Molecularly Imprinted Polymers Based Optical Fiber Sensors: A Review

Bio(sensors) based on molecularly imprinted polymers and silica materials used for food safety and biomedical analysis: Recent trends and future prospects

In recent decades, analytical techniques have increasingly focused on the precise quantification. Achieving this goal has been accomplished with conventional analytical approaches that typically require extensive pretreatment methods, significant reagent usage, and expensive instruments. The need for rapid, simple, and highly selective identification platforms has become increasingly pronounced. Molecularly imprinted polymer (MIP) has emerged as a promising avenue for developing advanced sensors that can potentially surpass the limitations of conventional detection methods. In recent years, the application of MIP-silica materials-based sensors has garnered significant attention owing to their distinctive characteristics. These types of probes hold a distinct advantage in their remarkable stability and durability, all of which provide a suitable sensing platform in severe environments. Moreover, the substrate composed of silica materials offers a vast surface area for binding, thereby facilitating the efficient detection of even minuscule concentrations of targets. As a result, sensors based on MIP-silica materials have the potential to be widely applied in various industries, including medical diagnosis, and food safety. In the present review, we have conducted an in-depth analysis of the latest research developments in the field of MIPs-silica materials based sensors, with a focus on succinctly summarizing and elucidating the most crucial findings. This is the first comprehensive review of integration MIPs with silica materials in electrochemical (EC) and optical probes for biomedical analysis and food safety.

A novel fluorescent probe based imprinted polymer-coated magnetite for the detection of imatinib leukemia anti-cancer drug traces in human plasma samples

Myeloid leukemia is a chronic cancer, which associated with abnormal BCR-ABL tyrosine kinase activity. Imatinib (IMB) acts as a tyrosine kinase inhibitor and averts tumor growth in cancer cells by controlling cell division, so it is urgent to develop an effective assay to detect and monitor its IMB concentration. Therefore, an innovative fluorescent biomimetic sensor is a promising sensing material that constructed for the efficient recognition of IMB and displays excellent selectivity and sensitivity stemming from molecularly imprinted polymer@Fe3O4 (MIP@Fe3O4). The detection strategy depends on the recognition of IMB molecules at the imprinted sites in the presence of coexisting molecules, which are then transferred to the fluorescence signal. The synthesized MIP@Fe3O4 was characterized using Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Furthermore, computational studies of the band gap (EHOMO-ELUMO) of the monomers, IMB, and their complexes were performed. These results confirmed that the copolymer is the most appropriate and has high stability (Binding energy; 0.004 x 10-19 KJ) and low reactivity. A comprehensive linear response over IMB concentrations from 5 × 10-6 mol/L to 8 × 10-4 mol/L with a low detection limit of 9.3 × 10-7 mol/L was achieved. Furthermore, the proposed technique displayed long-term stability (over 2 months), high intermediate precision (RSD<2.1 %), good reproducibility (RSD <1.9 %), and outstanding selectivity toward IMB over analogous molecules with similar chemical and spatial structure (no interference by 100 to 150-fold of the competitors). Owing to these merits, the proposed fluorescence sensor was utilized to detect IMB in drug tablets and human plasma, and satisfactory results (99.3-100.4 %) were obtained. Thus, the synthesized fluorescence sensor is a promising platform for IMB sensing in various applications.

Reagent-Free Lactate Detection Using Prussian Blue and Electropolymerized-Molecularly Imprinted Polymers-Based Electrochemical Biosensors

