Cationic Conjugated Microporous Polymers Coating for Dual-Modal Antimicrobial Inactivation with Self-Sterilization and Reusability Functions

COVID-19 pandemic outbreak poses a great threat to human health. Face masks have been considered as important personal protective equipment to prevent the COVID-19 transmission. However, pathogens can survive up to several days on the fabrics of commercial masks, which increases the risk of direct/indirect microbial transmission. Herein, new cationic conjugated microporous polymers (CCMPs)-based coating is developed, which possesses extended π-conjugated skeletons and massive quaternary ammonium salt (QAS) groups, exhibiting dual-modal antimicrobial inactivation, including sunlight-driven photodynamic sterilization through the generation of reactive oxygen species and contact sterilization through QAS groups. As a result, the CCMPs coatings can rapidly and efficiently eradicate 99% of model microbes, such as Escherichia coli and Staphylococcus aureus under solar illumination, and also ensure the great antimicrobial effect in the absence of light. More importantly, the CCMPs coatings exhibit excellent durability, reusability as well as antimicrobial stability in humid environment. Contributing to the outstanding processability and formability, CCMPs can be in situ synthesized and coated over fibers through a simple spray procedure. Taken together, the design provides a promising strategy for developing reusable and self-sterilizing antimicrobial fabrics, particularly for the application of face masks to tackle infectious pathogen and viruses in daily protection and medical applications. © 2023 Wiley-VCH GmbH.

Eco-friendly chitosan@silver/plant fiber membranes for masks with thermal comfortability and self-sterilization.

The surgical masks have been essential consumables for public in the COVID-19 pandemic. However, long-time wearing masks will make wearers feel uncomfortable and massive discarded non-biodegradable masks lead to a heavy burden on our environment. In this paper, we adopt degradable chitosan@silver (CS@Ag) core-shell fibers and plant fibers to prepare an eco-friendly mask with excellent thermal comfort, self-sterilization, and antiviral effects. The thermal network of CS@Ag core-shell fibers highly improves the in-plane thermal conductivity of masks, which is 4.45 times higher than that of commercial masks. Because of the electrical conductivity of Ag, the fabricated mask can be electrically heated to warm the wearer in a cold environment and disinfect COVID-19 facilely at room temperature. Meanwhile, the in-situ reduced silver nanoparticles (AgNPs) endow the mask with superior antibacterial properties. Therefore, this mask shows a great potential to address the urgent need for a thermally comfortable, antibacterial, antiviral, and eco-friendly mask. Supplementary Information: The online version contains supplementary material available at 10.1007/s10570-022-04582-x.

Violacein-embedded nanofiber filters with antiviral and antibacterial activities.

Most respiratory masks are made of fabrics, which only capture the infectious virus carriers into the matrix. However, these contagious viruses stay active for a long duration (∼7 days) within the fabric matrix possibly inducing post-contact transmissions. Moreover, conventional masks are vulnerable to bacterial growth with prolonged exposure to exhaled breaths. Herein, we combined violacein, a naturally-occurring antimicrobial agent, with porous nanofiber membranes to develop a series of functional filters that autonomously sterilizes viruses and bacteria. The violacein-embedded membrane inactivates viruses within 4 h (99.532 % reduction for influenza and 99.999 % for human coronavirus) and bacteria within 2 h (75.5 % reduction). Besides, its nanofiber structure physically filters out the nanoscale (<0.8 µm) and micron-scale (0.8 µm - 3 µm) particulates, providing high filtration efficiencies (99.7 % and 100 % for PM 1.0 and PM 10, respectively) with long-term stability (for 25 days). In addition, violacein provides additional UV-resistant property, which protects the skin from sunlight. The violacein-embedded membrane not only proved the sterile efficacy of microbe extracted pigments for biomedical products but also provided insights to advance the personal protective equipment (PPE) to fight against contagious pathogens.

Multi-Scale Nanoarchitectured Fibrous Networks for High-Performance, Self-Sterilization, and Recyclable Face Masks.

