Carbon dots-based fluorescence resonance energy transfer for the prostate specific antigen (PSA) with high sensitivity.

The accurate and sensitive detection of biomarkers has great clinical value for the early diagnosis and treatment of cancer. Due to the excellent optical properties of carbon dots (CDs), CDs-based fluorescent detection methods have attracted increasing attention in bioanalytics. Signal reporters using CDs labeled hairpin DNA, based on Föster resonance energy transfer (FRET), have shown promise for the sensitive detection of biomarkers. In this work, a new method for sensitive biomarker detection using an enzyme-free amplified fluorescence strategy was developed. The strategy was based on FRET between CDs and graphene oxide (GO) combined with catalytic hairpin assembly (CHA). In the absence of the target, the CD-labeled hairpin DNA adsorb onto GO via hydrophobic and π-π stacking interactions, resulting in a FRET quenching of the CDs fluorescence. The introduction of the target could trigger the CHA circuits to form Y-shaped double-stranded DNA (dsDNA), resulting in a recovery of the CD's fluorescence signal. This novel strategy was successfully applied for the selective detection of prostate specific antigen (PSA) with a limit of detection (LOD) of 0.22 ng mL (3σ/k). Additionally, the method could be used to detect carcinoembryonic antigen (CEA) and adenosine triphosphate (ATP) with LOD of 0.56 ng mL (3σ/k) and 80 nM (3σ/k), respectively. Therefore, this work demonstrates a promising way to construct a sensitive and versatile detection platform.