LAUSR

Significance Studying interfacial dynamics of a single biological entity (cell, virus, or organelle) is critical for understanding microbial biofilm formation processes, developing biosensors, and designing biomaterials. However, the ability to measure the binding force between a single biological entity and surface remains a great challenge due to the hydrated feature of biological entity. In this paper, we present an optical imaging method that is able to measure the adhesion strength of single microbial cells. Unlike the existing methods with limited throughput, this method determines the adhesion strength of multiple individual cells simultaneously. This approach has the potential to contribute to a better understanding of the adhesion process at the microscopic scale and probe the biointerfaces. Probing the binding between a microbe and surface is critical for understanding biofilm formation processes, developing biosensors, and designing biomaterials, but it remains a challenge. Here, we demonstrate a method to measure the interfacial forces of bacteria attached to the surface. We tracked the intrinsic fluctuations of individual bacterial cells using an interferometric plasmonic imaging technique. Unlike the existing methods, this approach determined the potential energy profile and quantified the adhesion strength of single cells by analyzing the fluctuations. This method provides insights into biofilm formation and can also serve as a promising platform for investigating biological entity/surface interactions, such as pathogenicity, microbial cell capture and detection, and antimicrobial interface screening.