Molecularly Imprinted Polymer Layer Research Articles

ZIF-12-derived nitrogen doped porous carbon nanosheets-functionalized with silver nanoparticles for ratiometric molecularly-imprinted electrochemical sensing of D-penicillamine

In this work, an electrochemical platform was developed for detection of D-pencillamine utilizing highly responsive molecularly imprinted polymers (MIPs). This platform operates on a ratiometric principle and is constructed on nitrogen-doped porous carbon nanosheets (N-PCNS) derived from zeolite imidazolate frameworks (ZIF-12) in the presence of saturated solution of zinc sulfate. Subsequently, silver nanoparticles (Ag) were introduced onto the surface of N-PCNS/GCE to enhance conductivity and surface area, and serve as a standard signal. The MIP layer was formed on the Ag@N-PCNS/GCE surface through o-phenylenediamine (o-phen) electro-polymerization in the presence of the D-pencillamine (D-PAN) as a template. Detection of D-PAN relies on measuring ID-PAN/IAg response ratio employing differential pulse voltammetry (DPV). This ratio exhibits a linear correlation with the concentration of D-PAN in the dynamic linear range of 0.161–170 µM, exploiting LOD of 38.0 nM (S/N = 3). The electrochemical sensor offers numerous advantages including low detection limit, accuracy, stability, and sufficient degree of selectivity. Utilizing this platform, D-PAN-containing samples were efficiently analyzed with recovery percentages of 98.0–102.0 % and RSDs of 2.78–3.89 %, demonstrating the accuracy of the method.

Electropolymerized InZnSe@PtAg quantum dots@molecularly imprinted polymer on screen-printed carbon electrodes for the ultrasensitive detection of NS1 dengue virus protein with smartphone-based sensing in saliva

According to the World Health Organization (WHO), an estimated 100–400 million cases of dengue virus (DENV) infections are recorded annually with half of the global population being at risk of infection. Currently, there is no known treatment for DENV; however, early, rapid and accurate (sensitive and selective) detection can help to alleviate fatality rates. This work reports on the novel development of a point-of-care electrochemical biosensor for DENV using nanostructured InZnSe@PtAg quantum dots (QDs)-molecularly imprinted polymer (MIP) with smartphone-based detection functionality. Highly conductive InZnSe@PtAg QDs were newly synthesized in the presence of metal precursors, organic surfactants and ligands and surface capped with glutathione (GSH) using a ligand exchange reaction. PtAg was used as an electroactive shell layer on the InZnSe QDs core surface to increase the QDs conductivity. The GSH-InZnSe@PtAg QDs were drop-casted onto screen-printed carbon electrodes (SPCEs) and electropolymerized using cyclic voltammetry (CV) in the presence of o-phenylenediamine and the template DENV. The robust electropolymerization process allowed the overcoating of the MIP layer on the QDs/SPCE, where specific DENV size and shape cavities were created. Under optimal experimental conditions, DENV was rapidly, selectively and ultra-sensitively detected. Using differential pulse voltammetry (DPV), quantitative rebinding of DENV on the MIP@QDs/SPCE surface led to a steady decrease of the anodic peak current and a limit of detection of 1.36 pg/mL was obtained for DENV detection. Using a hand-held smartphone-based potentiostat, DENV was successfully detected in human saliva with satisfactory analytic recoveries.

Plasmonic Optical Fiber Sensors and Molecularly Imprinted Polymers for Glyphosate Detection at an Ultra-Wide Range

In this study, a surface plasmon resonance (SPR) sensor based on modified plastic optical fibers (POFs) was combined with a specific molecularly imprinted polymer (MIP), used as a synthetic receptor, for glyphosate (GLY) determination in aqueous solutions. Since GLY is a non-selective herbicide associated with severe environmental and health problems, detecting glyphosate in environmental and biological samples remains challenging. The selective interaction between the MIP layer and GLY is monitored by exploiting the SPR phenomenon at the POF’s gold surface. Experimental results show that in about ten minutes and by dropping microliter volume samples, the presented optical–chemical sensor can quantify up to three orders of magnitude of GLY concentrations, from nanomolar to micromolar, due to a thin MIP layer over the SPR surface. The developed optical–chemical sensor presents a detection limit of about 1 nM and can be used for onsite GLY measurements. Moreover, the experimental analysis demonstrated the high selectivity of the proposed POF-based chemical sensor.

