Polymer-metal hybrid nanoparticles as a novel gene vector for cancer imaging and therapy

Abstract

Gene therapy uses exogenous genes for therapeutic functions and is promising for treating cancer. Therapeutic genes are delivered into cells and must overcome various barriers before reaching the target. Due to problems with viral vectors, non-viral vectors are developed for gene delivery. Nanoparticles (NPs) such as gold NPs are potential nanovectors owing to their various advantages. In this study, hybrid NPs with an Au-Ag bimetallic core and a folic acid-chitosan shell (Au-Ag@CS-FA), which can provide cancer targeting and imaging functions, were investigated as a new nanovector. Highly branched Au-Ag NPs were synthesized as core and FA-conjugated CS formed the shell in Ag@CS-FA NPs. Tests showed sufficient FA molecules in the CS-FA shell, which would provide the ability for targeting folate receptor overexpressed cancer cells. For cancer detection, rhodamine B was embedded in Au-Ag@CS-FA NPs, which would emit SERS signals. Plasmid DNA encoding enhanced green fluorescent protein with a CMV promoter (pEGFP) was used as model gene. NP/pEGFP complexes at different ratios were prepared to investigate effects of incubation time and pH on the binding ability of Au-Ag@CS-FA NPs with pEGFP. Results showed Au-Ag@CS-FA NPs were stable, had good biocompatibility and possessed strong DNA binding ability in the acidic environment. SERS signals given by Ag@CS-FA NPs enabled cancel cell imaging.