Nanoarchitectonics of nitric oxide releasing supramolecular structures for enhanced antibacterial efficacy under visible light irradiation

Light-controlled therapies offer a promising strategy to prevent and suppress infections caused by numerous bacterial pathogens. Excitation of exogenously supplied photosensitizers (PS) at specific wave-lengths elicits levels of reactive oxygen intermediates toxic to bacteria. Porphyrin-based supramolecular nanostructure frameworks (SNF) are effective PS with unique physicochemical properties that have led to their widespread use in photomedicine. Herein, we developed a nitric oxide (NO) releasing, biocompat-ible, and stable porphyrin-based SNF (SNF-NO), which was achieved through a confined noncovalent self -assembly process based on pi-pi stacking. Characterization of the SNFs via scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis showed the formation of three-dimensional, well-defined octahedral structures. These SNF-NO were shown to exhibit a red shift due to the noncova-lent self-assembly of porphyrins, which also show extended light absorption to broadly cover the entire visible light spectrum to enhance photodynamic therapy (PDT). Under visible light irradiation (46 J cm (2)), the SNF generates high yields of singlet oxygen (O-1(2)) radicals, hydroxyl radicals (HO), superoxide radicals (O-2(.)), and peroxynitrite (ONOO-) radicals that have shown potential to enhance antimicrobial photody-namic therapy (APDT) against Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative Escherichia coli (E. coli). The resulting SNFs also exhibit significant biofilm dispersion and a decrease in biomass production. The combination of robust photosensitizer SNFs with nitric oxide-releasing capabilities is dynamic in its ability to target pathogenic infections while remaining non-toxic to mammalian cells. The engineered SNFs have enormous potential for treating and managing microbial infections. (c) 2023 Elsevier Inc. All rights reserved.