Effect of Various Carbon Electrodes on MIP-Based Sensing Proteins Using Poly(Scopoletin): A Case Study of Ferritin.

Sensitivity in the sub-nanomolar concentration region is required to determine important protein biomarkers, e.g., ferritin. As a prerequisite for high sensitivity, in this paper, the affinity of the functional monomer to the macromolecular target ferritin in solution was compared with the value for the respective molecularly imprinted polymer (MIP)-based electrodes, and the influence of various surface modifications of the electrode was investigated. The analytical performance of ferritin sensing was investigated using three different carbon electrodes (screen-printed carbon electrodes, single-walled-carbon-nanotube-modified screen-printed carbon electrodes, and glassy carbon electrodes) covered with a scopoletin-based MIP layer. Regardless of the electrode type, the template molecule ferritin was mixed with the functional monomer scopoletin, and electropolymerization was conducted using multistep amperometry. All stages of MIP preparation were followed by evaluating the diffusional permeability of the redox marker ferricyanide/ferrocyanide through the polymer layer by differential pulse voltammetry. The best results were obtained with glassy carbon electrodes. The MIP sensor responded up to 0.5 µM linearly with a Kd of 0.30 µM. Similar results were also obtained in solution upon the interaction of scopoletin and ferritin using fluorescence spectroscopy, resulting in the quenching of the scopoletin signal, with a calculated Kd of 0.81 µM. Moreover, the binding of 1 µM ferritin led to 49.6% suppression, whereas human serum albumin caused 8.6% suppression.

Rational design of molecularly imprinted electrochemical sensor based on Nb2C-MWCNTs heterostructures for highly sensitive and selective detection of Ochratoxin a

Developing an efficient method for screening Ochratoxin A (OTA) in agriculture products is vital to ensure food safety and human health. However, the complex food matrix seriously affects the sensitivity and accuracy. To address this issue, we designed a novel molecularly imprinted polymer (MIP) electrochemical sensor based on multiwalled carbon nanotube-modified niobium carbide (Nb2C-MWCNTs) with the aid of the density functional theory (DFT). In this design, a glassy carbon electrode (GCE) was first modified by Nb2C-MWCNTs heterostructure. Afterward, the MIP layer was prepared, with ortho-toluidine as a functional monomer selected via DFT and OTA acting as a template on the surface of Nb2C-MWCNTs/GCE using in-situ electropolymerization. Electrochemical tests and physical characterization revealed that Nb2C-MWCNTs improved the sensor's active surface area and electron transmission capacity. Nb2C-MWCNTs had a good synergistic effect on MIP, endowing the sensor with high sensitivity and specific recognition of OTA in complex food matrix systems. The MIP sensor showed a wide linear range from 0.04 to 10.0 μM with a limit of detection (LOD) of 3.6 nM. Moreover, it presented good repeatability and stability for its highly antifouling effect on OTA. In real sample analysis, the recoveries, ranging from 89.77% to 103.70%, agreed well with the results obtained by HPLC methods, suggesting the sensor has good accuracy and high potential in practical applications.

Ultrasensitive detection of chlortetracycline in animal-origin food using molecularly imprinted electrochemical sensor based on SnS2/ZnCo-MOF and AuNPs

The chlortetracycline (CTC) residue in food poses a threat to human health. Therefore, developing sensitive, convenient and selective analytical methods for CTC detection is crucial. This study innovatively uses tin disulfide/bimetallic organic framework (SnS2/ZnCo-MOF) nanocomposites in conjunction with gold nanoparticles (AuNPs) to co-modify a glassy carbon electrode (GCE). Further, a molecularly imprinted polymer (MIP)-based electrochemical sensing platform Au-MIP/SnS2/ZnCo-MOF/Au/GCE (AZG) was fabricated for selective CTC detection. SnS2/ZnCo-MOF enhanced the stability and surface area of the AZG sensor. The presence of AuNPs facilitated electron transport between the probe and the electrode across the insulating MIP layer. The fixation of AuNPs and MIP via electropolymerization enhanced the selective recognition of this sensor and amplified its output signal. The AZG sensor demonstrated a wide linear detection range (0.1–100 μM), low detection limit (0.072 nM), and high sensitivity (0.830 μA μM−1). It has been used for detecting CTC in animal-origin food with good recovery (96.08%–104.60%).

