Imprinted Polymer Nanocomposites Research Articles

Synthesis and characterization of core–shell magnetic molecularly imprinted polymer nanocomposites for the detection of interleukin-6

Interleukin-6 (IL-6) belongs to the cytokine family and plays a vital role in regulating immune response, bone maintenance, body temperature adjustment, and cell growth. The overexpression of IL-6 can indicate various health complications, such as anastomotic leakage, cancer, and chronic diseases. Therefore, the availability of highly sensitive and specific biosensing platforms for IL-6 detection is critical. In this study, for the first time, epitope-mediated IL-6-specific magnetic molecularly imprinted core–shell structures with fluorescent properties were synthesized using a three-step protocol, namely, magnetic nanoparticle functionalization, polymerization, and template removal following thorough optimization studies. The magnetic molecularly imprinted polymers (MMIPs) were characterized using dynamic and electrophoretic light scattering (DLS and ELS), revealing a hydrodynamic size of 169.9 nm and zeta potential of +17.1 mV, while Fourier transform infrared (FTIR) spectroscopy and fluorescence spectroscopy techniques showed characteristic peaks of the polymer and fluorescent tag, respectively. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) investigations confirmed the successful encapsulation of the magnetic core within the ca. 5-nm-thick polymeric shell. The MMIP-based electrochemical sensing platform achieved a limit of detection of 0.38 pM within a linear detection range of 0.38–380 pM, indicating high affinity (dissociation constant KD = 1.6 pM) for IL-6 protein in 50% diluted serum samples. Moreover, comparative investigations with the non-imprinted control polymer demonstrated an imprinting factor of 4, confirming high selectivity. With multifunctional features, including fluorescence, magnetic properties, and target responsiveness, the synthesized MMIPs hold significant potential for application in various sensor techniques as well as imaging.

Selective extraction of apixaban from plasma by dispersive solid-phase microextraction using magnetic metal organic framework combined with molecularly imprinted polymer nanocomposite.

This research aims to synthesize a specific and efficient sorbent to use in the extraction of apixaban from human plasma samples and its determination by high-performance liquid chromatography-tandem mass spectrometry. High specific surface area of metal-organic framework, magnetic property of iron oxide nanoparticles, selectively of molecular imprinted polymer toward the analyte, and the combination of dispersive solid-phase extraction method with a sensitive analysis system provided an efficient analytical method. In this study, first, a molecularly imprinted polymer combined with magnetic metal organic framework nanocomposite was prepared and then characterized using different techniques. Then the sorbent particles were used for selective extraction of the analyte from plasma samples. The efficiency of the method was improved by optimizing effective parameters. According to the validation results, wide linear range (1.02-200ng mL-1 ), acceptable coefficient of determination (0.9938), low limit of detection (0.32ng mL-1 ) and limit of quantification (1.02ng mL-1 ), high extraction recovery (78%), and good precision (relative standard deviations ≤ 2.9% for intra- (n=6) and interday (n=6) precisions) were obtainable using the proposed method. These outcomes showed the high potential of the proposed method for screening apixaban in the human plasma samples.

An Electrochemical Sensor for Sulfadiazine Determination Based on a Copper Nanoparticles/Molecularly Imprinted Overoxidized Polypyrrole Composite.

To protect consumers from risks related to overexposure to sulfadiazine, total residues of this antibacterial agent in animal-origin foodstuffs not exceed international regulations. To this end, a new electrochemical sensor based on a molecularly imprinted polymer nanocomposite using overoxidized polypyrrole and copper nanoparticles for the detection of sulfadiazine is elaborated. After optimization of the preparation of the electrochemical sensors, their differential pulse voltammetric signal exhibits an excellent stability and reproducibility at 1.05 V, with a large linear range between 10-9 and 10-5 mol L-1 and a low detection limit of 3.1 × 10-10 mol L-1. The produced sulfadiazine sensor was successfully tested in real milk samples. The combination of the properties of the electrical conduction of copper nanoparticles with the properties of the preconcentration of the molecularly imprinted overoxidized polypyrrole allows for the highly sensitive detection of sulfadiazine, even in real milk samples. This strategy is new and leads to the lowest detection limit yet achieved, compared to those of the previously published sulfadiazine electrochemical sensors.

