Carboxybetaine polymer-protected gold nanoparticles: High dispersion stability and resistance against non-specific adsorption of proteins

1-Carboxy-N,N-dimethyl-N-(2'-methacryloyloxyethyl)methanaminium inner salt (CMB) was polymerized by ATRP initiated with a disulfide difunctionalized by 2-bromoisobutyryl groups. The disulfide-carrying carboxybetaine polymer (DT-PCMB) was used for the preparation of PCMB-protected gold nanoparticles (PCMB-AuNPs) obtained by the reduction of hydrogen tetrachloroaurate (HAuCl4) in the presence of the DT-PCMB of different molecular weights at different molar ratios of DT-PCMB and HAuCl4. The sizes of gold cores in the PCMB-AuNPs tended to increase upon decreasing concentration and molecular weight of the DT-PCMB. The PCMB-AuNPs possessed a high dispersion stability, and showed a resistance against non-specific adsorption of proteins (bovine serum albumin, human serum albumin, lysozyme, and cytochrome c). Therefore, DT-PCMB is a quite suitable stabilizing ligand to prepare inert AuNPs and the PCMB-AuNPs will be useful in biomedical applications.