A Simple Synthesis of Polymer Coated Gold and Silver Nanoparticles in Water for Potential Use in Biomedical Applications

K. Rahme, G. Minassian, E. Ghanem, M. Sarkis, M. Nakhl, R. El Hage, E. Souaid, J.D. Holmes
Notre Dame University (Louaize),

Keywords: gold nanoparticles, silver nanoparticles, ascorbic acid, polymers, polyethylene glycol (PEG), neutrophils, water


Herein we describe a simple method for the synthesis of highly stable gold (Au) and silver (Ag) nanoparticles (NPs) in water. Ag and Au NPs of different surface charges (positively charged, negatively charged, or nearly neutral) and sizes were obtained using ascorbic acid as a reducing agent and multiple polymers such as chitosan, Poly-L-Lysine (PLL), Polyvinyl alcohol (PVA), Polyethylene-Glycol (PEG) or sodium citrate as stabilizing ligands [1, 2]. The obtained NPs were characterized using UV-visible spectroscopy (UV-vis), Dynamic Light Scattering (DLS), and Zeta Potential (ζ) measurements [3]. Physicochemical characterization has shown that the NPs exhibit optical size and element-dependent properties. Moreover, DLS analysis proved that the colloidal solutions were monodispersed (single size distribution) with a polydispersity index (PDI) from 0.08 to 0.22, and a zeta potential varying from positive (~+45 mV), nearly neutral or negative (~-40 mV) depending on the type of coating. On the other hand, to stress on their potential use in biomedical applications, AuNPs with different coating (PLL, PVA and PEG) were tested on whole human blood samples, specifically on neutrophils using a Neutrophil Function Test (NFT) [4]. NFT test is used to determine whether differently charged AuNPs might result in variant activation efficiency of neutrophils. Neutrophil activation was tracked using Nitrotetrazolium Blue (NBT) dye reduction and formazan granule formation upon reactive oxygen species release. As a positive control, Phorbol Myristate Acetate (PMA) was used as stimulant. Interestingly, results show that Au NPs-PVA with a slight negative charge (-15 mV) and PEgylated AuNPs-PLL (AuNPs-PLL-PEG) with a slight positive charge (~+ 9 mV) were found to be the least detected by neutrophils. However, positively charged AuNPs-PLL (+30 mV) induced a significant activation of ~70 % of the neutrophil pool relative to PBS (negative control). Furthermore, AuNPs-PLL resulted in increasing cell size population that was detected by flow cytometry (data not shown). Finally, cytotoxicity assay of positively charged AuNPs-PLL was performed on various prostate cancer cell lines, and did not show any signs of toxicity even upon high doses treatment. Based on our findings we support the use of PEGylated AuNPs-PLL as suitable shuttle vectors for in vitro and in vivo delivery of nucleic acids to prostate cancer cells [5] and cancer theranostics [6]. Acknowledgments: We acknowledge financial support from the National Council for Scientific Research Lebanon (CNRS-L-GRP2015-3538). References [1] K. Rahme et al. ThechConnect Brierfs, 2017, ISBN 978-0-9975117-8-9, Chapter 4, 159-162. [2] K. Rahme et al. RSC Adv., 2013, 3, 6085–6094 and RSC Adv., 2017, 7, 8798–8799 [3] K. Rahme et al. Colloids and Surfaces B: Biointerfaces, 2015, 135, 604–612 [4] A.W. Segal, The Lancet, 1974, 304, 1248–1252 [5] C. M O’Driscoll et al. J. Mater. Chem. B, 2016, 4, 2242–2252 [6] J. Guo, K. Rahme et al. Int J Nanomedicine. 2017, 12, 6131–6152