Fluorine-nitrogen co-doped carbon dots with stable and strong electrochemiluminescence as an emitter for ultrasensitive detection of HIV-DNA fragment

Herein, the fluorine-nitrogen co-doped carbon dots (FNCDs) with stable and strong electrochemiluminescence (ECL) was used as a novel ECL emitter for constructing an ultrasensitive biosensor to detect human immunodeficiency virus (HIV) DNA fragment. The doping of fluorine and nitrogen in the carbon dots (CDs) not only effectively formed hydrogen bonds to hinder the free rotation of CDs for increasing the radiation transition probability, but also changed the charge distribution of CDs leading to a narrower energy gap, which improved the ECL intensity and stability of FNCDs. Moreover, exonuclease III (Exo III) -assisted multiple recycling amplification could convert the trace HIV-DNA fragment into a large amount of output DNA to trigger horizontal hybridization chain reaction (H-HCR) to form Y-supported three-dimensional (3D) network DNA nanostructure for immobilizing a lot of doxorubicin-ferrocenecarboxylic acid (Dox-FcCOOH) as ECL quencher, which significantly improved the sensitivity of the proposed biosensor. Thus, the fabricated ECL biosensor realized ultrasensitive detection of HIV-DNA fragment in the concentration range of 10 aM to 10 pM with a detection limit as low as 6.34 aM. This strategy provided a novel ECL emitter to construct biosensors for detection of biomolecule and early clinical disease diagnosis.