Gold nanocluster-conjugated amphiphilic block copolymer for tumor-targeted drug delivery

Two kinds of core-shell structured multifunctional nanocarriers of gold nanoclusters (Au NCs) as core and folate (FA)-conjugated amphiphilic hyperbranched block copolymer as shell based on poly(L-lactide) (PLA) inner arm and FA-conjugated sulfated polysaccharide (GPPS-FA) outer arm (Au NCs-PLA-GPPS-FA) were synthesized for targeted anticancer drug delivery. The structure and properties of Au NCs-PLA-GPPS-FA copolymers were characterized and determined by ¹H NMR spectrum, FT-IR spectra, dynamic light scattering (DLS), fluorescence spectroscopy, and transmission electron microscopic (TEM) analyses. The anticancer drug, camptothecin (CPT) was used as a hydrophobic model anticancer drug. In vitro, two kinds of the nanocarriers presented a relatively rapid release in the first stage (up to 1 h) followed by a sustained release period (up to 15 h), and then reached a plateau at pH 5.3, 7.4, and 9.6. The release results indicated that CPT release from two kinds of the nanocarriers at pH 9.6 was much greater than that at both pH 5.3 and 7.4. The cytotoxicity studies showed that the CPT-loaded nanocarriers provided high anticancer activity against Hela cells. Furthermore, nanocarriers gained specificity to target some cancer cells because of the enhanced cell uptake mediated by FA moiety. The fluorescent images studies showed that the nanocarriers could track at the cellular level for advance therapy. The results indicated that the Au NCs-PLA-GPPS-FA copolymers not only had great potential as tumor-targeted drug delivery carrier, but also had an assistant role in the treatment of cancer.