One-step synthesis of linear and cyclic RGD conjugated gold nanoparticles for tumour targeting and imaging

Abstract

We developed an easy one-step method for the synthesis of linear and cyclic arginine-glycine-aspartate (RGD) conjugated gold nanoparticles (GNPs). Compared with the previously reported multistep process, our method is simple, time-efficient, and cost-effective. Interestingly, the RGD peptides can function as reducing, protecting and tumour targeting agents and the prepared GNPs possess good stability and good biocompatibility. The uptake of RGD–GNPs by human tumour cells was assessed by dark-field light scattering imaging and transmission electron microscopy (TEM). Both types of RGD–GNPs can specifically target the melanoma A375 cells better than the breast cancer MCF-7 cells, which express the integrin α_vβ₃ at low level. We also compared the cellular uptake ability between the linear and cyclic RGD conjugated GNPs quantitatively. In order to validate the cellular uptake mechanism, the competitive inhibition assay was performed. Various important results indicated that the activity of the RGD peptides to specifically target tumour cells was not influenced noticeably after conjugation with GNPs.