Sweat lactate, a promising biomarker for assessing physical performance and health conditions, calls for noninvasive, convenient, and affordable detection methods. This study leverages molecularly imprinted polymers (MIPs) as a synthetic biorecognition element for lactate detection due to their affordability and high stability. Traditional MIPs-based electrochemical sensors often require external redox probes such as ferricyanide/ferrocyanide in the solution to signal the binding between analytes and MIPs, which restricts their applicability. To address this, our study introduces an innovative approach utilizing a layer of Prussian blue (PB) nanoparticles as the internal redox probe on screen-printed carbon electrodes (SPCE), followed by a layer of electropolymerized MIP (eMIP) for molecular recognition, enabling reagent-free lactate detection. The real-time growth of eMIP and the processes of template elution and lactate rebinding were examined and validated using electrochemical surface plasmon resonance (EC-SPR) spectroscopy. The sensor's performance was thoroughly investigated using Differential Pulsed Voltammetry (DPV) and Electrochemical Impedance Spectroscopy (EIS) with samples spiked in 0.1 M KCl solution and artificial sweat. The developed sensors demonstrated a fast and selective response to lactate, detecting concentrations from 1 to 35 mM with a Limit of Detection (LOD) of 0.20 mM, defined by a signal-to-noise ratio of 3 in the DPV measurements. They also exhibited excellent reproducibility, reusability, and a shelf life of up to 10 months under ambient conditions. These eMIP/PB/SPCE-based lactate sensors show considerable potential as point-of-care (POC) devices for sweat lactate detection, and the technology could be adapted for reagent-free detection of a broad spectrum of molecules.

Selective adsorption of zearalenone by a novel magnetic molecularly imprinted carbon nanomaterial

In this paper, the objective is to immobilize molecularly imprinted polymers (MIPs) onto the surface of magnetic carbon nanoparticles (Fe3O4@SiO2@C) to develop an effective method for the adsorption of zearalenone (ZEN). The prepared products were characterized by FT-IR, SEM, TEM, XRD, VSM, TGA, and BET. The content of zearalenone in corn samples was monitored by HPLC. The results indicate that the particle size of magnetic molecularly imprinted polymers (MMIPs) is approximately 200 nm. The adsorption mechanism of MMIPs was confirmed by static adsorption and dynamic adsorption experiments. The maximum adsorption capacity was 1.56 mg/g, and the adsorption equilibrium was reached within 50 min. The scatchard model showed that MMIPs had two binding sites, a high-affinity binding site and a low-affinity site. Kinetic second-order fitting indicates that MMIPs are mainly through chemisorption. In the actual sample application, the limit of detection (LOD) and limit of quantitation (LOQ) were 0.3 mg/L and 0.9 mg/L, respectively. The recovery of corn with the standard addition of ZEN was 73.6-88.1%, and the relative standard deviation (RSD) was 2.86-5.63%. The results demonstrated that MMIPs possess the advantages of straightforward operation, high precision, and cost-effectiveness, rendering them suitable for rapid ZEN detection.

Recent Advances of Biosensors for Detection of Multiple Antibiotics

The abuse of antibiotics has caused a serious threat to human life and health. It is urgent to develop sensors that can detect multiple antibiotics quickly and efficiently. Biosensors are widely used in the field of antibiotic detection because of their high specificity. Advanced artificial intelligence/machine learning algorithms have allowed for remarkable achievements in image analysis and face recognition, but have not yet been widely used in the field of biosensors. Herein, this paper reviews the biosensors that have been widely used in the simultaneous detection of multiple antibiotics based on different detection mechanisms and biorecognition elements in recent years, and compares and analyzes their characteristics and specific applications. In particular, this review summarizes some AI/ML algorithms with excellent performance in the field of antibiotic detection, and which provide a platform for the intelligence of sensors and terminal apps portability. Furthermore, this review gives a short review of biosensors for the detection of multiple antibiotics.

Preparation of Molecularly Imprinted Cysteine Modified Zinc Sulfide Quantum Dots Based Sensor for Rapid Detection of Dopamine Hydrochloride

