Carbohydrate-protein interactions studied by solid-liquid contact electrification and its use for label-free bacterial detection

Label-free and rapid detection of pathogenic microorganisms carry an utmost importance for human health as well as environmental monitoring and diagnostics purposes. However, concurrent bacterial detection techniques are either time consuming or associated with expensive reagents and sophisticated equipments. Herein, surface engineered nanoparticles and solid-liquid contact electrification are applied to study the carbohydrate-protein interactions and to develop a self-powered and label-free nanosensor for the detection of Escherichia coli (E. coli) for the first time. D-Mannose functionalized gold nanoparticles (m-Au NPs) and PBS (Phosphate buffer saline) buffer are utilized as the solid triboelectric sensing layer and contact liquid, respectively. The transferred charges generated from the contact electrification of m-Au NPs and PBS result in self-powered electric outputs as signals to investigate the interaction between D-mannose and concanavalin A (Con A). In addition, m-Au NPs also show its ability to specifically recognize the FimH of type 1 pili in E. coli and enable the triboelectric nanosensor (TENS) with selective and sensitive detection towards E. coli. The sensing mechanism has been fully studied and supported in light of surface modification mediated change in interfacial charge transfer phenomena. Attachment of Con A or E. coli decreases the work function of the solid triboelectric sensing layer leading to the enhancement of output voltage and thereby provides the necessary sensing platform. Moreover, the developed TENS shows the reusable potential and can detect E. coli in a wide range from 2 × 104 to 2 × 107 CFU/ml with a limit of detection (LOD) of 4 × 103 CFU/ml. The current work highlights the bright prospect of TENS as a new prototype of sensing technology for label-free and rapid analysis of carbohydrate-protein interactions as well as other pathogenic microorganisms.