Synergistic photogeneration of nitric oxide and singlet oxygen by nanofiber membranes via blue and/or red-light irradiation: Strong antibacterial action.

New functionalities were added to biocompatible polycaprolactone nanofiber materials through the co-encapsulation of chlorin e6 trimethyl ester (Ce6) photogenerating singlet oxygen and absorbing light both in the blue and red regions, and using 4-(N-(aminopropyl)-3-(trifluoromethyl)-4-nitrobenzenamine)-7-nitrobenzofurazan, NO-photodonor (NOP), absorbing light in the blue region of visible light. Time-resolved and steady-state luminescence, as well as absorption spectroscopy, were used to monitor both photoactive compounds. The nanofiber material exhibited photogeneration of antibacterial species, specifically nitric oxide and singlet oxygen, upon visible light excitation. This process resulted in the efficient photodynamic inactivation of E. coli not only close to nanofiber material surfaces due to short-lived singlet oxygen, but even at longer distances due to diffusion of longer-lived nitric oxide. Interestingly, nitric oxide was also formed by processes involving photosensitization of Ce6 during irradiation by red light. This is promising for numerous applications, especially in the biomedical field, where strictly local photogeneration of NO and its therapeutic benefits can be applied using excitation in the "human body phototherapeutic window" (600-850 nm). Generally, due to the high permeability of red light, the photogeneration of NO can be achieved in any aqueous environment where direct excitation of NOP to its absorbance in the blue region is limited.

Magnetically Separable Photoactive Nanofiber Membranes for Photocatalytic and Antibacterial Applications.

We have prepared photoactive multifunctional nanofiber membranes via the simple electrospinning method. The antibacterial and photocatalytic properties of these materials are based on the generation of singlet oxygen formed by processes photosensitized by the tetraphenylporphyrin encapsulated in the nanofibers. The addition of magnetic features in the form of magnetic maghemite (γ-Fe2O3) nanoparticles stabilized by polyethylenimine enables additional functionalities, namely, the postirradiation formation of hydrogen peroxide and improved photothermal properties. This hybrid material allows for remote manipulation by a magnetic field, even in hazardous and/or highly microbial contaminant environments.