The development of thermal immunosensing for the detection of food-borne pathogens E. coli O157:H7 based on the novel substoichiometric photothermal conversion materials MoO 3-x NPs

A novel substoichiometric photothermal conversion materials MoO 3-x nanoparticles (4-MBA MoO 3-x NPs) was first prepared by 4-mercaptobenzoic acid modified based on the oxygen vacancy defects of molybdenum oxide and used to develop a thermal immunosensor for the detection of pathogens E. coli O157:H7. 4-mercaptobenzoic acid (4-MBA) being selected as the reducing agent functionalized surface modifier to prepare 4-MBA MoO 3-x NPs, which was an excellent photothermal conversion materials and had 42.9 % photothermal conversion efficiency under 808 nm laser. Photothermal sensor probes prepared by 4-MBA-MoO 3-x NPs being coupled with antibodies was used to develop the immunoassay for the detection of E. coli O157:H7 by means of immunomagnetic separation technology. The method could be used for semi-quantitative and quantitative determine of the E. coli O157:H7 by visual colorimetry and infrared thermal imaging. For the quantitative determination, the E. coli O157:H7 was quantified by recording the temperature response of the target bacteria combined with the nanomaterial under 808 nm laser with infrared camera. Under the optimal conditions, the low limit of detection (LOD) of the method was 14 CFU/mL with a linearity range of 1.4 × 10 1 -1.4 × 10 6 CFU/mL, and the recoveries was 82.45 %−105.08 % in real samples analysis.