BACKGROUND: Fluoroquinolones (FQs) are widely used for their excellent antimicrobial properties, yet their release into aquatic environments pose risks to ecosystems and public health. The accurate monitoring and analysis of FQs present challenges due to their low concentrations and the complex matrices found in actual environmental samples. To address the need for auto-pretreatment and on-line instrumental analysis, developing new microextraction materials and protocols is crucial. Such advancements will provide better analytical assurance for the effective extraction and determination of FQs at trace levels, which is of great significance to environmental protection and human health.
RESULTS: In this work, we presented a Co2+ mediated paper-based molecularly imprinted polymer chip (CMC@Co-MIP), combined with UPLC analysis, to develop an effective analytical method for identifying and quantifying trace amounts of ciprofloxacin (CIP) and enrofloxacin (ENR) in water samples. Notably, the addition of Co2+ in CMC@Co-MIP helped to capture the template molecule CIP through coordination before imprinting, which significantly improved the ordering of the imprinted cavities. CMC@Co-MIP exhibited a maximum adsorption capacity up to 500.20 mg g-1 with an imprinting factor of 4.12, surpassing previous reports by a significant margin. Furthermore, the enrichment mechanism was extensively analyzed by various characterization techniques. The developed method showed excellent repeatability and reproducibility (RSD < 13.0 %) with detection limits ranging from 0.15 to 0.21 μg L-1 and recoveries ranging from 64.9 % to 102.3 % in real spiked water samples.
CONCLUSIONS: We developed a novel microextraction paper-based chip based on Co2+ mediation, which effectively improved the selectivity and convenience of extracting FQs. This breakthrough allowed the chip to have a high enrichment efficiency as well as provide a robust on-line instrumental program. It also confirms that the imprinting scheme based on metal ion coordination is a high-performance strategy.

Molecular imprinting has emerged as an important and practical technology to create economical and stable synthetic mimics of antibodies and enzymes. It has already found a variety of important applications, such as affinity separation, chemical/biological sensing, disease diagnostics, proteomics, bioimaging, controlled drug release, and catalysis. In the past decade, significant breakthroughs have been made in non-covalently imprinted polymers, from their synthesis through to their applications. In terms of synthesis, quite a few versatile and facile imprinting approaches for preparing MIPs have been invented, which have effectively solved some key issues in molecular imprinting. Additionally, important applications in several areas, such as sensors, proteomics and bioimaging, have been well demonstrated. In this review, we critically and comprehensively survey key recent advances made in the preparation of non-covalently imprinted polymers and their important applications. We focus on the state-of-art of this technology from three different perspectives: fundamentals, synthetic strategies, and applications. We first provide a fundamental basis for molecular imprinting technologies that have been developed, which is extremely helpful for establishing a sound understanding of the challenges in molecular imprinting. Then, we discuss in particular the major breakthroughs within the last ten years (2014-2024), with emphasis on new imprinting approaches, what strengths the breakthroughs can provide, and which new applications the properties of the prepared non-covalently imprinted polymers are fit for.

A dual-emission ratiometric fluorescence sensor (CDs@CdTe@MIP) with a self-calibration function was successfully constructed for AMO detection. In the CDs@CdTe@MIP system, non-imprinted polymer-coated CDs and molecule-imprinted polymer-coated CdTe quantum dots were used as the reference signal and response elements, respectively. The added AMO quenched the fluorescence of the CdTe quantum dots, whereas the fluorescence intensity of the CDs remained almost unchanged. The AMO concentration was monitored using the fluorescence intensity ratio (log(I647/I465)0/(I647/I465)) to reduce interference from the testing environment. The sensor with a low detection limit of 0.15 μg/L enabled detection of the AMO concentration within 6 min. The ratiometric fluorescence sensor was used to detect AMO in spiked pork samples; it exhibited a high recovery efficiency and relative standard deviation (RSD) of 97.94-103.70% and 3.77-4.37%, respectively. The proposed highly sensitive and selective platform opens avenues for sensitive, reliable, and rapid determination of pharmaceuticals in the environment and food safety monitoring using ratiometric sensors.

