In the early days of the pandemic, reports circulated that surfaces were a significant source of transmission for COVID-19. As such, surfaces of all manner, shape and size were called into question — everything from door handles, countertops, tabletops, electronic devices, even playground equipment surfaces and ATM touchscreens.

Several months later and the emphasis on transmission has shifted slightly from surfaces to person-to-person contact, transmitted via aerosol droplets from coughing, laughing, talking, sneezing and yelling. Despite a dwindling emphasis on surface transmissions of COVID-19, where the virus can reportedly live for anywhere from two hours to 10 days, surfaces are still a threat, albeit a less significant one.

As such, countless surface solutions for potentially limiting the risk of surface transmission of the virus have emerged in recent months and continue to do so.

Following are just some of the surface solutions to emerge from the pandemic so far.

Killer coating

A chemical engineer from Virginia Polytechnic Institute and State University (Virginia Tech) has created a coating that can reportedly inactivate COVID-19 in under one hour. The film is a combination of cuprous oxide (Cu2O) particles bound with polyurethane, which reportedly inactivated 99.9% of the SARS-CoV-2 virus when the coating was applied to glass and stainless-steel surfaces in the lab.

The coating, which can be painted on objects such as doorknobs, light switches and shopping cart handles also proved durable during testing, inactivating the virus even after objects coated with the film were submerged in water.

Oil and gas surfaces

To prevent the spread of COVID-19 on offshore oil and gas platforms, marine engineering company TSG Marine has created a molecular film for high contamination risk surfaces in the energy sector.

The film, called Zoono, binds to surfaces and inactivates molds, bacteria and viruses, keeping treated surfaces safe for a reported 30 days.

The film is applied via fog or spray and it contains positively charged microscopic spines that simultaneously attract and then penetrate pathogens, ultimately destroying them.

Liquid repellent film

Source: PNNLSource: PNNL

Materials scientists from the Pacific Northwest National Laboratory (PNNL) in Washington state have developed a liquid repellent coating for surgical gloves and other personal protective equipment (PPE) to help prevent the spread of COVID-19.

The coating, called ElastiDry, is a non-toxic substance containing hydrophobic silica fibers that wick away infectious liquids. Making the substance ideal for PPE is that it still works when stretched, according to its developers.

The PNNL team believes that the coating could be added to other medical products including hospital gowns, aprons, medical devices, hospital bedding, walls and surfaces, pipettes, beakers and tubing.

Multiple polymer coatings

Researchers from Hong Kong University of Science and Technology have created an antimicrobial polymer coating that destroys bacteria, viruses and spores.

Pipes treated with MAP-1 on the left and untreated one on the right. Source: The Hong Kong University of Science and TechnologyPipes treated with MAP-1 on the left and untreated one on the right. Source: The Hong Kong University of Science and Technology

The multilevel antimicrobial polymer (MAP-1) coating is a mixture of several antimicrobial polymers. When heat or moisture is applied to the coating, the polymers release disinfectants that inactivate bacteria, spores and viruses that cause mumps, measles, rubella and even COVID-19.

The team intends to explore the possibility of adding the coating to water and sewage pipes to prevent bacteria that corrode pipes. Likewise, the team intends to incorporate the coating into nanofibers used in surgical masks, curtains, hospital sheets and other linens.

Metal ion coatings

A team from Ben-Gurion University of the Negev (BGU) in Israel is attempting to develop anti-viral nanoparticle coatings that could potentially prevent surface transmissions of COVID-19.

The nanocoating is composed of nanoparticles of metal ions and polymers with anti-viral and anti-microbial properties. The nanoparticles reportedly offer a slow release of the metal ions and their anti-viral properties onto treated surfaces. The controlled release of the metal ions means that the nanocoating can be effective for extended periods — for weeks and even months at a time.This scanning electron microscope image shows SARS-CoV-2 (yellow) — also known as 2019-nCoV, the virus that causes COVID-19 — isolated from a patient, emerging from the surface of cells (blue/pink) cultured in the lab. Source: NIAID-RMLThis scanning electron microscope image shows SARS-CoV-2 (yellow) — also known as 2019-nCoV, the virus that causes COVID-19 — isolated from a patient, emerging from the surface of cells (blue/pink) cultured in the lab. Source: NIAID-RML

The film can either be painted or sprayed onto surfaces in high risk settings such as in hospitals, healthcare facilities, schools, airports and mass transportation hubs.

Light-activated film

Researchers from the University College London have created a light-activated antimicrobial coating that kills bacteria under low intensity, ambient light conditions.

During testing, the research team used the coating to destroy Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), some of the bacteria at the source of healthcare associated infections (HCAIs). In the lab, the bacteria were introduced to the film, which is composed of minute clusters of chemically modified gold encased in a polymer containing a dye called crystal violet that possesses antifungal and antibacterial properties.

When exposed to low intensity ambient light in the 300 lux range — similar to lighting encountered in a hospital ward or waiting room, for instance — the dye produced reactive oxygen species that inactivated the bacteria by attacking their protective membranes and DNA. According to researchers, this capability in the dye is enhanced with the addition of metals including zinc oxide, silver and, in this instance, gold.

Setting this coating apart from similar coatings is that other recently developed antimicrobial coatings require ultraviolet (UV) light to kill bacteria, which is dangerous for humans, whereas low intensity, ambient light is not.

Researchers believe the coating could potentially be used in a host of applications including on smartphone screens, keyboards and inside catheter and breathing tubes, all of which are potentially high risk zones for spreading HCAIs.

Check back with Engineering360 for any technological developments to emerge from the COVID-19 pandemic.

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