Biocompatible MXene-reinforced molecularly imprinted membranes for simultaneous filtration and acetaminophen capture

In this study, the fabrication of biocompatible MXene-reinforced imprinted membranes (MX-AIM) capable of selectively capturing acetaminophen (APAP) molecules during filtration was demonstrated. The incorporation of MXene into a polymeric support membrane led to an overall improvement in both mechanical integrity and surface reactivity of the resulting composite, subsequently allowing efficient deposition of a molecularly imprinted polymer (MIP) layer on its surface. The synergy between the high surface reactivities of MXenes and the MIP layer rendered more adsorption sites, leading to the capture of approximately 32 % APAP on MX-AIM from a 200 ppm drug feed solution, compared to only ∼2 % for directly imprinted membranes. Additionally, these MXene-modified membranes exhibited high cell viabilities when tested against human monocytic cells, reaching up to >190 % cell proliferation. Overall, this research offers important insights on incorporating MXene nanofillers into membrane production, with the potential to overcome the challenges associated with applying the molecular imprinting technique to enhance the functionality of polymer materials.

Distance-based paper analytical devices integrated with molecular imprinted polymers for Escherichia coli quantification.

Thedevelopment of distance-based paper analytical devices (dPADs) integrated with molecularly imprinted polymers (MIPs) to monitor Escherichia coli (E. coli) levels in food samplesis presented. The fluidic workflow on the device is controlled using a designed hydrophilic bridge valve. Dopamine serves as a monomer for the formation of the E. coli-selective MIP layer on the dPADs. The detection principle relies on the inhibition of the E. coli toward copper (II) (Cu2+)-triggered oxidation of o-phenylenediamine (OPD) on the paper substrate. Quantitative detection is simply determined through visual observation of the residual yellow color of the OPD in the detection zone, which is proportional to E. coli concentration. The sensing exhibits a linear range from 25.0 to 1200.0CFUmL-1 (R2 = 0.9992) and a detection limit (LOD) of 25.0CFUmL-1 for E. coli detection. Additionally, the technique is highly selective with no interference even from the molecules that have shown to react with OPD to form oxidized OPD. The developed device demonstrates accuracy and precision for E. coli quantification in food samples with recovery percentages between 98.3 and 104.7% and the highest relative standard deviation (RSD) of 4.55%. T-test validation shows no significant difference in E. coli concentration measured between our method and a commercial assay. The proposed dPAD sensor has the potential for selective and affordable E. coli determination in food samples without requiring sample preparation. Furthermore, this strategy can be extended to monitor other molecules for which MIP can be developed and integrated into paper-microfluidic platform.

A novel fluorescent sensor for selective rifampicin detection based on the bio-inspired molecularly imprinted polymer-AgInS2/ZnS quantum dots.

A fluorescent sensing material based on the ternary core-shell quantum dots with outstanding optical properties and a bio-inspired molecularly imprinted polymer (MIP) as a recognition element has been prepared for selective detection of rifampicin (RFP). Firstly, AgInS2/ZnS core/shell quantum dots (ZAIS QDs) were prepared by a hydrothermal process. Then, the fluorescent sensor was prepared by coating these QDs by a dopamine-based MIP layer. The fluorescence of MIP@ZAIS QDs was quenched by RFP probably due to the photoinduced electron transfer process. The quenching constant was much higher for MIP@ZAIS QDs than the non-imprinted polymer@QDs, indicating that MIP@ZAIS QDs could selectively recognize RFP. Under the optimized conditions, the sensor had a good linear relationship at the RFP concentration range of 5.0 to 300nM and the limit of detection was 1.25nM. The respond time of the MIP@ZAIS QDs was 5min, and the imprinting factor was 6.3. It also showed good recoveries ranging from 98 to 101%, for analysis of human plasma samples. The method is simple and effective for the detection of RFP and offers a practical application for the rapid analysis of human plasma samples.