A dual-template molecularly imprinted electrochemical sensor was developed for the simultaneous detection of serotonin (5-HT) and glutamate (Glu). First, amino-functionalized reduced graphene oxide (NRGO) was used as the modification material of a GCE to increase its electrical conductivity and specific surface area, using Glu and 5-HT as dual-template molecules and o-phenylenediamine (OPD) with self-polymerization ability as functional monomers. Through self-assembly and electropolymerization, dual-template molecularly imprinted polymers were formed on the electrode. After removing the templates, the specific recognition binding sites were exposed. The amount of NRGO, polymerization parameters, and elution parameters were further optimized to construct a dual-template molecularly imprinted electrochemical sensor, which can specifically recognize double-target molecules Glu and 5-HT. The differential pulse voltammetry (DPV) technique was used to achieve simultaneous detection of Glu and 5-HT based on their distinct electrochemical activities under specific conditions. The sensor showed a good linear relationship for Glu and 5-HT in the range 1 ~ 100 μM, and the detection limits were 0.067 μM and 0.047 μM (S/N = 3), respectively. The sensor has good reproducibility, repeatability, and selectivity. It was successfully utilized to simultaneously detect Glu and 5-HT in mouse serum, offering a more dependable foundation for objectively diagnosing and early warning of depression. Additionally, the double signal sensing strategy also provides a new approach for the simultaneous detection of both electroactive and non-electroactive substances.

Deoxynivalenol-3-glucoside (D3G), the masked form of the important mycotoxin deoxynivalenol (DON), displays potential toxicity but is difficult to control owing to the lack of rapid detection methods. Herein, an innovative molecularly imprinted polymer (MIP)-based electrochemical sensor was developed for the rapid detection of D3G. MIP, an efficient recognition element for D3G, was electropolymerized using o-phenylenediamine based on a surface functional monomer-directing strategy for the first time. CeO2, which contains both Ce3+ and Ce4+ oxidation states, was introduced as a nanozyme to catalyze H2O2 reduction, while Mn doping generated more oxygen vacancies and considerably improved the catalytic activity. Mn-CeO2 also served as a promising substrate material because of its large surface area and excellent conductivity. Under optimal conditions, a good linear relationship was observed for D3G detection over the concentration range of 0.01-50 ng/mL. The proposed sensor could detect D3G down to 0.003 ng/mL with excellent selectivity, even distinguishing its precursor DON in complex samples. The sensor exhibited acceptable stability with high reproducibility and accuracy, and could successfully determine D3G in grain samples. To the best of our knowledge, this is the first electrochemical sensing platform for rapid D3G detection that can easily be expanded to other masked mycotoxins.

Glycinamide ribonucleotide formyltransferase (GARFT) is an important enzyme in the folate metabolism pathway, and chemical drugs targeting GARFT have been used in tumor treatments over the past few decades. The development of novel antimetabolism drugs that target GARFT with improved performance and superior activity remains an attractive strategy. Herein, we proposed a targeted double-template molecularly imprinted polymer (MIP) for enhancing macrophage phagocytosis and synergistic antimetabolic therapy. The double-template MIP was prepared by imprinting the exposed peptide segment of the extracellular domain of CD47 and the active center of GARFT. Owing to the imprinted cavities on the surface of MIP, it can actively target cancer cells and mask the \"do not eat me\" signal upon binding to CD47 thereby blocking the CD47-SIRPα pathway and ultimately enhancing phagocytosis by macrophages. In addition, MIP can specifically bind to the active center of GARFT upon entry into the cells, thereby inhibiting its catalytic activity and ultimately interfering with the normal expression of DNA. A series of cell experiments demonstrated that MIP can effectively target CD47 overexpressed 4T1 cancer cells and inhibit the growth of 4T1 cells. The enhanced phagocytosis ability of macrophages-RAW264.7 cells was also clearly observed by confocal imaging experiments. In vivo experiments also showed that the MIP exhibited a satisfactory tumor inhibition effect. Therefore, this study provides a new idea for the application of molecular imprinting technology to antimetabolic therapy in conjunction with macrophage-mediated immunotherapy.

