Advanced nanostructured biosensors enabled by rational surface engineering for bacterial detection

Rapid, sensitive, and specific detection of bacterial pathogens is vital for ensuring public health and food safety. This study presents a rationally engineered nanostructured biosensor composed of boronic acid (BA)-functionalized indium tin oxide vertical nanowires (ITO-VNWs) for electrochemical impedance spectroscopy (EIS)-based bacterial detection. Optimizing nanowire geometry through controlled KOH etching and tailoring surface chemistry with BA modification enhanced bacterial adhesion and enabled electrical signal transduction through cis-diol-mediated boronate ester bond formation. Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) analysis confirmed improved surface-bacteria interactions, showing reduced energy barriers and stronger adhesion forces on BA-ITO-VNWs. The biosensors exhibited a broad dynamic detection range (10¹-10⁷ CFU mL^-1), rapid response within 9 min, and high specificity for Escherichia coli over Staphylococcus aureus, attributed to the abundant cis-diols on Gram-negative bacterial surfaces. Detection in spiked milk and juice samples correlated closely with results from commercial viability assays, and integration with a portable EIS chip enabled miniaturized, field-deployable diagnostics. This work highlights how nanoscale surface engineering coupled with XDLVO-based interfacial interaction modeling guides biosensor optimization, offering a versatile strategy for real-time, label-free discrimination of Gram-negative bacteria.