Tracing size and surface chemistry dependent endosomal uptake of gold nanoparticles using surface-enhanced Raman scattering.

Surface-enhanced Raman scattering (SERS) based-single cell analysis is an emerging approach to obtain molecular level information from molecular dynamics in a living cell. In this study, endosomal biochemical dynamics was investigated based on size and surface chemistry dependent uptake of gold nanoparticles (AuNPs) on single cells over time using SERS. MDA-MB-231 breast cancer cells were exposed to 13 nm and 50 nm AuNPs and their poly-Adenine oligonucleotide modified forms by controlling the order and combination of AuNPs. The average spectra obtained from 20-single cells were analyzed to study the nature of the biochemical species or processes taking place on the AuNPs surfaces. The spectral changes, especially from proteins and lipids of endosomal vesicles, were observed depending on the size, surface chemistry, and combination as well as the duration of the AuNP-treatment. The results demonstrate that SERS spectra are sensitive to trace biochemical changes not only the size, surface chemistry and aggregation status of AuNPs but also their endosomal maturation steps over time, which can be simple and fast way for understanding the AuNPs behavior in single cell and useful for the assisting and controlling of AuNPs-based gene or drug delivery applications.