Improving transport efficiency for large human cells for enabling accurate determination of cellular nanoparticle...

Single-cell inductively coupled plasma-mass spectrometry (SC-ICP-MS) provides high-throughput, quantitative information on nanoparticle (NP)-cell interaction, but its application to larger mammalian cells remains limited due to the low transport efficiency (TE) provided by commercially available introduction systems. In this study, we have addressed this challenge by working at a higher spray chamber temperature (150 °C), which led to a 81-fold increase in TE for A549 human lung carcinoma cells (measured size of ∼20 μm). This observation was also validated using other cell types with different sizes and morphologies, such as red blood cells (∼6 μm) and Raji cells (∼11 μm), for which respective TE improvements of 2.3- and 13-fold were observed. Coupling the optimized setup to a time-of-flight ICP-MS (ICP-TOF-MS) unit enabled quasi-simultaneous monitoring of nearly the entire elemental mass range, allowing clear differentiation between a) cells with AuNPs, b) cells without AuNPs, and c) free AuNPs, by simultaneously monitoring the presence of cellular components (P, Zn), NPs (Au), and a DNA intercalator (Ir). The method developed was subsequently applied to study the uptake of AuNPs in cells, which is relevant for fields like drug delivery and nanotoxicology. Quantification of the number of AuNPs per cell across varying NP concentrations revealed an overdispersed Poisson distribution, consistent with theoretical expectations. Further method validation via LA-ICP-TOF-MS was used to confirm the biological relevance of the results. Overall, this study presents a robust SC-ICP-MS workflow for studying large human cells and demonstrates its utility in studying the uptake of metallic NPs in cells.