Photodynamic therapy (
PDT), as an alternative approach to treat
tumors through
reactive oxygen species (ROS) produced by the activated
photosensitizers (PS) upon light irradiation, has attracted wide attention in recent years due to its low invasive and highly efficient features. However, the low hydrophilicity and poor targeting of PS limits the clinical application of
PDT. Stimuli-responsive nanomaterials represent a major class of remarkable functional nanocarriers for drug delivery. In particular, tumor microenvironment-responsive nanomaterials (TMRNs) can respond to the special pathological microenvironment in
tumor tissues to release the loaded drugs, that allows them to control the release of PS within
tumor tissues. Recent studies have demonstrated that TMRNs can achieve the targeted release of PS at
tumor sites, increase the concentration of PS in
tumor tissues, and reduce side effects of
PDT. Hence, in the present paper, we review TMRNs, mainly including pH-, redox-,
enzymes-, and
hypoxia-responsive smart nanomaterials, and focus on the application of these smart nanomaterials as targeted delivery carriers of PS in photodynamic anticancer
therapy, to further boost the development of
PDT in
tumor therapy.