Cotton fabrics with durable and reusable daylight-induced antibacterial/antiviral functions were developed by using a novel fabrication process, which employs strong electrostatic interaction between cationic cotton fibers and anionic photosensitizers. The cationic cotton contains polycationic short chains produced by a self-propagation of 2-diehtylaminoehtyl chloride (DEAE-Cl) on the surface of cotton fibers. Then, the fabric (i.e., polyDEAE@cotton) can be readily functionalized with anionic photosensitizers like rose Bengal and sodium 2-anthraquinone sulfate to produce biocidal reactive oxygen species (ROS) under light exposure and consequently provide the photo-induced biocidal functions. The biocidal properties of the photo-induced fabrics (PIFs) were demonstrated by ROS production measurements, bactericidal performance against bacteria (e.g., E coli and L. innocua), and antiviral results against T7 bacteriophage. The PIFs achieved 99.9999% (6 log) reductions against bacteria and the bacteriophage within 60 min of daylight exposure. Moreover, the PIFs showcase excellent washability and photostability, making them ideal materials for reusable face masks and protective suits with improved biological protections compared with traditional PPE. This work demonstrated that the cationized cotton could serve as a platform for different functionalization applications, and the resulting fiber materials could inspire the development of reusable and sustainable PPE with significant bioprotective properties to fight the COVID-19 pandemic as well as the spread of other contagious diseases.

Photoactivities of four natural or naturalderivatized vitamin K (VK) species were investigated by using a combination of theoretical computational modeling, prediction, and specially designed experimental tests. The results revealed that these VK compounds are photoactive in the generation of reactive oxygen species of hydroxyl radicals and singlet oxygen under daylight, UVA, and UVB irradiations. Two possible photoreaction paths exist in an environment of good or poor hydrogen donors. Vitamin K 3 (VK 3 ), as an aromatic naphthoquinone compound, was predicted and demonstrated as the most effective photoactive agent under a broad range of UV−vis wavelengths and in production of both hydroxyl radicals and singlet oxygen. VK 1 and VK 2 are less active than VK 3 due to the existence of double bonds in their side chains of naphthoquinone. VK 4 is different in photoactivity due to the loss of an aromatic ketone structure. As an example, VK 3 was tested against Gram-negative Escherichia coli and Gram-positive Listeria innocua under daylight irradiation and exhibited complete kill of Escherichia coli (six log reduction in 60 min of daylight exposure) and Listeria innocua (five log reduction in 90 min of daylight exposure). In addition, VK 3 retained its high bactericidal efficacy toward both Escherichia coli and Listeria innocua after seven times of repeated daylight exposures, indicating excellent reusability as a green biocide. This work provides insight into the development of green and sustainable photoinduced antimicrobial materials for biomedical and food safety applications.

During the development of antibacterial and antiviral materials for personal protective equipment (PPE), daylight active functional polymeric materials containing vitamin K compounds (VKs) and impacts of polymer structures to the functions were investigated. As examples, hydrophobic polyacrylonitrile (PAN) and hydrophilic poly­(vinyl alcohol-co-ethylene) (PVA-co-PE) polymers were directly blended with three VK compounds and electrospun into VK-containing nanofibrous membranes (VNFMs). The prepared VNFMs exhibited robust photoactivity in generating reactive oxygen species (ROS) under both daylight (D65, 300–800 nm) and ultraviolet A (UVA, 365 nm) irradiation, resulting in high antimicrobial and antiviral efficiency (>99.9%) within a short exposure time (<90 min). Interestingly, the PVA-co-PE/VK3 VNFM showed higher ROS production rates and better biocidal functions than those of the PAN/VK3 VNFM under the same photoirradiation conditions, indicating that PVA-co-PE is a better matrix polymer material for these functions. Moreover, the prepared PVA-co-PE/VK3 VNFM maintains its powerful microbicidal function even after five times of repeated exposures to bacteria and viruses, showing the stability and reusability of the antimicrobial materials. The fabrication of photoinduced antimicrobial VNFMs may provide new insights into the development of non-toxic and reusable photoinduced antimicrobial materials that could be applied in personal protective equipment with improved biological protections.

Menadione sodium bisulfite (MSB), also known as water-soluble vitamin K3 widely used as an animal food additive due to its low toxicity and low cost, is for the first time proven to be photoactive and antibacterial under various photoirradiation sources, evidenced by a computational modeling method and well-designed experiments. MSB demonstrates its robust photoactivity and application potential under ultraviolet A (UVA, 315–400 nm) irradiation. The results reveal that MSB could effectively generate reactive oxygen species (ROS) under UVA irradiation due to the formation of its oxidative triplet excited state. The photoinduced antibacterial tests also demonstrate the nonselective bacterial inactivation functions of MSB under proper photoirradiation. MSB was challenged against Gram-negative Escherichia coli (E. coli) and Gram-positive Listeria innocua (L. innocua) under UVA irradiation and exhibited excellent antibacterial performance (99.999% bacterial inactivation in 30 min of UVA exposure) in PBS. The antibacterial performance of MSB does not decay after five times of repeated exposures to bacteria and UVA irradiation, indicating the photostability and durability of MSB as a photoinduced antibacterial agent. More interestingly, solvents played a significant role in photoinduced antibacterial properties but not in the generation of ROS of MSB, indicating that the solvents may serve as contact media between MSB and bacteria cells. Intimate contact of MSB and microorganisms is thought of as a determinant in the bacterial inactivation by ROS or triplet excited states due to their relatively short lifetime and limited diffusion and function radius.

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