Biopolymer Coating Imparts Sustainable Self-Disinfecting and Antimicrobial Properties to Fabric: Translated to Protective Gears for the Pandemic and Beyond

Utilizing Rapid Hydrogen Peroxide Generation from 6-Hydroxycatechol to Design Moisture-Activated, Self-Disinfecting Coating

A coating that can be activated by moisture found in respiratory droplets could be a convenient and effective way to control the spread of airborne pathogens and reduce fomite transmission. Here, the ability of a novel 6-hydroxycatechol-containing polymer to function as a self-disinfecting coating on the surface of polypropylene (PP) fabric was explored. Catechol is the main adhesive molecule found in mussel adhesive proteins. Molecular oxygen found in an aqueous solution can oxidize catechol and generate a known disinfectant, hydrogen peroxide (H2O2), as a byproduct. However, given the limited amount of moisture found in respiratory droplets, there is a need to enhance the rate of catechol autoxidation to generate antipathogenic levels of H2O2. 6-Hydroxycatechol contains an electron donating hydroxyl group on the 6-position of the benzene ring, which makes catechol more susceptible to autoxidation. 6-Hydroxycatechol-coated PP generated over 3000 μM of H2O2 within 1 h when hydrated with a small amount of aqueous solution (100 μL of PBS). The generated H2O2 was three orders of magnitude higher when compared to the amount generated by unmodified catechol. 6-Hydroxycatechol-containing coating demonstrated a more effective antimicrobial effect against both Gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) bacteria when compared to unmodified catechol. Similarly, the self-disinfecting coating reduced the infectivity of both bovine viral diarrhea virus and human coronavirus 229E by as much as a 2.5 log reduction value (a 99.7% reduction in viral load). Coatings containing unmodified catechol did not generate sufficient H2O2 to demonstrate significant virucidal effects. 6-Hydroxycatechol-containing coating can potentially function as a self-disinfecting coating that can be activated by the moisture present in respiratory droplets to generate H2O2 for disinfecting a broad range of pathogens.

Antibiofilm Activity of Eugenol-Loaded Chitosan Coatings against Common Medical-Device-Contaminating Bacteria

The formation of pathogenic biofilms on medical devices is a major public health concern accounting for over 65% of healthcare-associated infections and causing high infection morbidity, mortality, and a great burden to patients and the healthcare system due to its resistance to treatment. In this study, we developed a chitosan-based antimicrobial coating with embedded mesoporous silica nanoparticles (MSNs) to load and deliver eugenol, an essential oil component, to inhibit the biofilm formation of common bacteria in medical-device-related infections. The eugenol-loaded MSNs were dispersed in a chitosan solution, which was then cross-linked with glutaraldehyde and drop-casted to obtain coatings. The MSNs and coatings were characterized by dynamic light scattering, Brunauer-Emmett-Teller analysis, attenuated-total-reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, 3D optical profilometry, and scanning electron microscopy. The release behavior of eugenol-loaded MSNs and coatings and the antibiofilm and antimicrobial activity of the coatings against adherent Staphylococcus aureus, methicillin-resistant S. aureus, and Pseudomonas aeruginosa were investigated. Eugenol was released from the MSNs and coatings in aqueous conditions in a controlled manner with an initial low release, followed by a peak release, a decrease, and a plateau. While the chitosan coatings alone or with unloaded MSNs demonstrated limited antimicrobial effects and still supported biofilm formation after 24 h, the coating containing eugenol not only reduced biofilm formation but also killed the majority of the attached bacteria. It also showed biocompatibility in indirect contact with NIH/3T3 fibroblasts and a high percentage of live cells in direct contact. However, further investigations into cell proliferation in direct contact are recommended. The findings indicated that the chitosan-based coating with eugenol-loaded MSNs could be developed into an effective strategy to inhibit biofilm formation on medical devices.

Guarding skin under PPE: Mechanistic insights and technological innovations

In the presence of diseases transmitted through respiratory droplets and direct contact, healthcare workers (HCWs) necessitate the use of personal protective equipment (PPE). For optimal safety, PPE should securely conform to the skin during extended wear. However, conventional PPE often lacks adequate air permeability and hygroscopicity, trapping heat and moisture emitted by the body within the enclosure. Such a hot and humid internal environment can induce skin damage, such as erythema, rash, pruritus, and itching among others, leading to microbial growth on the skin surface, the production of inflammatory mediators at the wound site and an increased risk of infection. This review strives to comprehensively elucidate the fundamental mechanisms triggering adverse skin reactions and their resultant manifestations. Furthermore, we explore recent advancements aimed at inhibiting these mechanisms to effectively mitigate the occurrence of skin lesions.