Chitosan-graft-Poly(L-lysine) Dendron-Assisted Facile Self-Assembly of Au Nanoclusters for Enhanced X-ray Computer Tomography Imaging and Precise MMP-9 Plasmid shRNA Delivery

Au nanoclusters (Au NCs) are materials that hold great promise in biomedical applications due to their improved photophysical properties. However, the current nonthiolate polymer-based self-assembly methods for preparing Au NCs face drawbacks of usage of environmentally unfriendly reducing reagents or nonbiocompatible polymers, which largely hamper their more extensive biomedical use. In this work, biocompatible chitosan-graft-poly(L-lysine) (CPL) dendrons are designed and synthesized based on a simple azide-alkyne cyclization reaction for facile preparation of Au@CPL NCs in one step. The obtained Au@CPL NCs exhibited enhanced computer tomography imaging property as compared with clinically used iohexol (Omnipaque) and displayed high delivery efficiency for matrix metalloproteinase-9 plasmid shRNA (pMMP-9). After surface functionalization by cyclic arginine-glycine-aspartic (Arg-Gly-Asp, RGD), a peptide that specifically targets alpha(v)beta(3) integrin overexpressed by cancer cells, the resultant Au@CPL-RGD/pMMP-9 complex can precisely and efficiently inhibit tumor growth both in vitro and in vivo. Our work provides a novel strategy to fabricate Au NCs with enhanced biorelevant properties for more efficient cancer diagnosis and therapy.