In-vitro Safety Assessment of Ultrasmall Gold Nanoparticles for Preclinical Drug Delivery Applications

Background: The development of safe and biocompatible nanoparticles has always been a major concern in nanomedicine applications. Various studies on the size-dependent toxicity of nanoparticles have been reported but are still controversial. The potential of small-sized nanoparticles can be utilized for imaging and diagnostics. However, insufficient toxicity data on these nanoparticles prevents researchers from utilizing their potential in diagnostics. More studies are needed on the toxicity of small-sized nanoparticles to present unanimous report for safe systemic use. The present study aimed to investigate the toxicity concerns of very small-sized AuNPs (2 ¦plusmn; 0.5 nm, 5 ¦plusmn; 1 nm, and 10 ¦plusmn; 2 nm) and provide a platform for their safe in vivo use.Methods: The cellular interactions of these three small-sized AuNPs with regard to cytotoxicity were investigated on hepatocellular carcinoma (HepG2) and epithelial kidney (HEK-293) cell lines. The cytotoxicity investigation of both cell lines was done through MTT assays, PI & DAPI, and cytology. Cellular stress was investigated by Catalase, TBARS, GSH, SOD & ROS parameters. The AuNPs incubated cells were also assessed for immunogenicity by ELISA, protein interaction by BSA, and cellular internalization by TEM (Edax).Results: All three-sized AuNPs were not toxic on cell viability, apoptosis, necrosis, or cytology assessment. No oxidative stress was noted in both cell types in the presence of 2 and 5-nm-sized AuNPs, whereas 10 nm-sized AuNPs showed little oxidative stress. AuNPs of size 2 and 5 nm were immunologically inert, but 10 nm-sized AuNPs elicited interleukin (IL-4 and IL-10) and interferon IFN gamma response. AuNPs of sized 2 nm showed 4 times the adsorption of albumin protein as compared to AuNPs of sized 5 nm. The TEM micrographs and peak of gold in the Edax graph confirmed the presence of AuNPs in cells.Conclusion: Our results are suggestive of utilizing the potential of these three-sized AuNPs safely in preclinical drug delivery applications.