Endogenous tumor microenvironment-responsive multifunctional nanoplatforms for precision cancer theranostics

Multifunctional nanoplatforms (MFNPs) have attracted increasing attention because of their ability to integrate diverse functional diagnostic and therapeutic agents in one system. MFNPs should be biocompatible and smart, have active targeted delivery, exhibit specific target recognition and controlled release properties, exert a high therapeutic effect, and have the excellent visual diagnosing and monitoring abilities for precision cancer theranostics. Numerous strategies have been recently developed to enhance the accuracy of MFNPs for cancer theranostics. The endogenous stimuli-responsive MFNP is one of the most effective strategies and can be classified into six types based on their usage: (1) for enhancing targeted delivery, (2) for improving specific recognition and affinity performance, (3) for enhancing controlled release, (4) for synergistic multimodal diagnosis in vivo, (5) for enhanced synergistic therapy, and (6) for real-time, in situ and visual tracking of delivery, release, and therapeutic effect. Herein, these strategies are reviewed in detail. Furthermore, challenges in enhancing the accuracy of MFNPs and suggestions for further improving the performance of MFNPs are discussed to achieve real precision cancer theranostics with fewer side effects.