Unraveling the Potential of Photochemical Nanoplatforms in Tumor Microenvironments: Therapeutic Strategies for Gastrointestinal Malignancies

Gastrointestinal (GI) malignancies have caused tremendous disease burden around the world; however, conventional therapy strategies, such as radiotherapy, chemotherapy, and immunotherapy, have achieved limited efficacy in the diagnosis and treatment. In further exploration of GI tumors, the complexity and heterogeneity of the tumor microenvironment (TME) have been increasingly recognized. Appropriate strategies to modulate the TME are necessary to enhance the therapeutic effect. Photosensitizers (PSs) are chemical substances that are activated at specific wavelengths of light to initiate photodynamic effects. Nanotechnology provides a platform for the targeted delivery of PSs and small-molecule drugs, enabling precise targeting and remodeling of the TME. In this review, we summarize the principles and mechanisms of photochemical reactions and elaborate on the effect of photochemical nanoplatforms in modulating the TME of GI tumors. Finally, we discuss the potential value of photochemical nanoplatforms for diagnosing GI malignancies.