Tumor microenvironment-triggered intratumoral in-situ biosynthesis of inorganic nanomaterials for precise tumor diagnostics

The severe side effects and low bioavailability of conventional chemotherapeutic drugs are the major problems that current clinical cancer treatments suffer from. In recent years, tumor microenvironment (TME)-responsive nanomedicine that design has been shown to be safe and effective for tumor diagnosis and therapy. In particular, as a branch of intratumoral nanosynthetic medicine (INSM), the in situ biosynthesis of inorganic nanomaterials within tumor in response to specific TME triggers show incomparable advantages since they can avoid clearance by innate immune system and preferably enhance the intratumoral retention, which favors the early diagnosis and treatment of tumors. In this review, we systematically summarize the recent cutting-edge advances in the intratumoral biosynthesis of inorganic nanomaterials for cancer diagnosis and treatment with an emphasis on the specific TME triggers available for triggering the process of intratumoral in-situ biosynthesis. More significantly, the rational and extraordinary design concepts and rationales are unveiled by some typical cases. Additionally, the unresolved issues, potential solutions, our perspectives and future direction are comprehensively discussed, which are expected to provide different insights into this INSM of inorganic materials and enlighten related researchers and practitioners.