Optimization and performance evaluation of a fluorescent sensor for residual sulfonamide antibiotics in honey samples

AbstractIn the quest to address the mounting concerns over sulfonamide antibiotic residues in food, which pose significant threats to public health and food safety, this study introduces a cutting‐edge detection method. Surface molecular imprinting on silicon nanoparticles is harnessed to fabricate a novel fluorescent sensor that exploits the luminescent properties of cadmium telluride (CdTe) quantum dots. This innovative approach aims to detect residual sulfonamide antibiotics with high specificity and sensitivity. At the heart of this research is the development of a core‐shell nanostructure, where silicon dioxide serves as the core, and a molecularly imprinted polymers (MIPs) layer, tailored to recognize sulfamethazine (SM2), forms the shell. The pivotal advancement in this sensor design is the integration of highly fluorescent CdTe quantum dots within the MIPs layer, which significantly enhances the signal response, enabling the detection of SM2 with remarkable precision. The synthesis of this sensor employs a novel strategy, utilizing 3‐aminopropyltriethoxysilane as the functional monomer, while tetraethyl orthosilicate and ammonium hydroxide act as catalysts to facilitate the polymerization reaction. This meticulous process yields a stable core‐shell structure with active fluorescent properties. Experimental results reveal that under optimal conditions, the sensor exhibits a robust linear response to SM2 concentrations ranging from 10 to 60 μmol L−1, with a detection limit as low as 0.78 μmol L−1. Furthermore, when applied to real food samples, such as honey, the sensor not only demonstrates high recovery rates of 92.3%–98.1%, but also maintains a low relative standard deviation of less than 2.5%. The implications of this study are far‐reaching, offering a promising avenue for the rapid and reliable monitoring of antibiotic residues in the food supply chain, thereby safeguarding consumer health and upholding food safety standards.

The Failure of Molecular Imprinting in Conducting Polymers: A Case Study of Imprinting Picric Acid on Polycarbazole.

The aims of this study were to investigate the potential of utilising molecularly imprinted polycarbazole layers to detect highly toxic picric acid (PA) and to provide information about their performance. Quantum chemical calculations showed that strong interactions occur between PA and carbazole (bond energy of approximately 31 kJ/mol), consistent with the theoretical requirements for effective molecular imprinting. The performance of the sensors, however, was found to be highly limited, with the observed imprinting factor values for polycarbazole (PCz) layers being 1.77 and 0.95 for layers deposited on Pt and glassy carbon (GC) electrodes, respectively. Moreover, the molecularly imprinted polymer (MIP) layers showed worse performance than unmodified Pt or GC electrodes, for which the lowest limit of detection (LOD) values were determined (LOD values of 0.09 mM and 0.26 mM, respectively, for bare Pt and MIP PCz/Pt, as well as values of 0.11 mM and 0.57 mM for bare GC and MIP PCz/GC). The MIP layers also showed limited selectivity and susceptibility to interfering agents. An initial hypothesis on the reasons for such performance was postulated based on the common properties of conjugated polymers.

Distance-based paper analytical device for multiplexed quantification of cytokine biomarkers using carbon dots integrated with molecularly imprinted polymer.

This article introduces distance-based paper analytical devices (dPADs) integrated with molecularly imprinted polymers (MIPs) and carbon dots (CDs) for simultaneous quantification of cytokine biomarkers, namely C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) in human biological samples for diagnosis of cytokine syndrome. Using fluorescent CDs and MIP technology, the dPAD exhibits high selectivity and sensitivity. Detection is based on fluorescence quenching of CDs achieved through the interaction of the target analytes with the MIP layer on the paper substrate. Quantitative analysis is easily accomplished by measuring the distance length of quenched fluorescence with a traditional ruler and naked eye readout enabling rapid diagnosis of cytokine syndrome and the underlying infection. Our sensor demonstrated linear ranges of 2.50-24.0 pg mL-1 (R2 = 0.9974), 0.25-3.20 pg mL-1 (R2 = 0.9985), and 1.50-16.0 pg mL-1 (R2 = 0.9966) with detection limits (LODs) of 2.50, 0.25, and 1.50 pg mL-1 for CRP, TNF-α, and IL-6, respectively. This sensor also demonstrated remarkable selectivity compared to a sensor employing a non-imprinted polymer (NIP), and precision with the highest relative standard deviation (RSD) of 5.14%. The sensor is more accessible compared to prior methods relying on expensive reagents and instruments and complex fabrication methods. Furthermore, the assay provided notable accuracy for monitoring these biomarkers in various human samples with recovery percentages ranging between 99.22% and 103.58%. By integrating microfluidic systems, nanosensing, and MIPs technology, our developed dPADs hold significant potential as a cost-effective and user-friendly analytical method for point-of-care diagnostics (POC) of cytokine-related disorders. This concept can be further extended to developing diagnostic devices for other biomarkers.

