Synthesis and functionalization of d-PLL-PEG-FA coated gold nanoparticles for siRNA delivery in human prostate cancer

Abstract

Herein, we describe, a simple method for the synthesis of dendrigraft poly-L-lysine (d-PLL) coated gold nanoparticles in water (AuNPs-d-PLL) as potential vehicles of siRNA delivery to prostate cancer cells, PC3-PSMA. AuNPs-d-PLL with diameters ranging between 50 ̶ 130 nm have been synthesized in aqueous solutions using d-PLL (7 KD) as a capping ligand and L-ascorbic acid as a reducing agent. The size of the resulting AuNPs was found to depend on several parameters, such as the concentrations of gold salt, reducing agent, and d-PLL. The obtained AuNPs-d-PLL were characterized using UV-visible spectroscopy (UV-vis) and Dynamic Light Scattering (DLS). Increasing the concentration of the gold precursor (HAuCl4) resulted in an overall increase in AuNP size (Z avg). On the other hand, an increase in reducing agent concentration resulted in a decrease in average particle size. Concerning the increase in capping agent (d-PLL), no significant change on AuNPs size was observed. Furthermore, the ability to PEGylate the AuNPs-d-PLL with SH-PEG-OCH3 and SH-PEG-Folate was demonstrated via DLS and zeta potential measurements, their capacity to complex siRNA was verified using DLS and gel electrophoresis. Finally, transfer of AuNPs-d-PLL-PEG-FA.siRNA to PC3-PSMA cells was investigated via FACS, laser scanning microscopy, and Z-stacking.