Preparation of Microgels with Ultrahigh Payload of Various Hydrophilic and Hydrophobic Inorganic Nanoparticle Composites up to 92 wt.

Microgel loading with inorganic nanoparticle (NP) composites attracts interest for various biomedical applications. However, the encapsulation of NPs into microgels usually is a diffusion process driven by osmotic pressure, which depends highly on the concentration of NPs and causes low loading efficiency. In this work, we demonstrate preparation of microgels with ultrahigh content of various nano-objects (up to 92%, wt %) by a gelatin "casting" strategy using porous CaCO3 particles as templates. This approach could encapsulate various NPs with different charged, hydrophilic, and hydrophobic surfaces, shape, and size within microgels, without causing aggregation or change of physicochemical properties of NPs. The hybrid microgels coupled with properties of both inorganic NPs and hydrogels can be taken as an effective photothermal therapy system with great stability, reusability, and degradability and show high effective photothermal activity which is highly related to the content of NPs within microgels. The strategy of fabrication of microgels with nanocomposites is certified to be simple, facile, and low cost, which has potential applications in cancer therapy, drug delivery, catalysis, detecting system, and sewage treatment.