Research paperToward development of optical biosensors based on photoluminescence of TiO2 nanoparticles for the detection of Salmonella

- Simple express immunosensor for the detection of Salmonella-antigens has been developed.
- Photoluminescence of TiO2 nanoparticles was applied for the detection of Salmonella-antigens.
- The immobilization of anti-Salmonella antibodies has resulted in the shift of PL-peak and increase of PL intensity.
- The Salmonella-antigen detection was performed without additional labels.
- The sensitivity of the immunosensor was determined in the range from 103 to 105 cells/ml.

Quality control of food and agriculture production is an inseparable part of human safety and well-being. Salmonella infections belong to one of the most monitored pathogens in the world, therefore advanced determination of this pathogen can decrease the risks of human diseases caused by this microorganism. In this research we introduce a novel optical immunosensor for determination of Salmonella typhimurium. The immunosensor is based on Titanium dioxide (TiO2) nanoparticles deposited on glass substrates (glass/TiO2). TiO2 nanoparticles exhibit an intense photoluminescence (PL) in the visible range of spectrum at room temperature. The direct immobilization of antibodies (anti-S-Ab) against Salmonella antigens on the surface of glass/TiO2 has resulted in the formation of glass/TiO2/anti-S-Ab-based structure, which was characterized by increased PL intensity and IR-shifted position of the PL peak in comparison to the same characteristics of glass/TiO2-based structure. The changes of the PL intensity and peak positions after interaction of the immobilized anti-S-Ab with Salmonella antigens (Salmonella-Ag) were used as immunosensor signal, allowing sensitive and selective detection of Salmonella-Ag in a label-free configuration. The sensitivity of the reported optical immunosensor towards Salmonella-Ag is in the range from 103 to 105 cell/ml. Some aspects of the interaction between TiO2 and biological compounds have been discussed. This work opens up new possibilities for the development of optical label-free immunosensors suitable for fast, simple and efficient analysis of Salmonella infections.