Core-shell structured nanoparticles for photodynamic therapy-based cancer treatment and related imaging

Photodynamic therapy (PDT) is an emerging noninvasive therapy modality for treating cancer diseases. However, conventional PDT suffers from poor stability of organic photosensitizers, limited tissue penetration depth of excitation light and hypoxic tumor microenvironment, which hinders its modern clinical applications. The combination of PDT and nanotechnology is becoming a promising technology to tackle these troubles. Core-shell structured nanoparticles are of great interest as they can integrate the functionalities of individual components into one structure and exhibit improved physical and chemical properties that are different from the single component. Therefore, many efforts have been paid to develop core–shell structured nanoparticles for PDT of cancer. This review provides a panorama of the latest achievement in the developments of core–shell structured nanoparticles for PDT-based cancer treatment and related imaging. Concretely, this review starts with the categories of core–shell structured nanoparticles, followed by the functions of these nanoparticles in PDT of cancer, including photosensitizer delivery vehicle, energy transducer, photosensitizer and hypoxic tumor microenvironment modulator. Then the applications of core–shell structured particles for photodynamic synergistic therapy of cancer are highlighted as well as their imaging applications as contrast agents. Finally, perspectives on the major challenges and opportunities are presented for better developments in the future research.