Beta-cyclodextrin-functionalized CdS nanorods as building modules for ultrasensitive photoelectrochemical bioassay of HIV DNA.

Nowadays, acquired immunodeficiency syndrome has become a formidable danger to human health, and its early diagnosis is urgent need with the increasing quantity of patients around the world. Herein, we first synthesized beta-cyclodextrin-functionalized CdS nanorods (β-CD@CdS NRs) with high stability and desirable photo-electricity activity, and served as easy-to-assemble building modules to design a novel photoelectrochemical biosensor for human immune deficiency virus (HIV) DNA detection by coupling with catalytic hairpin assembly (CHA)-mediated biocatalytic precipitation and the host-guest interaction between adamantine (ADA) and β-CD. In the presence of HIV DNA, CHA process was triggered with the aid of hairpin DNA1 and ADA-labelled hairpin DNA2, and then generated large amounts of G-quadruplex, which could be formed hemin/G-quadruplex DNAzyme to catalyze 4-chloro-1-naphthol to generate insoluble precipitation on photoelectrode surface, followed by the decreased photocurrent response due to the corresponding stereo-hindrance effect. Under optimized conditions, this biosensor exhibited wide linear dynamic range (10 fM - 1 nM) and low detection limit of 1.16 fM, as well as high sensitivity, excellent stability, and satisfactory feasibility in human-serum samples. Moreover, the prepared β-CD@CdS NRs could be applied to the construction of other advanced sensing platform, showing great prospect in clinical diagnostics.