Targeted Intracellular Protein Delivery Based on Hyaluronic Acid-Green Tea Catechin Nanogels.

A novel ternary nanogel based on the self-assembly of hyaluronic acid-epigallocatechin gallate conjugates (HA–EGCG), linear polyethylenimine (PEI) and Granzyme B (GzmB) in an aqueous environment was developed for the targeted intracellular delivery of GzmB into cancer cells. Lysozyme-encapsulated HA–EGCG nanogels were first prepared and characterized. HA–EGCG nanogels exhibited smaller particle sizes and a more homogeneous size distribution than the HA counterpart. Fluorescence quenching and lysozyme activity studies revealed that EGCG moieties facilitated protein binding through physical interactions and led to the formation of stable nanogels. When CD44-overexpressing HCT-116 colon cancer cells were treated with GzmB-encapsulated HA–EGCG nanogels in vitro, a significant cytotoxic effect was observed. Caspase assays and intracellular trafficking studies confirmed that cell death was due to apoptosis triggered by the delivery of GzmB to the cytosol of those cells. In comparison, little cytotoxic effect was observed in CD44-deficient cells treated with GzmB-encapsulated HA–EGCG nanogels. This study highlights the potential utility of HA–EGCG as effective intracellular protein carriers for targeted cancer therapy.