The development of thermal immunosensing for the detection of food-borne pathogens E. coli O157:H7 based on the novel substoichiometric photothermal conversion materials MoO3-x NPs

A novel substoichiometric photothermal conversion materials MoO3-x nanoparticles (4-MBA MoO3-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 MoO3-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-MoO3-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 x 10(1)-1.4 x 10(6) CFU/mL, and the recoveries was 82.45 %-105.08 % in real samples analysis.

Automated summary

A novel substoichiometric photothermal conversion material MoO3-x nanoparticles (4-MBA MoO3-x NPs) were successfully prepared and used to develop a thermal immunosensor for detecting the pathogen E. coli O157:H7. By utilizing immunomagnetic separation technology, the photothermal sensor probes coupled with antibodies enabled semi-quantitative and quantitative determination of E. coli O157:H7 with high efficiency and accuracy, showing great potential for practical applications.