Indium Phosphide Quantum Dots in Biomedicine: Photophysics, Bio-Nano Interactions, and Emerging Imaging and Therapeutic Platforms.

Indium phosphide (InP) quantum dots (QDs) have emerged as promising cadmium-free semiconductor nanomaterials with considerable potential for biomedical applications due to their tunable optical properties, high photostability, and favorable emission characteristics. In this review, the fundamental photophysical properties of InP QDs are first discussed to clarify the mechanisms governing their optical behavior and emission tunability. Subsequently, the key factors influencing their interactions at the bio-nano interface are examined, with particular attention to surface chemistry, ligand engineering, and colloidal stability in biological environments. The review further summarizes recent advances in the design and functionalization of InP QDs that enable their application in biomedical fields. Emerging applications are highlighted, including fluorescence bioimaging, light-activated therapeutic strategies such as photodynamic and photothermal therapy, and antibacterial nanoplatforms. In addition, current challenges associated with structural stability, degradation in biological media, and biosafety considerations are critically discussed. Finally, future research directions aimed at improving biocompatibility, functional performance, and translational potential are outlined. This review provides an integrated perspective on the relationship between photophysics, bio-nano interactions, and biomedical functionality of InP QDs.