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

Abstract

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 10 3 to 10 5 cell/ml. Some aspects of the interaction between TiO2 and biological compounds have been discussed. This work opens up new possibilities for 1 the development of optical label-free immunosensors suitable for fast, simple and efficient analysis of Salmonella infections.

Interaction mechanism between TiO2 nanostructures and bovine leukemia virus proteins in photoluminescence-based immunosensors

“…More detailed description of deposition and characterization procedures, which were applied for the characterization of nanostructured TiO 2 /glass layers is reported in earlier our researches. 18,19 Optical characterization of the nanostructured TiO 2 /glass layers was performed by photoluminescence measurements using 355 nm solid state laser as the excitation source. Optical setup is described in detail in previous our researches.…”

“…The immobilization of biological molecules was carried out by incubation in a solution containing leukemia virus proteins -gp51, similar to the immobilization procedure described in earlier works. [18][19][20] Briey: a solution of PBS containing gp51 antigens at a high concentration was directly immobilized on the surface of TiO 2 /glass structure. Then the sample was placed into a Petri plate for the incubation in a medium saturated with water vapor at 25 C. Aer 10 min of incubation, the surface of the sample was washed with a PBS solution in order to remove not well adsorbed antigens from the surface of TiO 2 /glass structure.…”

“…19,20 Moreover, optical effects, which are registered during gp51 protein adsorption on TiO 2 /glass, also where observed and even applied in the development of photoluminescence based immunosensor for the determination of gp51 antibodies. 18,19 However in these publications no attention was paid to the nature of interaction between protein gp51 and semiconductor TiO 2 and for the prediction of the mechanism of PL-based signal generation.…”

“…The changes in the photoluminescence spectra (shi of PLmaximum and the variation of PL-signal intensity) were exploited as analytical signals for the determination of target analyte. 18,19 However the interaction mechanism of proteins with TiO 2 and the origin of the changes in the photoluminescence spectra were not discussed, although the mechanism of the interaction between semiconductor and proteins is the key in solving many of problems, which are still arising during the development of TiO 2 -based immunosensors, such as an improvement of sensitivity and selectivity. 3,13,14 This work is aiming to highlight the origin of the changes in the photoluminescence spectra of TiO 2 resulted aer the protein adsorption on its surface during the formation of biosensitive layer and aer the interaction of biosensitive layer with the analyte.…”

TiO_2-x/TiO₂-Structure Based ‘Self-Heated’ Sensor for the Determination of Some Reducing Gases

“…Electrical resistance measurements based registration is one of the simplest analytical signal registration method in comparison to many other analytical techniques, e.g. (i) the determination based on photoluminescence (PL) measurements [ 14 ] or (ii) based on more sophisticated potentiodynamic electrical/electrochemical techniques such as impedance spectroscopy [15], etc., which can be applied for analytical signal registration in the case of TiO2-based sensors.…”