Sensitive detection of synthetic cannabinoids in human blood using magnetic polydopamine molecularly imprinted polymer nanocomposites.

Synthetic cannabinoids (SCs) are a series of artificial chemical substances with pharmacological properties similar to those of natural cannabinoids and their abuse poses a great risk to social security and human health. However, the highly sensitive detection of low concentrations of SCs in human serum remains a great challenge. In this work, we developed a highly sensitive, rapid and highly selective method for the detection of SCs in human serum. Magnetic molecularly imprinted polymer (MIP) nanocomposites were prepared through self-polymerization of dopamine and template molecules on the surfaces of magnetic beads. 9H-Carbazole-9-hexanol (9CH) was used as a template molecule because of its long chain structure shared with six synthetic cannabinoids and its ability to provide specific recognition sites. With these magnetic MIP nanoparticles, six SCs could be rapidly and effectively extracted from human blood. The concentrations of six SCs could be accurately determined by high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis. The limits of detection were in the range of 0.1-0.3 ng mL-1. The proposed method is characterized by high sensitivity and selectivity, and has great potential for application in the analysis of practical samples.

Fluorescent molecularly imprinted polymer nanocomposite for solid-phase extraction and fluorimetric determination of hydrochlorothiazide.

We report herein a fluorescent molecularly imprinted polymer (FMIP) for the solid-phase extraction (SPE) and fluorimetric determination of hydrochlorothiazide (HCTZ) in water. The FMIP is based on fluorescent polystyrene nanoparticles embedded within a molecularly imprinted polyaniline (PANI) matrix. The operational adsorption parameters such as the initial HCTZ concentration, incubation time and the solution pH were found to influence the removal efficiency. At optimum conditions, a high adsorption capacity of the FMIP was found (2.08 mg g-1). Evidence of the adsorption process was confirmed by the change in the FMIP physicochemical properties measured by FTIR absorption spectroscopy and electron microscopy. Based on the regression R2 values and the consistently low values of the adsorption statistical error functions, equilibrium data were best fitted to both Freundlich and Temkin isotherms. Moreover, the pseudo-second-order kinetic model described the adsorption kinetics, and the mechanism of the adsorption process was explained by the intraparticle diffusion model. Upon studying adsorption thermodynamics, negative ΔG values (-26.18 kJ mol-1 at room temperature) were obtained revealing that the adsorption process is spontaneous. Interestingly, the maximum adsorption capacity was obtained at 298 K, pH 7.0, and using a high HCTZ concentration, thus revealing the suitability of the proposed FMIP for easy and fast SPE of HCTZ. The FMIP showed an imprinting factor of 1.19 implying the selectivity over the corresponding FNIP. Eventually, the proposed FMIP was successfully applied to the spectrofluorimetric determination of HCTZ in aqueous samples with %recovery values close to 100%.

Enzyme-Free Glucose Monitoring Patch

Monitoring of glucose levels in non-invasive biofluids, such as saliva and sweat, can advance personal health tracking. However, the approach remains challenging due to the low glucose concentration in saliva and sweat, about 100 times lower than in the blood. Commercial glucose sensors rely on glucose oxidase to measure blood glucose levels with enzyme reactions. The enzyme activity varies with pH, oxygen level, and temperature (more than 40ºC). Also, the method often suffers from cross-reactivity with other sugar molecules, such as maltose and xylose [1]. Thus, it is crucial to develop highly sensitive and stable non-enzymatic sensors for detecting glucose in non-invasive biological fluids.In this work, we present an enzyme-free, reagent-free electrochemical glucose monitoring patch based on a glucose imprinted polymer nanocomposite. The nanocomposite comprises redox-active chitosan-ferrocene (Cs-Fc) wrapped multi-walled carbon nanotubes (MWCNTs). The Cs-Fc is a polymer with covalently secured redox-active ferrocene, effectively preventing the out leakage of redox substances [2]. The incorporation of MWCNTs increases the surface area, conductivity, and electron transfer rate. The glucose imprinted layer was grown on the surface of the nanocomposite by electropolymerization of functional monomers o-phenylenediamine (o-PD) and 3-aminophenylboronic acid (APBA) in the presence of glucose templates. The successful removal of template molecules created glucose specific recognition sites in the polymer matrices. The sensor directly detected the presence of glucose upon their binding into these cavities. The electrochemical property of the modified sensor was characterized by cyclic voltammetry (CV) in a potential range of 0-0.5 V at a scan rate of 100 mVs-1 in 1x PBS (pH 7.4) solution. For glucose sensing, the sensor was immersed in a sample solution containing different glucose concentrations for 30 min. We have optimized the composition ratio and assay conditions for sensitive glucose detection. Preliminary results indicated a change in redox peak current of ~2.7 times relative to the control upon adding 1 mM glucose, as shown in Figure 1. The proposed glucose patch is label-free, reagentless, cost-effective, easy fabrication, and expected to be utilized for sensitive and selective glucose detection from sweat.

