Aptamer-target complex

It is not surprising that wide range of aptamer-based sensors (aptasensors) have been reported in the literature.118-120 Recently, electrochemical aptamer sensors gained considerable attention.121,122 Since, nucleic acids aptamers fold their structure upon binding to the target molecule, formation of the aptamer-target complex can be... 

Target presentation 2 (immobilization of aptamer-target complex on nitrocellulose filter)... 

Electronic aptasensors reveal certain advantages when compared to optical aptasensors (1) The possibility of coupling amplifying catalytic or biocatalytic labels to an aptamer-target complex enables amplified detection of the target substrate and thus enhancing the sensitivity of sensing processes and (2) recent advances demonstrated the electronic label-free detection of the substrate by the aptamers, and thus the elimination of fluorescent labels may be excluded. 

A very simple and sensitive method has recently been published based on direct amplification of an aptamer specific for the reverse transcriptase of the human immunodeficiency virus type 1 (HlV-1 RTase) (Zhang et ah, 2006). After incubation of the protein with the aptamer, the complex formed is separated from the unbound aptamer by capillary electrophoresis. After collection of the aptamer-target complex, the aptamer was dissociated from the target and directly amplified by PCR. Approximately 10 molecules of target were detected using this method, improving the sensitivity of protein detection by several orders of magnitude. 

The designing of advanced aptamer-based diagnostics and therapeutics requires aptamers with predefined kinetic and/or thermodynamic parameters of aptamer-target interaction. Technological limitations of aptamer selection methods have so far precluded selection of such aptamers. Two KCE methods, ECEEM and NECEEM,have been successfully used for the selection of aptamers with predefined Kd and kos of aptamer-target complexes. Conceptually, in ECEEM,... 

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