Label-free detection of Vibrio parahaemolyticus using a solid-state pH sensor

Vibrio parahaemolyticus is a prevalent foodborne pathogen which can cause acute gastroenteritis, septicemia and even death. Therefore, rapid and accurate detection of Vibrio parahaemolyticus is of critical importance for ensuring food safety and public health. Herein, we report the development of a pH-ultrasensitive electrochemical sensor based on iridium oxide (IrO) for the real-time and label-free detection of Vibrio parahaemolyticus. The IrO was electrodeposited on the indium tin oxide (ITO) electrode using a silica nanochannel membrane as the template. The obtained IrO/ITO electrode functions as a solid-state pH sensor and displays a super-Nernstian response with a sensitivity over 78 mV/pH, enabling the effective detection of hydrogen ions released by hydrogel-based loop-mediated isothermal amplification (LAMP) and realizing the quantification of Vibrio parahaemolyticus. Owing to the confinement effect of the unique porous structure of hydrogel, the efficiency of LAMP reaction is significantly promoted, thus achieving the rapid detection of Vibrio parahaemolyticus within 30 min with a detection limit as low as 1.93 copies/reaction. Furthermore, the electrochemical sensor is fully sealed and free of aerosol contamination. We believe that the sensor can be potentially employed for the detection of other pathogens and in point-of-care testing diagnostics.