Fluorescent aptasensor for chloramphenicol detection using DIL-encapsulated liposome as nanotracer

A novel fluorescence aptasensor was successfully developed to respond to chloramphenicol (CAP) in food based on magnetic aptamer-liposome vesicle probe. In order to fabricate it, aptamer labeled on functionalized magnetic beads (MB) was firstly employed as capture adsorbent (MB-Apt), then SSB (single-stranded DNA binding protein) and DIL (1,1′-dioctadecyl-3,3,3′,3′-tetramethyl-indocarbocyanineperchlorate) coimmobilized liposomes (SSB/DIL-Lip) was employed as vesicle signal tracer. The composite vesicle probe is formed between SSB/DIL-Lip and MB-Apt based on SSB's specific recognition towards aptamer on vesicle signal tracer. Upon the vesicle probe solution reacted with CAP, the aptamer on the magnetic beads preferentially bounded with CAP, and then released SSB/DIL-Lip vesicle signal tracer in the supernatant after magnetic separation. The released tracer can emit fluorescence which was correspondence with the concentration of the analyte. At the optimum conditions, the aptasensor exhibited a good linear response for CAP detection in the range of 0.003-10 nM with a detection limit of 1 pM. Importantly, the methodology was further validated for analyzing CAP in fish samples with consistent results obtained by ELISA kit, thus providing a promising approach for quantitative monitoring of CAP and significant anti-interference ability in food safety.