Abstract
A highly sensitive sandwich DNA detection method based on voltammetric detection of thionine-capped gold nanoparticle (AuNP)/reporter DNA conjugate tags on gold particle-modified screen-printed carbon electrode (SPCE) was developed. The SPCE was modified with gold particle by electrodeposition of gold on SPCE surface. The DNA sensor was prepared by self-assembly of a thiolated DNA probe on gold particle-modified SPCEs. The sandwich-type system was formed by specific recognition of biosensor surface-confined probe DNA to target DNA, followed by attachment of thionine-capped AuNPs/reporter DNA conjugates. The biosensor is very sensitive because of the large number of electroactive thionine molecules in the thionine-capped AuNPs/reporter DNA conjugates. Under optimal conditions, the dynamic detection range of target DNA was from 1.0 × 10−16 to 1.0 × 10−14 mol L−1, and the detection limit was 0.5 × 10−16 mol L−1. The DNA sensor exhibited selectivity against single-base mismatched DNA.
Highlights
High-sensitivity detection of nucleic acids is essential in clinical diagnosis, pathology, and genetics [1, 2]
We report the preparation of thionine-capped AuNP/reporter DNA conjugates and their application in sandwich-type electrochemical detection of target DNA at low levels
The thioninecapped AuNP/reporter DNA conjugate solution was coated onto the resultant electrode surface, and the interaction was kept at room temperature for 30 min to obtain a sandwich sensing system
Summary
High-sensitivity detection of nucleic acids is essential in clinical diagnosis, pathology, and genetics [1, 2]. AuNPs have been employed to amplify signals by forming a nanoparticle ensemble substrate on electrode, thereby increasing the amount of immobilized probe DNA on the electrode surface [11]. We report the preparation of thionine-capped AuNP/reporter DNA conjugates and their application in sandwich-type electrochemical detection of target DNA at low levels. The sandwich-type system is formed by specific recognition of biosensor surface-confined probe DNA to target DNA, followed by successive attachment of thioninecapped AuNPs/reporter DNA conjugates.
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