Fabrication of a near-infrared fluorescence-emitting SiO2-AuZnFeSeS quantum dots-molecularly imprinted polymer nanocomposite for the ultrasensitive fluorescence detection of levamisole

Levamisole is an anthelminthic drug that is usually used as a cutting agent to lace illicit cocaine samples and has been classified as a dangerous substance. In this work, we report on the fabrication of a novel fluorescence sensor for levamisole using AuZnFeSeS alloyed quantum dots (QDs)-molecularly imprinted polymer (MIP) nanocomposite. Firstly, organic-phased AuZnFeSeS QDs were synthesized via the organometallic hot-injection pyrolysis of metal precursors, surfactants, and organic ligands. Silica (SiO2) was then encapsulated on the QDs surface to render it compact, stable, and biocompatible. Via a free radical polymerization approach, a robust MIP shell templated with levamisole was coated around the SiO2-AuZnFeSeS QDs surface to form a AuZnFeSeS QDs@MIP core/shell nanocomposite. Passivation of the SiO2-AuZnFeSeS QDs core surface with the MIP shell led to radiative exciton recombination process, whereby the QDs fluorescence was enhanced. Interestingly, the SiO2-AuZnFeSeS QDs was characterized by rod-shaped and spherical-shaped particle morphology. Under optimum conditions, the fluorescence of the AuZnFeSeS QDs@MIP nanocomposite was quenched in the presence of levamisole and was selective against other tested drugs. Quantitative detection was achieved in the concentration range of 0.5 – 100 μM with a limit of detection of 0.05 μM (47.4 nM). Validation of the MIP-levamisole affinity was demonstrated by the superior sensitivity of the AuZnFeSeS QDs@MIP over the AuZnFeSeS QDs@NIP (non-templated material). Levamisole was successfully detected in a mixed drug sample containing cocaine with satisfactory analytical recoveries. This work is the first reported use of a cadmium-free quintenary alloyed QDs@MIP nanocomposite fluorescence detection system for levamisole.

A novel electrochemical sensor based on metal nanoparticles and molecularly imprinted polymer nanocomposite with biological applications

Metal nanoparticles trapped in a biopolymer composite due to electrical conductivity properties improve electrochemical sensors with biomedical and environmental applications. The study aims are to design a novel molecularly imprinted polymer (MIP) composite based on magnetic graphene oxide (Fe3O4@GO) modified silica (SiO2) and gold nanoparticles (AuNPs) to electrochemical detect serotonin (5-hydroxytryptamine, 5-HT). A suitable amount of 5-HT is effective on motivational functions and the environment because it is a serotonergic neurotransmitter. But the desired nanocomposite may have a relatively low recognition, therefore must be in choosing the type of functional monomer be careful. In this regard, the design of the electrochemical sensor began by synthesis of Fe3O4@GO-SiO2@AuNPs nanocomposite. Then, MIP electropolymerization was carried out by using p-aminothiophenol (PATP)-functionalized Fe3O4@GO-SiO2@AuNPs nanocomposite in the presence of 5HT as a template molecule. Electrochemical polymerization of MIP nanocomposite was developed using cyclic voltammetry (CV) and the electrochemical properties of 5-HT were studied use differential pulse voltammetry (DPV) technology in the 5HT solution. After optimization of preparation and measurement conditions on the designed sensor, the 5HT concentration range is 0.1 μM to 10 μM linearly, and the detection limit was 1 × 10-5 μM (S / N = 3). The wide concentration range and low detection limit were presented metal nanoparticles functionalized MIP with appropriate functional monomer have a great effect on the performance of the sensor. Furthermore, PATP-functionalized metal nanoparticles increase the conductivity and recognition of the prepared MIP electrochemical sensor to the quantification of 5-HT in biological samples with high selectivity and recovery.

