The abuse and residues of antibiotics have a great impact on the environment and organisms, and their determination has become very important. Due to their low contents, varieties and complex matrices, effective recognition, separation and enrichment are usually required prior to determination. Molecularly imprinted polymers (MIPs), a kind of highly selective polymer prepared via molecular imprinting technology (MIT), are used widely in the analytical detection of antibiotics, as adsorbents of solid-phase extraction (SPE) and as recognition elements of sensors. Herein, recent advances in MIPs for antibiotic residue analysis are reviewed. Firstly, several new preparation techniques of MIPs for detecting antibiotics are briefly introduced, including surface imprinting, nanoimprinting, living/controlled radical polymerization, and multi-template imprinting, multi-functional monomer imprinting and dummy template imprinting. Secondly, several SPE modes based on MIPs are summarized, namely packed SPE, magnetic SPE, dispersive SPE, matrix solid-phase dispersive extraction, solid-phase microextraction, stir-bar sorptive extraction and pipette-tip SPE. Thirdly, the basic principles of MIP-based sensors and three sensing modes, including electrochemical sensing, optical sensing and mass sensing, are also outlined. Fourthly, the research progress on molecularly imprinted SPEs (MISPEs) and MIP-based electrochemical/optical/mass sensors for the detection of various antibiotic residues in environmental and food samples since 2018 are comprehensively reviewed, including sulfonamides, quinolones, β-lactams and so on. Finally, the preparation and application prospects of MIPs for detecting antibiotics are outlined.

Multiple emissions of blue, green and red from a molecular imprinting sensor rationally constructed, were used for the fluorescence colorimetric visualization of a fluorescent analyte of folic acid, using a flexible post-imprinting mixing strategy. That is, two kinds of folic acid-templated molecularly imprinted polymers (MIPs) were firstly synthesized by encapsulating green and red fluorescent quantum dots (g-QDs and r-QDs) individually on SiO₂ cores, and they were then mixed at an appropriate ratio, resulting in a triple emission MIPs sensor. Upon folic acid recognition, the inherent blue fluorescence of folic acid was intensified, and the green and red fluorescence of the sensor QDs were gradually quenched. The quenching rate difference between g-QDs and r-QDs was greatly enhanced and used to obtain a wider-range and profuse fluorescence color evolution, by investigating the influences of the QDs modifier, eluent and imprinting layer thickness in detail. Under optimal conditions, the ratiometric intensity change of the three color emissions varied in a logistic function within 0.01–50 ppm of folic acid, and the corresponding fluorescence colors shifted from yellow to orange to red to purple and finally to blue. This excellent visualization capability of the MIPs sensor contributed to the accurate naked-eye detection of folic acid concentration using a portable ultraviolet lamp. Moreover, the MIPs sensor succeeded in determining folic acid in complicated food and serum samples, providing comparable results with the PRC standard method and satisfactory recoveries of 99.5–108.0%. The merits, including construction simplicity, high sensitivity and selectivity, and result visualization, enable such a multiple emission MIPs sensing strategy to be potentially applicable for visual identification and determination of various analytes in more fields.