Question

how does the aptamer immobilization process occur during Ochratoxin A detection using aptasensor or any other type of biosensor.

what is the immobilization method used for the detection of OTA in dry wheat using a fluorescence-based array biosensor with Biotinylated aptamer as a biorecognition element. how does the process of immobilization occur in this case?

Answer 1

Generally, the most preferred approach to immobilise ligands is through chemistries that lead to covalent bonding with minimal non-specific adsorption. Although covalent chemistries are quite challenging to achieve, they are robust, economical in the long term and can be used multiple times.

Aptamers are short (35-100 nucleotides) single-stranded DNA (ssDNA) or RNA oligonucleotides with highest binding affinity toward targets due to their 3D conformations.Aptamers are oligonucleotides that are able to form three-dimensional structures through Van der Waals interactions or electrostatic interactions and that can bind to a variety of targets. Aptamers were successfully used for detecting other relevant molecules, such as β-conglutin and IgE and small molecules such as ochratoxin A, cocaine, and adenosine triphosphate (ATP).

In comparison with Abs, Aps show high physicochemical stability and specificity, reasonable cost-effectiveness, longer shelf-life, simplicity in modification, and relatively high persistence to denaturation

the identification of an aptamer that binds with high affinity and specificity to ochratoxin A (OTA), a mycotoxin that occurs in wheat and other foodstuffs, and a quantitative detection method for OTA based on the use of this aptamer. Aptamers are single-stranded oligonucleotides selected in vitro to bind to molecular targets. The aptamer selected in this work exhibited a dissociation constant in the nanomolar range and did not bind compounds with structures similar to OTA such as N-acetylphenylalanine or warfarin. The aptamer bound with a 100-fold less affinity to ochratoxin B. The selected aptamers could be used for the determination of ppb quantities of OTA in naturally contaminated wheat samples. Further work is ongoing to broaden the application demonstrated here with the development of sensors, affinity columns, and other analytical systems for field and laboratory determination of this toxin in food and agricultural products.