Selective magnetic solid-phase extraction of amide herbicides from fish samples coupled with ultra-high-performance liquid chromatography with tandem mass spectrometry.

An efficient magnetic dummy template molecularly imprinted polymer nanocomposite was prepared using multi-walled carbon nanotubes as a support and metolachlor deschloro as a dummy template. The obtained nanocomposites were characterized using Fourier transform infrared spectroscopy, vibrating sample magnetometry, scanning electron microscopy, and transmission electron microscopy. The adsorption performance of the obtained nanocomposites was evaluated through binding experiments, including static adsorption, kinetic adsorption, and selective recognition studies. The obtained nanocomposites were successfully applied as selective sorbents for the magnetic solid-phase extraction of seven amide herbicides (alachlor, acetochlor, pretilachlor, butachlor, metolachlor, diethatyl ethyl, and dimethachlor) coupled with liquid chromatography-tandem mass spectrometry from fish samples. Under the optimized conditions, the limit of detection was 0.01-0.1 μg/kg. The obtained recoveries of the amide herbicides from the fish samples were in the range of 88.0 to 102.1% with a relative standard deviation of less than 7.5%. This method, which eliminated the effect of template leakage on qualitative and quantitative analysis was found to be superior to the methods reported in the literature. The results indicated that it could be successfully applied to analyze amide herbicides in fish samples with satisfactory recoveries.

Design and synthesis of a new magnetic molecularly imprinted polymer nanocomposite for specific adsorption and separation of diazinon insecticides from aqueous media

Today, molecularly imprinted polymers have received much engrossment as selective adsorbents and substrates. In the present study, a magnetic molecularly imprinted polymer (MIP) based on clay, graphene oxide and polydopamine was synthesized and used for adsorption and specific entrapment of Diazinon pesticide. The magnetic MIP nanocomposite was characterized by XRD, FT-IR, SEM, VSM, and AFM methods. The response surface method (RSM) was used to optimize and modeling the effective parameters of the adsorption of Diazinon by this polymer, and the results were compared with an artificial neural network (ANN). The results showed magnetic saturation of GO/Clay/Fe3O4@PDA MIP nanocomposite is equal to 8.28 emu/g, average particle size, average surface roughness and imprinting factor of this polymer are equal to 105 nm, 66.72 nm and 2.35, respectively. This polymer has a very selective ability to adsorption of Diazinon by removal percentage equal to 99.85 at pH = 7, the concentration of Diazinon = 1.45 ppm, the dosage of polymer = 1.24 g/L, time = 16 min. Also, the RSM results showed that the model included the effect of parameters on the absorption efficiency is a quadratic polynomial equation with the coefficient of determination equal to 0.98% and the most effective parameter on removal percentage is the dosage of the polymer. The artificial neural network with 11 neurons in the hidden layer with the coefficient of determination of 0.96% was also suitable for modeling the absorption process. Compared to the ANN model, the RSM model has better capability and lower error values. Freundlich isothermal models and pseudo-second-order and Elovich kinetic models in different concentrations of Diazinon were appropriate for explanation the adsorption process. The mechanism of Diazinon adsorption by MIP nanocomposite was influenced by intraparticle and extraparticle diffusion. Also, GO/Clay/Fe3O4@PDA MIP nanocomposite has an adsorption capacity of more than 98% up to nine cycles of the adsorption/desorption process.

Luminescent molecularly imprinted polymer nanocomposites for emission intensity and lifetime rapid sensing of tenuazonic acid mycotoxin