By combining surface molecular imprinting technology with cysteine-modified ZnS quantum dots, an elegant, molecularly imprinted cysteine-modified Mn²⁺: ZnS QDs (MIP@ZnS QDs) based fluorescence sensor was successfully developed. The constructed fluorescence sensor is based on a molecularly imprinted polymer (MIP) coated on the surface cysteine-modified ZnS quantum dots and used for rapid fluorescence detection of dopamine hydrochloride. The MIP@ZnS quantum dots possess the advantages of rapid response, high sensitivity, and selectivity for the detection of dopamine hydrochloride molecules. Experimental results show that the adsorption equilibrium time of MIP@ZnS QDs for dopamine hydrochloride molecules is 12 min, and it can selectively capture and bind dopamine in the sample with an imprinting factor of 29.5. The fluorescence quenching of MIP@ZnS QDs has a good linear (R² = 0.9936) with the concentration of dopamine hydrochloride ranged from 0.01 to 1.0 μM, and the limit of detection is 3.6 nM. In addition, The MIP@ZnS QDs demonstrate good recyclability and stability and are successfully employed for detection of dopamine hydrochloride in urine samples with recoveries was 95.2% to 103.8%. The proposed MIP@ZnS QDs based fluorescent sensor provides a promising approach for food safety detection and drug analysis.

Potentiometric sensor based on a computationally designed molecularly imprinted receptor

Molecularly imprinted polymer (MIP)-based polymeric membrane potentiometric sensors are ideal candidates for detection of organic species. The development of such sensors has opened new attractive horizons for potentiometric sensing. However, it should be noted that in the preparation of these MIP receptors, the selection of the functional monomer usually depends on empirical trial- and error-based optimization, which involves tedious and time-consuming experiments. In this work, the computer-aided design and synthesis of an MIP receptor are applied in the fabrication of an MIP-based potentiometric sensor. The density functional theory calculation with the B3LYP model and 6-31G(d) basis set is used to study the interactions between the functional monomer and template molecules. The binding energies of the complexations between the template molecule and different functional monomers are used as a criterion for the selection of the proper monomer. The designed MIP is then synthesized and employed as the receptor for the fabrication of the potentiometric sensor. As a proof-of-concept experiment, the antibiotic sulfadiazine has been selected as a model and 4 functional monomers, 2-hydroxyethyl methacrylate, methyl methacrylate, N-isopropylacrylamide and N-phenylacrylamide, have been chosen. The designed MIP-based sensor exhibits excellent sensitivity with a linear range of 1-10 μM and also shows a good selectivity. We believe that the proposed computer-aided synthesis technique for the MIP receptor selection can provide a general and facile way to replace the traditional empirical MIP preparation method in the fabrication of MIP-based electrochemical and optical sensors.

Recent Advances in Molecularly Imprinted Polymers for Antibiotic Analysis

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.

Effect of Surfactants on the Binding Properties of a Molecularly Imprinted Polymer

In molecularly imprinted polymers, non-specific interactions are generally based on weak forces between the polymer surface and the sample matrix. Thus, additives able to interfere with such interactions should be able to significantly reduce any non-specific binding effect. Surfactants represent an interesting class of substances as they are cheap and easily available. Here, we present a study of the effect of three surfactants (the anionic sodium dodecylsulphate, SDS, the cationic cetyltrimethylammonium bromide (CTAB) and the non-ionic polyoxyethylene-(20)-sorbitan monolaurate Tween 20) on the binding affinity of a 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)-imprinted polymer for the template and its analogue 2,4-dichlorophenoxyacetic acid (2,4-D). The experimental results indicate that increasing amounts of surfactant decrease the binding affinity for the ligands strongly for the ionic ones, and more weakly for the non-ionic one. This effect is general, as it occurs for both 2,4,5-T and 2,4-D and for both the imprinted and the not-imprinted polymers. It also proves that the magnitude of this effect mainly depends on the presence or absence of an ionic charge, and that the hydrophobic "tail" of surfactants plays only a minor role.

Preparation and Application of Molecularly Imprinted Polymers for Flavonoids: Review and Perspective

