Remodeling Tumor Microenvironment by Multifunctional Nanoassemblies for Enhanced Photodynamic Cancer Therapy

Photodynamic therapy (PDT) is a clinically implemented modality to tackle intractable diseases, including cancer. Nevertheless, its efficacy is largely compromised by some resistance factors from the complex tumor microenvironment (TME) with various biological barriers. Inspiringly, recent development in nanotechnology has revitalized photodynamic cancer therapy based on rationally designed nanoplatforms that can boost PDT through remodeling TME. Here, we first provide an overview of the microenvironment in solid tumors and the PDT-resistance factors therein. On this basis, we discuss strategies to design multifunctional nanoassemblies and underlying working mechanisms to enhance photodynamic cancer therapy by modulating tumor vasculatures, extracellular matrix, hypoxia, antioxidant defense, and immune suppression. Finally, we highlight the potential and challenges in this burgeoning research field.