Tenuazonic acid ((5S)-3-acetyl-5-[(2S)-butan-2-yl]-4-hydroxy-2,5-dihydro-1H-pyrrol-2-one, TeA) is a widespread Alternaria fungi mycotoxin in food produce. This toxin may be allergenic and provoke hay fever and asthma. Therefore, rapid methods to selectively detect TeA are needed. With this aim, we have engineered a novel trifunctional (red-luminescent, polymerizable, TeA-sensitive) ruthenium(II)-bipyridyl complex with 2,2′-biimidazole. Its peripheral N–H moieties recognize the enolate form of 1,3-dicarbonyl compounds (including TeA) in partially aqueous media. Such a binding decreases the luminescence intensity and lifetime (0.2 μs) of the Ru(II) probe. The probe also bears acrylate groups that allow radical copolymerization with methacrylamide and ethylene glycol dimethacrylate in the presence of TeA, to yield 9-nm thick luminescent molecularly imprinted polymer (MIP) shells onto 200-nm silica cores. The SiO2@Ru-MIP nanocomposite displays a very fast response (<5 s) suitable for real-time detection of TeA. No cross-sensitivity to other common food mycotoxins that also contain a β-hydroxycarbonyl moiety (alternariol, β-zeranol, cyclopiazonic acid) is observed. Detection limits of 63.8 μg L⁻1 and 75.2 μg L⁻1 under steady-state and time-resolved luminescence detection, respectively, have been measured without further optimization. The use of emission lifetime variations to monitor the levels of a target analyte has never been reported for a luminescent MIP-based sensor.

Design and Synthesis of a New Magnetic Molecularly Imprinted Polymer Nanocomposite for Specific Adsorption and Simultaneous Determination of Diazinon Insecticides from Aqueous Media

Design and Synthesis of a New Magnetic Molecularly Imprinted Polymer Nanocomposite for Specific Adsorption and Simultaneous Determination of Diazinon Insecticides from Aqueous Media

Highly efficient Imprinted Polymer Nanocomposites for photocatalytic desulfurization of real diesel fuel

The well-prepared imprinted nanocomposite polymer (MIP/AgPx) was used as a highly photo-active material in the oxidative desulfurization process. The synthesized nanocomposites were characterized using various analytical techniques including X-ray diffraction (XRD), UV diffuse reflectance spectroscopy (UV-DR), Fourier-transform infrared spectroscopy (FTIR), Photoluminescence spectroscopy (PL), and scanning electron microscope (SEM). The experimental parameters of the photo-desulfurization process, such as the source of radiations, the dosage of catalyst, reaction time, and addition of oxidizing agents such as hydrogen peroxide (H 2 O 2 )/acetic acid, were evaluated. The photo-degradation efficiency of dibenzothiophene (DBT, 450 ppm) was achieved ∼ 96% at room temperature in the presence of oxidizing agents with irradiation time 2h using xenon lamp (420 nm, 500 W). The removal efficiency enhanced to be 98% at the optimum conditions with high-quality diesel index: 96.17. The photocatalytic activity was attributed to the reduction of the recombination rate between electrons & holes and fast charge transfer. Furthermore, the MIP/AgP25 can be quickly recovered and reused by simple filtration for six times with a negligible decrease in the catalytic performance. • The imprinted polymer MIP/AgPx was used in the oxidative desulfurization process. • The catalytic photochemical process has highly proven desulfurization performance. • The treatment of real diesel leads to 96% degradation of organic sulfur compounds. • The prepared composite proven to be reused for 6 times with high activity and stability.

Magnetic titanium dioxide embedded molecularly imprinted polymer nanocomposite for the degradation of diuron under visible light

The present study aims at the synthesis of a magnetic titanium dioxide (mTiO2) incorporated conducting molecularly imprinted polymer (mTiO2-MIP) for the visible light driven degradation of a priority pollutant, diuron (DU). The prepared photocatalyst, mTiO2-MIP was characterized using FT-IR, XRD, SEM, AFM, TEM, VSM, XPS, UV–Vis DRS, photoluminescence spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopic techniques. The conducting MIP layer not only enhanced the selectivity of the catalyst but also act as a photosenstizer. Enhanced photocatalytic degradation of DU was observed with mTiO2-MIP as photocatalyst compared to mTiO2 under visible light.

Core-Shell Molecularly Imprinted Polymer Nanocomposites for Biomedical and Environmental Applications.