Airborne particulate matter (PM) pollutants, especially with nanoscale size, have caused serious public health issues. The global demand for high-performance and recyclable face masks is increasing dramatically, especially during the COVID-19 pandemic. However, present masks suffer from low-efficiency interception of PM0.3 /pathogen, limited air permeability, and incapacity to reuse and recycle. Here, multi-scale nanoarchitectured nanofiber/carbon nanotube (NF/CNT) networks are constructed by a needleless-electrospinning/spraying-netting strategy, enabling well-dispersed CNT networks (diameter ≈ 25 nm) welded on charged nanofibrous scaffolds (diameter > 100 nm) layer by layer. The optimized NF/CNT networks possess a fluffy structure with narrow-distribution small pores (size ≈ 400 nm), "free molecular flow" behavior, and electrostatic adsorption property, thereby exhibiting high filtration efficiency (>99.994% PM0.3 removal) and low resistance (<0.05% atmosphere pressure). Furthermore, they demonstrate reliable and ultra-fast photothermal-driven self-sterilization (>99.986% in 5 min) under 1 sun and electrothermal-driven self-sterilization (>99.9999% in 2 min) in sunless scenes owing to their unique nanoarchitecture. Most importantly, the abandoned NF/CNT filters can be fully recycled as high-performance solar vapor generators to desalinate seawater (3.56 L m-2 d-1 ). This work offers a fascinating solution to reduce disease transmission, resource consumption, and environmental burdens.

Functionalized Masks: Powerful Materials against COVID-19 and Future Pandemics.

The outbreak of COVID-19 revealed the vulnerability of commercially available face masks. Without having antibacterial/antiviral activities, the current masks act only as filtering materials of the aerosols containing microorganisms. Meanwhile, in surgical masks, the viral and bacterial filtration highly depends on the electrostatic charges of masks. These electrostatic charges disappear after 8 h, which leads to a significant decline in filtration efficiency. Therefore, to enhance the masks' protection performance, fabrication of innovative masks with more advanced functions is in urgent demand. This review summarizes the various functionalizing agents which can endow four important functions in the masks including i) boosting the antimicrobial and self-disinfectant characteristics via incorporating metal nanoparticles or photosensitizers, ii) increasing the self-cleaning by inserting superhydrophobic materials such as graphenes and alkyl silanes, iii) creating photo/electrothermal properties by forming graphene and metal thin films within the masks, and iv) incorporating triboelectric nanogenerators among the friction layers of masks to stabilize the electrostatic charges and facilitating the recharging of masks. The strategies for creating these properties toward the functionalized masks are discussed in detail. The effectiveness and limitation of each method in generating the desired properties are well-explained along with addressing the prospects for the future development of masks.

Reusable Self-Sterilization Masks Based on Electrothermal Graphene Filters.

Surgical mask is recommended by the World Health Organization for personal protection against disease transmission. However, most of the surgical masks on the market are disposable that cannot be self-sterilized for reuse. Thus, when confronting the global public health crisis, a severe shortage of mask resource is inevitable. In this paper, a novel low-cost electrothermal mask with excellent self-sterilization performance and portability is reported to overcome this shortage. First, a flexible, ventilated, and conductive cloth tape is patterned and adhered to the surface of a filter layer made of melt-blown nonwoven fabrics (MNF), which functions as interdigital electrodes. Then, a graphene layer with premier electric and thermal conductivity is coated onto the MNF. Operating under a low voltage of 3 V, the graphene-modified MNF (mod-MNF) can quickly generate large amounts of heat to achieve a high temperature above 80 °C, which can kill the majority of known viruses attached to the filter layer and the mask surface. Finally, the optimized graphene-modified masks based on the mod-MNF filter retain a relatively high particulate matter (PM) removal efficiency and a low-pressure drop. Moreover, the electrothermal masks can maintain almost the same PM removal efficiency over 10 times of electrifying, suggesting its outstanding reusability.