Electrochemical and computational studies of bio-mimicked Ti3C2Tx MXene-based sensor with multivalent interface

Two-dimensional MXenes are the newly emerging family of nanomaterials with competitive performance for nano-device development. Surface functional groups and abundant binding sites make these materials ideal candidates for sensor applications. Herein, we report the successful fabrication of a MXene-based nano-bio device for capturing, sensing, and filtering the Escherichia coli (E. coli) bacteria. Mannose carbohydrate, which binds strongly to E.coli's fimH protein via glucan multivalent interactions, is used as the bio-receptor element. MXene's structure was engineered to guarantee efficient E. coli capturing without mannose detachment. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to control the binding and capturing processes. As a result, the final device not only presents a nano-platform for E. coli sensing in a wide dynamic range of 101-108 CFU/mL and a low detection limit of c.a. 10 CFU/mL, but also provides a nano filter to remove E.coli from water. To get a perspective on the energetics of our device, we used quantum and classical simulations to evaluate the binding energies of MXene/mannose and mannose/fimH, respectively. Anticipating our results, MXene/mannose binding energy grows as higher concentrations of hydroxyl are present on MXene's surface (|-9.90| kcal/mol for-F < |-15.68| kcal/mol for-O < |-16.60| kcal/mol for-OH). Mannose-fimH binding free energy is estimated to be around -11 kcal/mol. The overall balance of the energetics, as a result of delicate engineering of the MXene surface, is indeed reflected in our simulations. Therefore, this work suggests carbohydrate functionalized MXenes as promising candidates for water sanitation and environmental protection. (C) 2022 Elsevier Inc. All rights reserved.