Core-shell polymers represent a class of composite particles comprising of minimum two dissimilar constituents, one at the center known as a core which is occupied by the other called shell. Core-shell molecularly imprinting polymers (CSMIPs) are composites prepared via printing a template molecule (analyte) in the coreshell assembly followed by their elimination to provide the everlasting cavities specific to the template molecules. Various other types of CSMIPs with a partial shell, hollow-core and empty-shell are also prepared. Numerous methods have been reported for synthesizing the CSMIPs. CSMIPs composites could develop the ability to identify template molecules, increase the relative adsorption selectivity and offer higher adsorption capacity. Keen features are measured that permits these polymers to be utilized in numerous applications. It has been developed as a modern technique with the probability for an extensive range of uses in selective adsorption, biomedical fields, food processing, environmental applications, in utilizing the plant's extracts for further applications, and sensors. This review covers the approaches of developing the CSMIPs synthetic schemes, and their application with special emphasis on uses in the biomedical field, food care subjects, plant extracts analysis and in environmental studies.

Magnetic ferroferric oxide and polydopamine molecularly imprinted polymer nanocomposites based electrochemical impedance sensor for the selective separation and sensitive determination of dichlorodiphenyltrichloroethane (DDT)

Dichlorodiphenyltrichloroethane (DDT) is a kind of broad-spectrum insecticides, which is potentially toxic and persistently threatens the safety of environment and food, due to their stability in nature and difficulty to degrade. For the first time, a novel impedance chemical sensor based on magnetic Fe3O4 and polydopamine molecularly imprinted polymer magnetic nanoparticles (PDA@Fe3O4 MIP MNPs) was designed. Bisphenol A (BPA) and dopamine were used as virtual template molecules and functional monomer for MIP synthesis, respectively. Recognition cavities formed in PDA layers could specifically recognize and effectively adsorb DDT molecules, with the help of virtual templates that had similar molecular structure to DDTs. The as-prepared PDA@Fe3O4-MIP MNPs could be used for specific adsorption and efficient extraction of target molecules 4,4′-DDT from food samples. The electrochemical impedance of the PDA@Fe3O4-MIP MNPs increased sensitively with the adsorption of 4,4′-DDT, the correlationship between of the electrochemical impedance response and the concentration of 4,4′-DDT were applied in the construction of electrochemical impedance sensors for the determination of 4,4′-DDT. The sensor showed a good linear relationship between the charge transfer resistance (Rct) and the 4,4′-DDT concentration over a range from 1 × 10−11 to 1 × 10−3 mol L−1 with a detection limit of 6 × 10−12 mol L−1. The sensor also exhibited excellent sensitivity and selectivity as well as high stability for the detection of pesticide residues and other environmentally harmful chemicals in various food samples.

A convenient synthesis of NiO-CuS/molecularly imprinted polymer nanocomposites with highly enhanced adsorption activity and selectivity for removal of Letrozole

ABSTRACTIn this study, Novel NiO-CuS nanocomposites were prepared by simple chemical method. The goal of this project was to apply the Letrozole (Anti-estrogen drug) template molecularly imprinted polymer (MIP) for the selective removal of Letrozole from aqueous samples. The NiO-CuS nanocomposites and NiO-CuS/MIP nanocomposites were specified by field emission scanning electron microscopy, X-ray diffraction, photoelectron spectroscopy, N2 adsorption-desorption, and thermogravimetric analysis. The performance of the NiO-CuS and NiO-CuS/MIP nanocomposites was analyzed by optimizing various removal factors. The optimized data for adsorption process were 0.01 g/L: MIP, contact time: 40 min and pH: 7.0. The data was evaluated best by pseudo 1st and 2nd order equation which revealed a chemical adsorption of letrozole onto NiO-CuS and NiO-CuS/MIP particles, respectively. The result of R2 values indicated that the adsorption data followed the Langmuir isotherm equation which defined that the binding agent happened on the homogeneous sites of adsorbent.

Well-Designed High Selective Carbon Molecularly Imprinted Polymer Nanocomposite Based on a Green Synthesis Strategy for Solid-Phase Extraction of Tetracyclines Residues in Food Samples

