A biosensor based on magnetic microspheres functionalized with a DNA-aptamer was developed for the specific biomonitoring of biological contaminants (mycotoxins) in urine.
The biosensor is used in a test tube into which the diluted urine sample is added. The biosensor has been validated for the monitoring of ochratoxin (OTA) with high sensitivity and selectivity thanks to the presence of a DNA sequence (aptamer), specifically designed to capture traces of the analyte (up to 10-12 ng/mL of OTA), and to a DNA-based system specifically designed to hyper-amplify the detection signal, in 4 hours, and at a constant temperature of 30 °C.
The OTA is concentrated in the sample and its presence displayed as a blue tint in the solution. It does not require special equipment other than pipettes and a small portable incubator. The biosensor can also be used for quantitative analysis using a portable photometer, with recoveries greater than 95%, high specificity and precision.
The biosensor is being validated for the analysis of other contaminants in food matrices or biological samples.
Mycotoxins are biological contaminants of food and feed commonly analysed by chromatographic techniques that require expensive and cumbersome equipment and skilled operators. The biosensor, on the other hand, represents a valid alternative thanks to its high portability and ease of use, as well as a reduction in costs and analysis times. We have shown that the results obtained with the biosensor are comparable to those obtained with the standard chromatographic methods. Another strength of the biosensor is the ability to concentrate the analyte in the sample, thereby increasing sensitivity. The biosensor does not require any purification of the urine sample, thus speeding up the analysis time. The portability of the biosensor allows its use on site, facilitating monitoring studies, and allowing the implementation of contamination containment measures in a short time. Due to the plasticity and high versatility of the biosensor structure, it can be used for the detection of other contaminants such as pesticides, viruses, drugs, etc., in a simple way, by modifying only one component of the biosensor. It differs from other diagnostic systems for its high sensitivity and applicability in complex matrices such as urine samples.