Size engineering of 2D MOF nanosheets for enhanced photodynamic antimicrobial therapy

Although porphyrin-based metal-organic frameworks (MOFs) have been widely explored as photosensitizers for photodynamic therapy, how the size will affect the light-induced catalytic activity for generation of reactive oxygen species (ROS) still remain unclear. Herein, we first report the size-controlled synthesis of two-dimensional (2D) porphyrin-based PCN-134 MOF nanosheets by a two-step solvothermal method to explore the size effect on its PDT performance, thus yielding enhanced photodynamic antimicrobial therapy. By simply controlling the reaction temperature in the synthesis process, the bulk PCN-134 crystal, large PCN-134 (L-PCN-134) nanosheets with a lateral size of 2–3 µm and thickness of 33.2–37.5 nm and small PCN-134 nanosheets (S-PCN-134) with a lateral size of 160–180 nm and thickness of 9.1–9.7 nm were successfully prepared. Interestingly, the S-PCN-134 nanosheets exhibit much higher photodynamic activity for ROS generation than that of the bulk 3D PCN-134 crystal and L-PCN-134 nanosheets under a 660 nm laser irradiation, suggesting that the photodynamic activity of PCN-134 MOF increases when the size reduces. Therefore, the S-PCN-134 nanosheets show much enhanced performance when used as a photosensitizer for photodynamic antimicrobial activity and wound healing.