Ultrasensitive Detection of HIV DNA Using an Electrochemical Biosensor with Branched DNA Amplification

This paper presents a novel strategy for ultrasensitive detection of human immunodeficiency virus (HIV) DNA by an electrochemical biosensor. By the shearing cycle of the target DNA (T-DNA), a large amount of complimentary sequence probes (CS probe DNA) are obtained. Then, the Zr4+ functional probe DNA containing many branched DNAs is captured. Next, the initiator α-bromophenylacetic acid is connected to the branched chains of probe DNA by esterification reaction. Numerous electroactive monomers, namely, ferrocene methanol isobutene esters (FMMA), are produced at the end of the branched chains by electrochemically mediated atomic transfer radical polymerization reaction. The signal of FMMA is greatly enhanced due to a large number of branched chain-loaded probe clusters containing numerous FMMA. T-DNA can be detected with a linear range of 0.1 fM–10 nM with a detection limit of 0.037 fM. The sensor is highly sensitive and selective. It has been applied to the detection of HIV DNA in human serum samples, and it has potential application prospects in the early clinical diagnosis of AIDS.