Enhancing photodynamic inactivation via tunning spatial constraint on photosensitizer

Abstract

The critical factor of spatial constraint, provided by the external confinement (e.g., matrix), is often overlooked during photodynamic inactivation, despite playing a crucial role in determining the molecular photophysical process and subsequent antipathogen performance. Here, as a proof-of-concept model, we employed two types of polymers with varying interaction energies with dopants to investigate the intrinsic relationship between spatial constraint and the essential excited-state behaviors of doped photosensitizer (4-(2-(5-(4-(diphenylamino)phenyl)thiophen-2-yl)ethyl)-1-methylquinolin-1-ium iodine, TPP). Through experimental investigation and theoretical calculations, we found that TPP tends to remain in the excited state for a shorter dwell time under weaker spatial constraints due to less restricted molecular motion in polyurethane (PU) nanofibers. Consequently, the singlet oxygen (1O2) generated from doped-TPP shows a 9.23-fold enhancement in PU than in the polyvinylchloride (PVC) matrix. Under light irradiation, the PU@TPP nanofiber can efficiently eliminate the coronavirus MHV-A59 (⩾99.9997%) at a 220,000-fold higher concentration than the infected space. Its antibacterial efficacy has also been demonstrated, with a killing rate of ⩾99%.