Fabrication of 5-fluorouracil loaded multi-responsive molecularly imprinted poly (NVCL-co-MAA) coated black titanium dioxide nanocomposite as a chemo-photodynamic therapy agent

TiO2 nanoparticles (NPs) are commonly used in cancer photodynamic therapy due to their ultraviolet light–triggered properties. In this study, a molecularly imprinted polymer (MIP)-coated black TiO2 (b-TiO2) nanocomposites (NCs) were synthesized using free radical polymerization of thermosensitive N-vinyl caprolactam and pH-sensitive methacrylic acid functional monomers on the surface of b-TiO2 NPs. B-TiO2 NPs were prepared using calcination of as-synthesized white TiO2 NPs (w-TiO2) at high temperatures. The MIP layer was in-situ deposited on surface-activated b-TiO2 NPs with azobisisobutyronitrile as an initiator and uracil as a pseudo-template molecule of 5-Fluorouracil (5-FU). The samples were characterized using FTIR, NIR, XRD, DLS, TEM, BET and TGA analyses. The average crystallite sizes of w-TiO2, b-TiO2 NPs and the NCs were determined through Sharer's equation as 6.8, 10.36 and 12.61 nm, respectively, which were smaller than those obtained by DLS (7.5, 115 and 130.6 nm, respectively), indicating the aggregation of small particles during calcination at high temperatures. The equilibrium adsorption capacity of NCs and non-imprinted NCs with specific areas of 14.80 m2.g−1 and 7.611 m2.g−1, respectively, toward 5-FU was determined to be 80 and 25 mg.g−1, respectively, indicating that the imprinting process is highly efficient. Higher cumulative drug released in pH 5.5 and 41 ºC confirmed the remarkable potential of NCs as a pH/temperature-responsive delivery vehicle. Moreover, the NCs demonstrated enhanced photothermal/photodynamic and low hemolytic activity (< 5%) compared to b-TiO2 NPs. The findings indicate that NCs showed excellent potential for combining stimuli-responsive chemotherapy with photothermal/photodynamic therapy for melanoma treatment.

Towards Molecularly Imprinted Polypyrrole-Based Sensor for the Detection of Methylene Blue

This study is dedicated to molecularly imprinted polymer-based sensor development for methylene blue detection. The sensor was designed by molecular imprinting of polypyrrole with phenothiazine derivative methylene blue (MB) as a template molecule. The molecularly imprinted polymer (MIP) was deposited directly on the surface of the indium tin oxide-coated glass electrode by potential cycling. Different deposition conditions, the layer’s durability, and thickness impact were analysed. The working electrodes were coated with molecularly imprinted and non-imprinted polymer layers. Potential pulse chronoamperometry and cyclic voltammetry were used to study these layers. Scanning electron microscopy was used to determine the surface morphology of the polymer layers. The change in optical absorption was used as an analytical tool to evaluate the capability of the MIP layer to adsorb MB. Selectivity was monitored by tracking the optical absorption changes in the presence of Azure A. In the case of MB adsorption, linearity was observed at all evaluated calibration plots in the concentration range from 0.1 μM to 10 mM. The novelty of this article is based on the methodology in the fabrication process of the sensors for MB, where MB retains its native (non-polymerised) form during the deposition of the MIP composite.

