Chemical and green synthesis of gold nanoparticles for mRNA delivery in vitro

Nanotechnology has paved the way for novel treatment strategies for diseases such as cancer. While chemical synthesis of nanoparticles (NPs) can introduce toxic and expensive reducing reagents, green synthesis offers an alternative with dual reducing and capping properties. Curcumin exhibits favourable pharmacological properties, enabling synergism with the therapeutic cargo. This study aimed to compare green and chemically synthesised gold NPs for the delivery of FLuc-mRNA in vitro. Chemical and green synthesised AuNPs were produced using trisodium citrate and curcumin, respectively, and functionalised with poly-L-lysine (PLL) and polyethylene glycol (PEG). The NP:mRNA nanocomplexes were characterised using nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and UV-visible spectroscopy. Various mRNA binding studies assessed the optimal mRNA binding, compaction, and protection of the mRNA. All AuNPs were small (<150 nm) and had good colloidal stability, mRNA binding, and protection. The MTT (3-[4,5-dimethylthiazol-2-yl]-2.5-diphenyltetrazolium bromide) assay showed favourable cell viability, with significant transgene expression noted using the luciferase reporter gene assay. Higher transfection was achieved in the human cervical carcinoma (HeLa) than in the breast adenocarcinoma (MCF-7) and embryonic kidney (HEK293) cells. Both chemically and curcumin-synthesised AuNPs displayed similar activity in all cells, with curcumin-capped AuNPs marginally better at the same concentration.