Size/charge dual-conversion nanoparticle-gelatin composite nanocluster as well as preparation method and application thereof

The invention discloses a size/charge dual-conversion nanoparticle-gelatin composite nano-cluster as well as a preparation method and application of the size/charge dual-conversion nanoparticle-gelatin composite nano-cluster. The preparation method comprises the following steps: firstly, modifying gelatin with a targeting ligand and an anhydride compound or modifying the gelatin with the anhydride compound, so that the gelatin has a negative-to-positive charge conversion characteristic from a neutral state to a weak acid pH (Potential of Hydrogen) state; the preparation method comprises the following steps: preparing positively charged drug-loaded nano-particles by a sol-gel method or a nano-precipitation method; and finally, carrying out electrostatic assembly on the modified gelatin and the nano-particles to obtain the nano-particle-gelatin composite nano-cluster. The composite nano-cluster utilizes the dual responsiveness of the modified gelatin to pH and enzyme in a disease microenvironment, can release p