MIP-Assisted 3-Hole POF Chip Faced with SPR-POF Sensor for Glyphosate Detection

The present study proposes the application of a recently developed optical–chemical sensor system to glyphosate detection. The device probes the refractive index variation in a chip based on a plastic optical fiber (POF) in which three orthogonal micro-holes were created and filled with an acrylic-based molecularly imprinted polymer (MIP). This sensitive chip, connected in series to a gold-coated SPR-POF platform, can modify the surface plasmon resonance (SPR) phenomena by exploiting the multimode characteristic of the POFs. Therefore, the gold film of the SPR-POF platform is not covered by the MIP layer, improving the sensor’s performance because the interaction between the analyte (glyphosate) and the polymer recognition cavities occurs in the core and not in the cladding of the waveguide. Indeed, the sample solution is dropped on the MIP-based chip while a water drop is constantly maintained above the gold surface of the reference SPR-POF platform to excite the surface plasmons, modulated by the MIP interaction with the target analyte. The device is here for the first time applied for glyphosate sensing in water samples. The high sensitivity and selectivity are proven, and tests on real samples highlight the good performances of the developed sensors.

Fabrication and application of molecularly imprinted polymer doped carbon dots coated silica stationary phase

Facing the difficulties in chromatographic separation of polar compounds, this investigation devotes to developing novel stationary phase. Molecularly imprinted polymers (MIPs) have aroused wide attention, owing to their outstanding selectivity, high stability, and low cost. In this work, a novel stationary phase based on carbon dots (CDs), MIP layer, and silica beads was synthesized to exploit high selectivity of MIPs, excellent physicochemical property of CDs, and outstanding chromatographic performances of silica microspheres simultaneously. The MIP doped CDs coated silica (MIP-CDs/SiO2) stationary phase was systematically characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area measurement, and carbon elemental analysis. Furthermore, the chromatographic performance of the MIP-CDs/SiO2 column was thoroughly assessed by using a wide variety of compounds (including nucleosides, sulfonamides, benzoic acids, and some other antibiotics). Meanwhile, the separation efficiency of the MIP-CDs/SiO2 stationary phase was superior to other kinds of stationary phases (e.g. nonimprinted NIP-CDs/SiO2, MIP/SiO2, and C18–SiO2). The results demonstrated that MIP-CDs/SiO2 column exhibited best performance in terms of chromatographic separation. For all tested compounds, the resolution value was not less than 1.60, and the column efficiency of MIP-CDs/SiO2 for thymidine was 22,740 plates/m. The results further indicate that the MIP-CDs/SiO2 column can combine the good properties of MIP, CDs, with those of silica microbeads. Therefore, the developed MIP-CDs/SiO2 stationary phase can be applied in the separation science and chromatography-based techniques.

Preparation of poly(1,8-diaminonaphthalene)-based molecularly imprinted polymers for rhodamine onto ITO/Au electrodes and analytical application by surface-enhanced Raman spectroscopy (SERS)

In this report, poly(1,8-diaminonaphthalene) as a molecularly imprinted polymer (MIP) coated on gold nanoparticles (nano Au) dispersed on ITO electrode was prepared. While nano Au strongly enhance the Raman signal of the analyte, MIP layer allows to selective trap and enrich the analyte molecules close to the Au surface. In fact, by building a polymer matrix around target molecules, in this case is rhodamine B and then extraction of the imprinted molecules, we can create the specific cavities in the MIP shell with a 3D structure complementary to the template molecule in shape and chemical functionality. The rhodamine molecules on ITO/Au/MIP substrate were detected using surface-enhanced Raman spectroscopy (SERS) with an enhancement factor of 106. The SERS peak intensity at 611 and 771 cm-1 was found to be proportional to the Rhodamine concentration with correlation coefficients of 0.993 and 0.935, respectively. These results open up prospects for development of poly(1,8-diaminonaphthalene) as a molecularly imprinted polymer for applications in plasmonic sensing.

