Abstract

Simple and cost effective electrochemical technique is used to identify the single or multiple mutated genes by observing change in the transducer current (or resistance) following the target DNA hybridization on the pre-immobilized probe sequence. However, the technology has lots of shortcomings, especially poor selectivity, sensitivity and reproducible effect which hampering the practical implementation. Here, we proposed two different strategies for improving these properties. The first strategy involves the construction of multi component multi component comprising thiolated capture probe DNA and two different thiol molecules for surface dilution. This allows the simultaneous orientation control of the single stranded DNA and surface passivation to enhance the hybridization efficiency, selectivity and sensitivity. This has been demonstrated to detect food pathogen Escherichia Coli and tumor marker Cytokertain 20 by electrochemical label free DNA sensing on gold transducers. In the second strategy, we used lipid-gold nano particle composite tethered the thiol monolayers for the signal amplification and selectivity without using any fluorescent or enzyme labels for signal amplification. Both the methods are highly reproducible and reliable than the reported methods for label free DNA sensing.