Novel hybrid probe based on double recognition of aptamer-molecularly imprinted polymer grafted on upconversion nanoparticles for enrofloxacin sensing.

A novel luminescent "double recognition" method for the detection of enrofloxacin (ENR) is developed to overcome some of the challenges faced by conventional molecularly imprinting. Biotinylated ENR aptamers immobilised on upconversion nanoparticles (UCNPs) surface are implemented to capture and concentrate ENR as the first imprinting recognition safeguard. After correct folding of the aptamer upon the existing targets, polymerization of methacrylic acid monomers around the ENR-aptamer complexes to interact with the residual functional groups of ENR by using molecularly imprinting techniques is the second imprinting recognition safeguard. The "double recognition" imprinting cavities are formed after removal of ENR, displaying recognition properties superior to that of aptamer or traditional molecularly imprinting alone. Another interest of this method is simultaneous molecular recognition and signal conversion by fabricating the "double recognition" receptor on to the surface of UCNPs to form a hybrid sensing system of apta-MIP/UCNPs. The proposed sensing method is applied to measure ENR in different fish samples. Good recoveries between 87.05% and 96.24%, and relative standard deviation (RSD) values in the range of 1.19-4.83% are obtained, with the limits of detection and quantification of 0.04 and 0.12ng/mL, respectively. It indicates that the sensing method is feasible for the quantification of target ENRs in real samples, and show great potential for wide-ranging application in bioassays.