Gold nanoparticle decorated pH-sensitive polymeric nanocontainers as a potential theranostic agent

A promising biocompatible auto-fluorescent and pH-sensitive drug delivery system has been developed based on polymeric hollow nanospheres with embedded gold nanoparticles. [Display omitted] •Gold functionalized P(MAA-co-MBA-co-AA) (CSNs) microspheres.•Auto-fluorescence of gold nanoparticles.•Sustained drug release at acidic pH.•Negligible cytotoxicity of drug free nanocontainers over both MCF7 and HEK-293 cell lines. A pH-sensitive system of hollow P(MAA-co-MBA-co-AA) nanocontainers (NCs) modified with gold nanoparticles (GNCs) has been developed for theranostic applications, drug delivery and real time monitoring through imaging. The GNCs were synthesised by the distillation precipitation copolymerization procedure followed by in situ synthesis and embodiment of gold nanoparticles on the polymeric matrix (CSNs). Separately, citrate capped gold nanoparticles (GNPs) were also synthesized and compared with the GNCs for their fluorescence and cellular localization ability. The GNCs were tested for their drug loading and release behavior in response to the anticancer drug doxorubicin (DOX) at different pH values. Sustained drug release was observed at acidic pH. The viability of MCF-7 breast cancer cells and HEK-293 human embryonic kidney cells in relation to the GNCs, GNPs, GNC@DOX and DOX was also evaluated. GNCs and GNPs at the tested concentrations did not inhibit proliferation at either cell lines, whereas the GNCs@DOX presented comparable results. Cellular migration of MCF-7 cells treated with GNCs or GNPs was evaluated through the scratch-wound healing assay but no significant inhibition was detected. GNCs’ and GNPs’ fluorescence ability was exploited for assessing cellular localization through confocal laser scanning microscopy. GNCs after only 1 h of treatment were found in the cytoplasm of MCF7 cells, whereas GNCs@DOX were localized in the nucleus; the desirable site of action of DOX.