Label-free microfluidic device reveals single cell phagocytic activity and screens plant medicine rapidly

Phagocytic activity is an extremely important indicator that evaluates medicinal effects related to the immune system and functions to investigate the mechanism of how a drug works under conditions such as immunological regulation, immune tolerance, inflammation, cancer, etc. Current techniques based on flow cytometry, fluorescence imaging or numbering CFUs after cell lysis for detecting phagocytosis suffer from long terms of bacteria culturing and complex preparation steps for fluorescent labeling or require a large amount of cell samples to be tested. This study aims at developing a simple and fast method for testing the phagocytic activity of unlabeled and native cells, taking advantage of very high-resolution direct current insulator-based dielectrophoresis (DC-iDEP). The properties of cells are characterized by native whole cell biophysical properties. This strategy not only eliminates the time-consuming bacterial culture work after cell lysis, but also lowers the expenses of bacteria labeling. The introduction of microfluidics reduces the sample volume or reagent needed. The analysis of the biophysical property distributions of native cells and medicine treated cells may lead to a less expensive and rapid tool for evaluating medicinal effects. Furthermore, berberine was investigated for decreasing the phagocytic activity of macrophages and used for comparison of activities. This study works on establishing a label-free, unbiased, and non-destructive method to determine cell phagocytic activity and investigate its use in evaluating medicinal effects on phagocytosis in a single step within a short time.

Automated summary

This study aims to develop a simple and fast method for testing the phagocytic activity of unlabeled and native cells using high-resolution direct current insulator-based dielectrophoresis (DC-iDEP). The method reduces the time and cost of bacterial culture and fluorescent labeling, and the introduction of microfluidics reduces sample volume and reagent needed. The analysis of the biophysical property distributions of cells may lead to a cheaper and faster tool for evaluating medicinal effects. Furthermore, the study investigates the effect of berberine on reducing macrophage phagocytic activity for comparison.