Enhancing photodynamic inactivation via tunning spatial constraint on photosensitizer

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 (O-1(2)) 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%.