Zeta potential: An efficient and cost-effective alternative for investigating cell-surface interactions

Monitoring and quantifying cell-surface interactions is important for drug discovery and understanding the physiological and pathological activities of cells. While techniques like Enzyme-linked immunosorbent assay (ELISA), Fluorescence resonance energy transfer (FRET), and Atomic force microscopy (AFM) have proven effective in this area, these technologies are associated with the cost of capital equipment, extended turnaround time, and specialized trained personnel. Moreover, they may not accurately reflect what is happening in living systems, e.g., live cells.

To mitigate these concerns, we introduce Zeta potential analysis, which offers a cost-effective, real-time, and label-free quantitative method to assess the shift of surface charge induced by molecular interactions. This approach is particularly valuable for evaluating receptor ligand binding dynamics. In this study, we provided two examples of measuring biological response to the external stimuli in living systems using zeta potential. The first example demonstrated how per- and polyfluoroalkyl substances (PFAS) interact with human mammary cells, MCF10A and MDA-MB-231. The second example determined how nanoparticles (NPs) interact with bacteria, Escherichia coli, Salmonella typhi, and Bacillus subtilis. These interactions were benchmarked by paired zeta potential results with immunofluorescent staining using standard antigen-antibody staining on live cells.

Our results of zeta potential to prove cell surface interactions are obtained within a 15 min time period. The supply cost of a single experiment is <$5. We demonstrated that zeta potential analysis is a powerful and versatile technique for investigating cell-surface interactions. It enables real-time monitoring of molecular binding events and is broadly applicable across living systems, including mammalian and bacterial cells.

The benchmarking results showed that even subtle biological responses that shift the surface charge of living cells can be clearly detected. To conclude, this capability of detecting subtle changes allows for confirmation of ligand-receptor interaction mechanisms and provides early and reliable insights to justify further investment in costly research methods during pre-clinical drug development.