However, soap is dependent on water to form the micelles and remove dirt and viruses, and not everyone has access to water. Another disadvantage of soap is that it is much less efficient with “hard water” which contains Ca²⁺ and Mg²⁺ ions. These ions form insoluble salts with soap (calcium and magnesium soap) which prevents the formation of micelles and are just eventually washed away. 

Luckily, there’s another way to clean our hands and protect ourselves from the virus which is alcohol-based sanitizers. Alcohol is an organic compound containing one hydroxyl group (-OH) connected to a saturated carbon atom. The most common alcohols used in hand sanitizers and disinfectants are ethyl and isopropyl alcohols.  

Ethyl alcohol (aka ethanol) is a simple, two-carbon alcohol with a hydroxyl group at its end. It is hydrophilic due to the terminal hydroxyl group but also has some nonpolar characteristics due to the hydrophobic carbon chain. On the other hand, isopropyl alcohol (aka isopropanol) is a three-carbon alcohol with a hydroxyl group bonded at the middle carbon atom. 

Similar to soaps, the hydrophobic carbon chains in alcohols allow them to dissolve nonpolar compounds like oils; however, unlike soaps, they do not form micelles. Alcohols can denature proteins and dissolve lipids present in bacteria, fungi, and viruses. Moreover, alcohol-based hand sanitizers can be used as is, so there is no need for water! Unless, of course, it’s for the initial dilution. 

Speaking of dilution, alcohol-based sanitizers are only effective above 60% concentration. Otherwise, not all the viruses and bacteria will be killed. Concentrations above 70% are also not advised due to the rapid evaporation of the alcohol and the proteins in the virus are not denatured easily in the absence of water. Another problem of alcohol-based sanitizers is that people may not be using enough volume of the sanitizer or they wipe it off before it has dried, reducing the effectiveness of the alcohol. These sanitizers are also not effective against heavily soiled or greasy hands. Moreover, alcohol-based sanitizers are much more expensive compared to soap, and their current supply is limited. 

Although this pandemic is certainly scary, we can protect ourselves from it by just washing our hands and other affected surfaces with soap and water. In the case soap and water is unavailable, alcohol-based sanitizers are just as effective. Just remember to fully rub your hands with your choice of disinfectant for at least 20 seconds. Other preventive measures should also be taken such as distancing ourselves from people who are infected, staying at home when we are sick, wearing masks, practicing proper respiratory hygiene (covering our mouths when we cough and sneeze), and keeping up with the latest news regarding COVID-19.  

Stay safe. Stay informed. Wash your hands!

References 

[1] Charbonneau, D. L., J. M. Ponte, and B. A. Kochanowksi. “A Method of Assessing the Efficacy of Hand Sanitizers: Use of Real Soil Encountered in the Food Service Industry.” Journal of Food Protection 63, no. 4 (April 2000), 495-501. doi:10.4315/0362-028x-63.4.495.

[2] Gold, Nina A., and Usha Avva. Alcohol Sanitizer. Treasure Island (FL): StatPearls Publishing, 2020. https://www.ncbi.nlm.nih.gov/books/NBK513254/.

[3] Hui, David S., Esam I Azhar, Tariq A. Madani, Francine Ntoumi, Richard Kock, Osman Dar, Giuseppe Ippolito, et al. “The continuing 2019-nCoV epidemic threat of novel coronaviruses to global health — The latest 2019 novel coronavirus outbreak in Wuhan, China.” International Journal of Infectious Diseases 91 (2020), 264-266. doi:10.1016/j.ijid.2020.01.009.

[4] Jain, Mahendra. “Oils, Fats, Soaps, Detergents, and Waxes.” Competition Science Vision, November 2007.

[5] Kampf, G. “Efficacy of ethanol against viruses in hand disinfection.” Journal of Hospital Infection 98, no. 4 (2018), 331-338. doi:10.1016/j.jhin.2017.08.025.

[6] Lewis, Ricky. “COVID-19 Vaccine Will Close in on the Spikes.” PLOS Blogs Network | Diverse Perspectives on Science and Medicine. Last modified February 20, 2020. https://blogs.plos.org/dnascience/2020/02/20/covid-19-vaccine-will-close-in-on-the-spikes/.

[7] Mohammed, Manal. “Coronavirus: Not All Hand Sanitisers Work Against It – Here’s What You Should Use.” The Conversation. Last modified March 13, 2020. https://theconversation.com/coronavirus-not-all-hand-sanitisers-work-against-it-heres-what-you-should-use-133277.

[8] Pommerville, Jeffrey C. “A Variety of Chemical Methods can Control Microbial Growth.” In Fundamentals of Microbiology. Burlington: Jones & Bartlett Publishers, 2014.

[9] “Q&A on Coronaviruses (COVID-19).” WHO | World Health Organization. Last modified March 9, 2020. https://www.who.int/news-room/q-a-detail/q-a-coronaviruses.

[10] Stebbins, Samuel, Derek A. Cummings, James H. Stark, Chuck Vukotich, Kiren Mitruka, William Thompson, Charles Rinaldo, et al. “Reduction in the Incidence of Influenza A But Not Influenza B Associated With Use of Hand Sanitizer and Cough Hygiene in Schools.” The Pediatric Infectious Disease Journal 30, no. 11 (November 2011), 921-926. doi:10.1097/inf.0b013e3182218656.

[11] Thordarson, Palli. “Deadly Viruses Are No Match for Plain, Old Soap — Here’s the Science Behind It.” MarketWatch. Last modified March 14, 2020. https://www.marketwatch.com/story/deadly-viruses-are-no-match-for-plain-old-soap-heres-the-science-behind-it-2020-03-08

[12] Zhu, Na, Dingyu Zhang, Wenling Wang, and Xingwang Li. “A Novel Coronavirus from Patients with Pneumonia in China, 2019.” The New England Journal of Medicine, no. 382 (February 2020), 727-733. doi:10.1056/NEJMoa2001017.

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