Matrix metalloproteases-responsive nanomaterials for tumor targeting diagnosis and treatment

Tumour poses tremendous challenges to mankind. In various tumours, matrix metalloproteases (MMPs) are ubiquitously over expressed and participate throughout the process of tumour development. MMPs are commonly used as internal stimuli, and MMPs-responsive nanomaterials are classified into three categories according to the drug delivery process: administration and distribution to tumour, intratumoural distribution and cell internalisation, and specific drug release. First, MMPs-sensitive polyethylene glycol (PEG) de-shielding and activatable cell penetrating peptides were developed to improve the blood circulation time of drug delivery systems, thereby, enhancing tumour or stroma cells recognition and penetration. Following tumour recognition, the MMPs-sensitive and size- or morphology-changeable nanoparticles (NPs) could highly accumulate and penetrate into tumour. Lastly, several MMPs-sensitive drug release strategies were feasible for both small molecule drugs and macromolecule drugs. In conclusion, recent novel advances of MMPs-responsive nanomaterials in tumour targeting diagnosis and treatment were highlighted in this review.