Milk, as a widely consumed nutrient-rich food, is crucial for bone health, growth, and overall nutrition. The persistent application of veterinary drugs for controlling diseases and heightening milk yield has imparted substantial repercussions on human health and environmental ecosystems. Due to the high demand, fresh consumption, complex composition of milk, and the potential adverse impacts of drug residues, advanced greener analytical methods are necessitated. Among them, functional materials-based analytical methods attract wide concerns. The magnetic molecularly imprinted polymers (MMIPs), as a kind of typical functional material, possess excellent greenification characteristics and potencies, and they are easily integrated into various detection technologies, which have offered green approaches toward analytes such as veterinary drugs in milk. Despite their increasing applications and great potential, MMIPs\' use in dairy matrices remains underexplored, especially regarding ecological sustainability. This work reviews recent advances in MMIPs\' synthesis and application as efficient sorbents for veterinary drug extraction in milk followed by chromatographic analysis. The uniqueness and effectiveness of MMIPs in real milk samples are evaluated, current limitations are addressed, and greenification opportunities are proposed. MMIPs show promise in revolutionizing green analytical procedures for veterinary drug detection, aligning with the environmental goals of modern food production systems.

Histamine is a highly toxic biogenic amine in food, making its sensitive and rapid detection methods vital for the assurance of edible safety and human health. Here, we explored for the first time a smartphone-enabled ratiometric imprinted fluorescence sensor based on blue/orange MXene quantum dots (MQDs) for fluorescence and visual detection of histamine. A linear relationship between the concentration of histamine and the fluorescence response of the sensor was found in the range of 1-60 μM with a limit of detection (LOD) of 21.9 nM for fluorescence detection and 92.2 nM for visual detection. In addition, the method was validated for the detection of real samples with excellent recoveries from 96.52% to 105.32%. Therefore, this work greatly expands the application of MQDs in the fluorescence sensing field, as well as provides a visual strategy for in-situ detection of histamine in food.

In this study, a thin poly (methyl methacrylate) coating was formed on a self-assembled monolayer formed on a gold plate after chemically binding estrone. Subsequently, the estrone molecules were hydrolyzed and extracted using a solvent to form a molecular-imprinted system. The estrone-imprinted gold plate was then used as a working electrode to measure the estrone recognition ability through electrochemical methods. The recognition ability of this working electrode was evaluated for similar compounds. The selectivity factors for the seven estrone analogs were measured, and these values ranged from 0.19 to 0.67. According to the experimental results, the estrone-imprinted system showed good differentiation of estrone from other estrone analogs. Comparing these selectivity factors with those of a previous study on a cholesterol-imprinted system, the relative molecular size difference between the target molecule and similar molecules had a significant impact on the selectivity factor.

Nanoparticles of molecularly imprinted polymers (nanoMIPs) combine the excellent recognition ability of imprinted polymers with specific properties related to the nanosize, such as a high surface-to-volume ratio, resulting in highly performing recognition elements with surface-exposed binding sites that promote the interaction with the target and, in turn, binding kinetics. Different synthetic strategies are currently available to produce nanoMIPs, with the possibility to select specific conditions in relation to the nature of monomers/templates and, importantly, to tune the nanoparticle size. The excellent sensing properties, combined with the size, tunability, and flexibility of synthetic protocols applicable to different targets, have enabled the widespread use of nanoMIPs in several applications, including sensors, imaging, and drug delivery. The present review summarizes nanoMIPs applications in sensors, specifically focusing on electrochemical detection, for which nanoMIPs have been mostly applied. After a general survey of the most widely adopted nanoMIP synthetic approaches, the integration of imprinted nanoparticles with electrochemical transducers will be discussed, representing a key step for enabling a reliable and stable sensor response. The mechanisms for electrochemical signal generation will also be compared, followed by an illustration of nanoMIP-based electrochemical sensor employment in several application fields. The high potentialities of nanoMIP-based electrochemical sensors are presented, and possible reasons that still limit their commercialization and issues to be resolved for coupling electrochemical sensing and nanoMIPs in an increasingly widespread daily-use technology are discussed.