Abstract
Toward the objective of developing platform technologies for anti-infective materials based upon photodynamic inactivation, we employed electrospinning to prepare a non-woven textile comprised of polyacrylonitrile nanofibers embedded with a porphyrin-based cationic photosensitizer; termed PAN-Por(+). Photosensitizer loading was determined to be 34.8 nmol/mg material; with thermostability to 300 °C. Antibacterial efficacy was evaluated against four bacteria belonging to the ESKAPE family of pathogens (Staphylococcus aureus; vancomycin-resistant Enterococcus faecium; Acinetobacter baumannii; and Klebsiella pneumonia), as well as Escherichia coli. Our results demonstrated broad photodynamic inactivation of all bacterial strains studied upon illumination (30 min; 65 ± 5 mW/cm2; 400–700 nm) by a minimum of 99.9996+% (5.8 log units) regardless of taxonomic classification. PAN-Por(+) also inactivated human adenovirus-5 (~99.8% reduction in PFU/mL) and vesicular stomatitis virus (>7 log units reduction in PFU/mL). When compared to cellulose-based materials employing this same photosensitizer; the higher levels of photodynamic inactivation achieved here with PAN-Por(+) are likely due to the combined effects of higher photosensitizer loading and a greater surface area imparted by the use of nanofibers. These results demonstrate the potential of photosensitizer-embedded polyacrylonitrile nanofibers to serve as scalable scaffolds for anti-infective or self-sterilizing materials against both bacteria and viruses when employing a photodynamic inactivation mode of action.
Highlights
According to the center for disease control’s (CDC’s) Healthcare-Associated Infections (HAI)Prevalence Survey, there were an estimated 722,000 HAIs in U.S acute care hospitals in 2011, equivalent to ~1 out of every 25 inpatients having at least one health care–associated infection on any given day [1].Approximately 75,000 deaths were attributed to these infections, or about 10% of the total HAIs
Though typically not a concern for healthy individuals, a second factor that contributes to HAIs is drug resistance, and five classes of antibiotic-resistant pathogens in particular have emerged as major public health threats: vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant mycobacteria, Gram-negative bacteria, and fungi [8]
Our results demonstrated that PAN-Por(+) possesses broad antibacterial efficacy, with equivalent levels of inactivation being observed regardless of the bacterial strain tested, and at levels that exceeded Por(+) -paper or Por(+) -CNCs, the two cellulose-based materials employing the same photosensitizer via a covalent linkage to the polymer scaffold
Summary
According to the center for disease control’s (CDC’s) Healthcare-Associated Infections (HAI). Advantages of materials-based aPDI include (i) employing singlet oxygen as the biocidal agent (which, given its short lifetime and decay to harmless oxygen as an end product [29] can be considered environmentally benign); (ii) multiple routes to PS incorporation, including the attachment of the PS through electrostatic interactions [30], encapsulation within a polymeric matrix [30,31,32,33,34,35,36], or direct attachment via a covalent bond (prevents leaching into the environment) [37,38,39,40,41,42,43,44]; (iii) the ability of the PS to potentially function in the absence of direct contact with the pathogen due to the diffusibility of singlet oxygen [40,45]; and (iv) of great importance with respect to nosocomial infections is that singlet oxygen or other photo-generated reactive oxygen species cause non-specific damage from which microbial resistance is unlikely to arise [27,46,47] To this latter point, aPDI has been shown to possess broad-spectrum antibacterial [23,27,48,49,50], antiviral [31,51,52,53], antifungal [46,54,55,56], and antiparasitic [57,58] properties.
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