Abstract
This work reports on further development of an optical biosensor for the in vitro detection of mycotoxins (in particular, aflatoxin B1) using a highly sensitive planar waveguide transducer in combination with a highly specific aptamer bioreceptor. This sensor is built on a SiO2–Si3N4–SiO2 optical planar waveguide (OPW) operating as a polarization interferometer (PI), which detects a phase shift between p- and s-components of polarized light propagating through the waveguide caused by the molecular adsorption. The refractive index sensitivity (RIS) of the recently upgraded PI experimental setup has been improved and reached values of around 9600 rad per refractive index unity (RIU), the highest RIS values reported, which enables the detection of low molecular weight analytes such as mycotoxins in very low concentrations. The biosensing tests yielded remarkable results for the detection of aflatoxin B1 in a wide range of concentrations from 1 pg/mL to 1 μg/mL in direct assay with specific DNA-based aptamers.Graphical abstractOptical planar waveguide polarization interferometry biosensor for detection of aflatoxin B1 using specific aptamer.
Highlights
This work is dedicated to development of novel optical biosensing technologies for detection of low molecular weight analytes such as toxins
We explore the use of aptamers as specific bioreceptors for in vitro detection of aflatoxin B1 in a combination with a highly sensitive polarization interferometer (PI) optical planar waveguide (OPW) method
The main aim of developing the experimental setup for polarization interferometry biosensor based on optical planar waveguide suitable for in vitro detection of mycotoxins was achieved
Summary
This work is dedicated to development of novel optical biosensing technologies for detection of low molecular weight analytes such as toxins. A logical continuation of this direction in biosensor development was the use of optical planar waveguide (OPW) operating as a polarization interferometer (PI) with the multiperiodic output signal proportional to the phase shift between p- and scomponents of polarized light [8] Previous attempts in this development were encouraging [9, 10]; the PI OPW devices demonstrated high refractive index sensitivity (RIS) which allows the detection of mycotoxins (aflatoxin B1, ochratoxin A, and zearalenone) in concentrations down to 0.01 ppb. The signal recordings, which were performed during washing out non- bound toxin molecules after each binding stage, typically yield 2.36 ± 0.14 rad of phase change (see Fig. 5a, red columns) The fact that this value is practically independent on the AFT B1 concentration indicates that non-specific adsorption most likely takes place in voids between immobilized aptamers. The repeating of a thermo-cycle is advisable before the use
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