Aptamers are single strand oligonucleotides, either DNA or RNA, sequences. These sequences are selected from very large number of random sequences by an in vitro iterative process, known as SELEX, to bind to the target molecules.  Aptamers for metal ions, small organic molecules, proteins as well as whole cells were reported in the literature. It was shown that the binding affinity of aptamers to its target protein is equal and greater than the corresponding antibodies. Hence, currently there has been a great interest to use these artificial antibodies as an affinity reagent in biosensor for protein detection. Earlier we reported a procedure to optimize the immobilization of aptamer on sensor surface, via self-assembly, to increase the specific binding to its target protein, thrombin, and minimize the non-specific adsorption of other proteins. In this presentation we report a procedure, known as proximity immobilization, to imprint two aptamers, which binds at two different binding sites on the thrombin, on the gold surface via self-assembly. This gold surface was used as a surface plasmon resonance sensor surface to detect the protein binding. The resulting biosensor detects protein in the very low concentration range than it is possible to detect using any one of the aptamer biosensor alone.

Proximity immobilization of DNA aptamers for protein detection using surface plasmon resonance

245th National Meeting (2013)

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