A ratiometric fluorescence biosensor based on enzyme-cascade signal amplification technology for the detection of lincomycin

An enzyme-nanozyme cascade amplified ratio fluorescence (RF) biosensor based on prepared MnFe-layered double hydroxide nanosheets (Mn-Fe LDH) and alkaline phosphatase (ALP) has been developed for sensitive and accurate detection of lincomycin (LIN). In this strategy, Mn-Fe LDH can catalyze the o-phenylenediamine (OPD) oxidation to generate fluorescence 2, 3-diaminophenazine (DAP) with a fluorescence wavelength of 565 nm. This study utilized LIN aptamer-modified magnetic beads and alkaline phosphatase-labeled complementary strand hybridization to prepare the MBs-Apt@cDNA-ALP. The MBs-Apt@cDNA-ALP could recognize LIN and release cDNA-ALP from the surface of the magnetic beads. After magnetic separation, cDNA-ALP catalyzed the 2-phosphate ascorbic acid (AAP) conversion to ascorbic acid (AA). The redox reaction between AA and Mn-Fe LDH led to a decrease in DAP production and fluorescence intensity . At the same time, AA converted into dehydroascorbic acid (DHAA), which reacted with OPD to form a quinoline derivative (DFQ) that emitted fluorescence at 435 nm. The constructed LIN biosensor exhibited a detection range of 1.125–250 nM with a limit of detection (LOD) of 0.0492 nM. Moreover, the RF aptasensor can eliminate background interference, deliver remarkable signal variations, and effectively analyze the LIN concentration in grass carp and shrimp samples. • A ratio fluorometric aptasensor was constructed for the detection of lincomycin . • The ratio fluorometric signal can effectively avoid false positive detection results. • The Mn-Fe LDH was cascaded with ALP for amplifying the ratio fluorometric signal. • The sensor can be used to detect lincomycin down to the detection limit of 0.0492 nM.