Label-Free and High-Throughput Quantification of Nanoparticle-Cell Interactions at the Single-Cell Level with Flow Cytometry

Understanding nanoparticle-cell interactions at the single-cell level is essential for designing next-generation nanomedicines. Here, we explored flow cytometry as a single-cell technique for label-free quantification of nanoparticle-cell interactions. We demonstrated the use of conventional flow cytometry-based side-scattering signals to quantify interactions between nanoparticles and individual cells. We corroborated our findings qualitatively with optical super-resolution microscopy and quantitatively with elemental mass spectrometry. Using a broad, multiparameter workflow, we analyzed >10,000 single cells per minute to evaluate how nanoparticle size, composition, surface chemistry, and concentration affect cellular interactions, and we leveraged this approach to quantify nanoparticle uptake kinetics at the single-cell level. We further validated our findings using super-resolution expansion microscopy and single-particle inductively coupled plasma mass spectrometry, and extended the applicability of this workflow to mixed-cell and coculture in vitro cell models. Our demonstrated workflows enable a quantitative understanding of nanoparticle-cell interactions for the rational design of next-generation nanomedicines that are safer, more effective, and more efficient.