Novel single-stranded DNA binding protein-assisted fluorescence aptamer switch based on FRET for homogeneous detection of antibiotics

Herein, a smart single-stranded DNA binding protein (SSB)-assisted fluorescence aptamer switch based on fluorescence resonance energy transfer (FRET) was designed. The FRET switch was synthesized by connecting SSB labeled quantum dots ([email protected]) as donor with aptamer (apt) labeled gold nanoparticles ([email protected]) as acceptor, and it was employed for detecting chloramphenicol (CAP) in a homogenous solution. In the assay, the interaction between core-shell [email protected] and [email protected] leads to a dramatic quenching (turning off). After adding CAP in the detection system, [email protected] can bind the target specifically then separate [email protected] with [email protected], resulting in restoring the fluorescence intensity of QDs (turning on). Consequently, the fluorescence intensity recovers and the recovery extent can be used for detection of CAP in homogenous phase via optical responses. Under optimal conditions, the fluorescence intensity increased linearly with increasing concentrations of CAP from 0.005 to 100 ng mL−1. The limit of this fluorescence aptamer switch was around 3 pg mL−1 for CAP detection. When the analyte is changed, the assay can be applied to detect other targets only by changing relative aptamer in [email protected] probe. Furthermore, it has potential to be served as a simple, sensitive and portable platform for antibiotic contaminants detection in biological and environmental samples.