Novel graphene electrochemical transistors incorporating zirconia inorganic molecular imprinted layer：Design, construction and application for highly sensitive and selective detection of acetaminophen

Owing to their intrinsic amplifying effect together with chemical stability, graphene electrochemical transistor sensors (GECTs) are gaining momentum for sensing applications. However, the surface of GECTs for different detection substances must be modified with different recognition molecules, which was cumbersome and lack a universal method. Molecularly imprinted polymer (MIP) is a kind of polymer with specific recognition function for given molecules. Here, MIP and GECTs were combined to effectively solve the problem of weak selectivity of GECTs, and achieve the high sensitivity and selectivity of MIP-GECTs equipment in detecting acetaminophen (AP) in complex urine environment. A novel molecular imprinting sensor based on Au nanoparticles modified zirconia (ZrO2) inorganic molecular imprinting membrane on reduced graphene oxide (ZrO2-MIP-Au/rGO) was proposed. ZrO2-MIP-Au/rGO was synthesized by one-step electropolymerization using AP as template, ZrO2 precursor as the functional monomer. The –OH group on ZrO2 and the –OH/–CONH– group on AP were easily bonded by hydrogen bonding to form a MIP layer on the surface, which allows the sensor to have a large number of imprinted cavities for AP specific adsorption. As a proof of method, the GECTs based on ZrO2-MIP-Au/rGO functional gate electrode has the characteristics of wide linear range (0.1 nM-4 mM), low detection limit (0.1 nM) and high selectivity for AP detection. These achievements highlight the introduction of specific and selective MIP to GECTs with unique amplification function, which could effectively solve the problem of selectivity of GECTs in complex environments, suggesting the potential of MIP-GECTs in real-time diagnosis.

A fluorometric sandwich biosensor based on molecular imprinted polymer and aptamer modified CdTe/ZnS for detection of aflatoxin B1 in edible oil

Aflatoxin B1 (AFB1) is a toxic metabolite produced by fungi with substantial environmental and health concerns. Thus, the detection of AFB1 has attracted increasing attention. In this study, a fluorometric sandwich biosensor was developed for the detection of AFB1, which was prepared by combining molecularly imprinted polymer (MIP) with an aptamer. Porous carbon (PC) generated by the carbonization of ZIF-8 provided abundant sites for the MIP layer to achieve high-performance recognition of AFB1. The aptamer-modified CdTe/ZnS achieved efficient sandwich analysis of AFB1 as a signal probe. The sandwich biosensor exhibited excellent selectivity and high sensitivity with a dynamic linear range of 0.01–20 ng/mL and good reliability in spiked edible oil samples as low as 4.0 pg/mL. In sum, the developed sandwich biosensor is promising for the detection of AFB1 in food and the environment, with great potential in the control of other challenging food hazards.

Construction of molecularly imprinted voltammetric sensor based on Cu[sbnd]N[sbnd]C polyhedron porous carbon from Cu doping ZIF-8 for the selective determination of norfloxacin

In this paper, a protocol of the integration of Cu doped porous carbon (CuCN) and molecularly imprinted polymer (MIP) was proposed to develop a sensitive, selective, and stable electrochemical sensor toward the determination of norfloxacin (NFX). Field-emission scanning electron microscopy and transmission electron microscope, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller analysis and thermogravimetric analyzer, cyclic voltammetry, and electrochemical impedance spectroscopy were used to characterize the doping materials and the MIP film. CuNC porous carbon was prepared by high-temperature carbonizing Cu/ZIF-8 precursor. The doping of Cu into ZIF-8 allows not only enhancing the conductivity for the sensor by giving active sites, but also favors the great porous structure and active surface area by prohibiting the structure collapse of ZIF-8 polyhedron. The MIP layer was prepared by in-situ electrochemical polymerization of dual monomers of dopamine and resorcinol on glassy carbon electrode (GCE) modified by CuNC. For the electrochemical detecting, the condition of the ratio of two functional monomers, functional monomer to template molecular, the number of electric polymerization cycles, pH, and incubation time were optimized. The proposed MIP/CuNC/GCE sensor allows the sensitive detecting toward NFX with the linear ranges of 0.01–0.5 and 0.5–100 μM and the limit of detection of 3.33 nM (S/N = 3). In addition, the sensor has good selectivity, repeatability, reproducibility, and stability. In terms of practical application, the sensor is feasible and robust in determination of NFX in the commercially available tablet with the average recovery of 96.72 %–103.88 % and RSD less than 5 %.