The Effects of Various Surface Coatings of Gold Nanorods on Toxicity, Neuronal Localization, Microstructural Alterations, and In vitro/In vivo Biodistribution

With the development of gold nanorods (AuNRs) for a number of biomedical applications, understanding their various biological effects has become important. Surface functionalization of AuNRs is attracting increasing attention with regard to toxicity, cellular uptake, localization, therapeutic potential, and biodistribution. The aim of the study is to synthesis of stable AuNRs functionalized with polyethylenimine (PEI) and polyethylene glycol (PEG), multiparametric investigation of their cellular effects on the dorsal root ganglion (DRG) primary sensory neurones, evaluation of the in vitro/in vivo biodistribution, and toxicity. PEI and PEG surface coatings increased both biocompatibility and biodistribution of the AuNRs. With the near-infrared laser of the two-photon microscope, very strong radiations are taken from the nucleolus parts of the neurones particularly and these localizations of the AuNRs-PEI are confirmed by the transmission electron microscope images. Inductively coupled plasma mass spectrometry analysis shows the presence of AuNRs in liver, spleen, kidney, heart, blood, and brain within a 30 day period. It is observed that the surface coatings of the AuNRs significantly increase the biodistribution and biocompatibility. The surface functionalization, stability, and biocompatibility of the AuNRs are very important parameters for the potential nanotheranostic applications of AuNRs in the next studies.