The separation and detection of flavonoids from various natural products have attracted increasing attention in the field of natural product research and development. Depending on the high specificity of molecularly imprinted polymers (MIPs), MIPs are proposed as efficient adsorbents for the selective extraction and separation of flavonoids from complex samples. At present, a comprehensive review article to summarize the separation and purification of flavonoids using molecular imprinting, and the employment of MIP-based sensors for the detection of flavonoids is still lacking. Here, we reviewed the general preparation methods of MIPs towards flavonoids, including bulk polymerization, precipitation polymerization, surface imprinting and emulsion polymerization. Additionally, a variety of applications of MIPs towards flavonoids are summarized, such as the different forms of MIP-based solid phase extraction (SPE) for the separation of flavonoids, and the MIP-based sensors for the detection of flavonoids. Finally, we discussed the advantages and disadvantages of the current synthetic methods for preparing MIPs of flavonoids and prospected the approaches for detecting flavonoids in the future. The purpose of this review is to provide helpful suggestions for the novel preparation methods of MIPs for the extraction of flavonoids and emerging applications of MIPs for the detection of flavonoids from natural products and biological samples.

Determination of total cathinones with a single molecularly imprinted fluorescent sensor assisted by electromembrane microextraction

An electromembrane microextraction (EME)-assisted fluorescent molecularly imprinted polymer (MIP) sensing method is presented for detecting the total cathinone drugs in urine samples. In this detection system, the clean-up ability of EME eliminated the matrix effects on both target binding with MIPs and the luminescence of the fluorophore in the sensor. Moreover, by optimizing the extraction conditions of EME, different cathinone drugs with a same concentration show a same response on the single aggregation induced emission (AIE) based MIP (AIE-MIP) sensor (λ_ex = 360 nm, λ_em = 467 nm). The recoveries were 57.9% for cathinone (CAT) and 78.2% for methcathinone (MCAT). The EME-assisted "light-up" AIE-MIP sensing method displayed excellent performance with a linear range of 2.0-12.0 μmol L^-1 and a linear determination coefficient (R²) of 0.99. The limit of detection (LOD) value for EME-assisted "light-up" AIE-MIP sensing method was 0.3 μmol L^-1. The relative standard deviation (RSD) values for the detection were found to be within the range 2.0-12.0%. To the best of our knowledge, this is the first time that determination of total illicit drugs with a single fluorescent MIP sensor was achieved and also the first utilization of sample preparation to tune the sensing signal of the sensor to be reported. We believe that this versatile combination of fluorescent MIP sensor and sample preparation can be used as a common protocol for sensing the total amount of a group of analytes in various fields.

Paper-Based Molecular-Imprinting Technology and Its Application

Paper-based analytical devices (PADs) are highly effective tools due to their low cost, portability, low reagent accumulation, and ease of use. Molecularly imprinted polymers (MIP) are also extensively used as biomimetic receptors and specific adsorption materials for capturing target analytes in various complex matrices due to their excellent recognition ability and structural stability. The integration of MIP and PADs (MIP-PADs) realizes the rapid, convenient, and low-cost application of molecular-imprinting analysis technology. This review introduces the characteristics of MIP-PAD technology and discusses its application in the fields of on-site environmental analysis, food-safety monitoring, point-of-care detection, biomarker detection, and exposure assessment. The problems and future development of MIP-PAD technology in practical application are also prospected.

Molecularly imprinted polymers for selective extraction/microextraction of cancer biomarkers: A review

Over recent years, great efforts have been extensively documented in top scientific journals on the development of methods for early diagnosis, treatment, and monitoring of cancers which are prevalent critical diseases with a high mortality rate among men and women. The determination of cancer biomarkers using different optimum methodologies is one of the finest options for achieving these goals with more precision, speed, and at a lower cost than traditional clinical procedures. In this regard, while focusing on specific biomarkers, molecularly imprinted technology has enabled novel diagnostic techniques for a variety of diseases. Due to the well-known advantages of molecularly imprinted polymers (MIPs), this review focuses on the current trends of MIPs-based extraction/microextraction methods, specifically targeting cancer biomarkers from various matrices. These optimized methods have demonstrated high selectivity, accuracy, sorbent reusability, extraction recovery, and low limits of detection and quantification for a variety of cancer biomarkers, which are a powerful tool to provide early diagnosis, prognosis, and treatment monitoring, with potential clinical application expected soon. This review highlights the key progress, specific modifications, and strategies used for MIP synthesis. The future perspectives for cancer biomarkers purification and determination by fabricating MIP-based techniques are also discussed.