Herein, a well-designed hydrophilic tetracycline-imprinted polymer with high selectivity was synthesized with a three-dimensional carbon nanocomposite of graphene oxide (GO) and carbon nanotube (CNT) by a green synthesis method of freeze-drying. The synthesized materials with super selectivity, which could distinguish high similar structural analogues of tetracycline (TC) and oxytetracycline (OTC), and the maximum adsorption capacity for TC (MW 444.44, 19.31 mg g−1) was 3-fold greater than its structural analogue of OTC (MW 460.43, 6.48 mg g−1). The synthesized materials were characterized by Fourier-transform infrared spectrometry (FT-IR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), and thermogravimetry analysis (TGA). The adsorption mechanism and adsorption performance of the synthesized materials were detailed studied via the adsorption isotherms, adsorption kinetics, competitive adsorption, and selective adsorption experiments. A method was established by using the synthesized materials as the adsorbent for solid-phase extraction (SPE) of TCs residues in food samples and then detected by high-performance liquid chromatography (HPLC). Under the optimum conditions, the detection limit of this method (MDL) was 0.127 μg kg−1. The extraction efficiency of this method was performed in three real samples (milk, chicken, and fish) that spiked with tetracycline of three levels (5, 10, 20 μg kg−1). The results showed good recoveries ranging from 85.58 ± 0.19 to 116.87 ± 8.92% (S/N = 3), respectively.

Titanium dioxide and polypyrrole molecularly imprinted polymer nanocomposites based electrochemical sensor for highly selective detection of p-nonylphenol

We developed a new electrochemical sensor based on TiO2 and polypyrrole (PPy) molecularly imprinted polymer (MIP) nanocomposites for the high selective detection of p-nonylphenol in food samples, which is considered as a kind of endocrine disrupting chemical and harmful to human health. With p-nonylphenol as template molecules, the molecularly imprinted polymer was synthesized by the chemical oxidative polymerization of pyrrole and deposited on the surface of TiO2 nanoparticles to form partially encapsulated PPy@TiO2 nanocomposites, denoted as NP-PPy@TiO2 MIP. p-Nonylphenol was bound in the PPy matrix through hydrogen bond and π-π interaction between p-nonylphenol and PPy skeleton. NP-PPy@TiO2 MIP nanocomposites were modified onto glassy carbon electrode (GCE) and p-nonylphenol molecules were excluded from PPy layers by potentiostatic sweeping at the potential of 1.3 V. The as-prepared electrochemical sensor obtained a large amount of micro cavities in PPy layer which could specially recognize and combine target molecules p-nonylphenol. After special adsorption of p-nonylphenol from samples, p-nonylphenol embedded in the PPy layer exhibited a strong differential pulse voltammetry (DPV) response at 0.56 V, which can be used for the detection of p-nonylphenol with a linearly proportional concentration range of 1.0 × 10−8 to 8 × 10−5 mol/L and a detection limit of 3.91 × 10−9 mol/L. The good stability, reproducibility and specificity of the resulting MIP electrochemical sensor are demonstrated. It might open a new window for investigation of selectively electrochemical sensing of small organic molecules from their analogues with the molecular imprinting technique.

Highly Selective Copper Ion Imprinted Clay/Polymer Nanocomposites Prepared by Visible Light Initiated Radical Photopolymerization.

There is an urgent demand worldwide for the development of highly selective adsorbents and sensors of heavy metal ions and other organic pollutants. Within these environmental and public health frameworks, we are combining the salient features of clays and chelatant polymers to design selective metal ion adsorbents. Towards this end, the ion imprinting approach has been used to develop a novel nanohybrid material for the selective separation of Cu2+ ions in an aqueous solution. The Cu2+-imprinted polymer/montmorillonite (IIP/Mt) and non-imprinted polymer/montmorillonite (NIP/Mt) nanocomposites were prepared by a radical photopolymerization process in visible light. The ion imprinting step was indeed important as the recognition of copper ions by IIP/Mt was significantly superior to that of NIP/Mt, i.e., the reference nanocomposite synthesized in the same way but in the absence of Cu2+ ions. The adsorption process as batch study was investigated under the experimental condition affecting same parameters such as contact time, concentration of metal ions, and pH. The adsorption capacity of Cu2+ ions is maximized at pH 5. Removal of Cu2+ ion achieved equilibrium within 15 min; the results obtained were found to be fitted by the pseudo-second-order kinetics model. The equilibrium process was well described by the Langmuir isothermal model and the maximum adsorption capacity was found to be 23.6 mg/g. This is the first report on the design of imprinted polymer nanocomposites using Type II radical initiators under visible light in the presence of clay intercalated with hydrogen donor diazonium. The method is original, simple and efficient; it opens up new horizons in the general domain of clay/polymer nanocomposites.