Abstract
The research aim of this work is to develop a simple and highly sensitive optical biosensor for detection of mycotoxins. This sensor is built on a planar waveguide operating on the polarization interferometry principle, i.e., detecting a phase shift between p- and s-components of polarized light developed during the binding of analyte molecules. The operation of the proposed sensor is similar to that of a Mach–Zehnder interferometer, while its design is much simpler and it does not require splitting the waveguide into two arms. The refractive index sensitivity of the polarization interferometer sensor was in the range of 5200 radians per refractive index unit (RIU). Several tests were conducted to detect ochratoxin A (OTA) at different concentrations in direct immunoassay with specific antibodies immobilized in the sensing window. The lowest concentration of OTA of 0.01 ng/mL caused a phase shift of nearly one period. The results obtained prove high sensitivity of the sensors, which are capable of detecting even lower concentrations of mycotoxins at the ppt (part-per-trillion) level.
Highlights
At present, the detection of toxins is one of the main tasks for environmental science, security, agriculture, the food industry, and medicine
Worldwide legislation sets quite strict limits on mycotoxin content in food and feed, typically at the ppb concentration level [2], which makes the detection of small mycotoxin molecules a difficult task
planar waveguide (PW) sensors sensors can can be be estimated estimated as as aa gradient gradient of of the the above above linear dependence: linear dependence: The refractive index sensitivity (RIS) of PW sensors can be estimated as a gradient of the above linear dependence:
Summary
The detection of toxins is one of the main tasks for environmental science, security, agriculture, the food industry, and medicine. There is particular interest in detection of mycotoxins, products of the metabolism of numerous fungi species, which appear to have toxic, carcinogenic, and hormone-disruptive effects in humans [1]. Worldwide legislation sets quite strict limits on mycotoxin content in food and feed, typically at the ppb (part-per-billion) concentration level [2], which makes the detection of small mycotoxin molecules (with typical molecular weight in hundreds of daltons) a difficult task. Existing high-tech detection methods such as HPLC and mass spectroscopy can provide the required sensitivity, but such methods are expensive and time-consuming. There is a great demand for development of biosensors for toxin detection. Sensitive optical immunosensors are leading in this development [3]
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