Surface Molecular Imprinting Technique Research Articles

A novel surface molecularly imprinted polymer as the solid-phase extraction adsorbent for the selective determination of ampicillin sodium in milk and blood samples

Surface molecularly imprinted polymers (SMIPs) for selective adsorption of ampicillin sodium were synthesized using surface molecular imprinting technique with silica gel as a support. The physical and morphological characteristics of the polymers were investigated by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), elemental analysis and nitrogen adsorption–desorption test. The obtained results showed that the SMIPs displayed great adsorption capacity (13.5μg/mg), high recognition ability (the imprinted factor is 3.2) and good binding kinetics for ampicillin sodium. Finally, as solid phase extraction adsorbents, the SMIPs coupled with HPLC method were validated and applied for the enrichment, purification and determination of ampicillin sodium in real milk and blood samples. The averages of spiked accuracy ranged from 92.1% to 107.6%. The relative standard deviations of intra- and inter-day precisions were less than 4.6%. This study provides a new and promising method for enriching, extracting and determining ampicillin sodium in complex biological samples.

Determination of ractopamine in pork using a magnetic molecularly imprinted polymer as adsorbent followed by HPLC

A new magnetic molecularly imprinted polymers (MMIPs) for separation and concentration of ractopamine (RAC) were prepared using surface molecular imprinting technique with methacryloyl chloride as functional monomer and RAC as template. The MMIPs were characterized using transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and vibrating sample magnetometer. The results of re-binding experiments indicated that the MMIPs had fast adsorption kinetics and could reach binding equilibrium within 20min, and the adsorption capacity of the MMIPs was 2.87-fold higher than that of the corresponding non-imprinted polymer. The selectivity of the MMIPs was evaluated according to its recognition to RAC and its analogues. The synthesized MMIPs were successfully applied to extraction, followed by high performance liquid chromatography to determine RAC in real food samples. Spiked recoveries ranged from 73.60% to 94.5%, with relative standard deviations of <11.17%.

Preparation of molecularly imprinted polymers using theanine as dummy template and its application as SPE sorbent for the determination of eighteen amino acids in tobacco

In this paper, a novel dummy template molecularly imprinted polymer (DMIP) based on a vinyl-SiO2 microspheres surface for the simultaneous selective recognition and enrichment of 18 amino acids was prepared via a surface molecular imprinting technique using theanine as a dummy template. Compared to the imprinted polymers prepared using traditional polymerization techniques, the obtained DMIPs exhibited a regular spherical shape and were relatively monodisperse. The maximal sorption capacity (Qmax) of the resulting DMIPs for the 18 amino acids was up to 1444.3mgg−1. A kinetic binding study showed that the sorption capacity reached 85.40% of Qmax in 25min and sorption equilibrium at 30min. The imprint factors of the sorbents ranged from 2.86 to 6.9 for the 18 amino acids, which indicated that the DMIP sorbents have high selectivity. An HPLC-UV method for the simultaneous determination of 18 amino acids in tobacco and tobacco smoke was developed using the DMIPs as sorbents for solid phase extraction (SPE) in the sample pretreatment procedure. Under the optimum experimental conditions, the materials had enrichment factors of up to 200 for the amino acids, and the recoveries of the 18 amino acids in tobacco smoke were in the range from 79% to 104% with relative standard deviations of less than 7.4%. It indicated that the obtained DMIP sorbents could specifically recognize the amino acids from complicated samples.

Core–Shell Magnetic Molecularly Imprinted Polymer Prepared for Selectively Removed Indole from Fuel Oil

ABSTRACTMagnetic molecularly imprinted polymers (MMIPs) were synthesized for selective recognition and rapid enrichment of indole from a model fuel. The MMIPs were synthesized by precipitation polymerization and a surface molecular imprinting technique, using indole as the template molecule, Fe3O4 nanoparticles as magnetically susceptible components, methylacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as a cross‐linker. The properties of the MMIPs were characterized by Fourier‐transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, and thermogravimetric analysis. The adsorption capacity of indole–molecularly imprinted polymers (MIPs) was 50.25 mg g−1 at 303 K and reached adsorption equilibrium in a short time. Experimental data were modeled with a pseudo–second‐order, Langmuir isotherm model. The selective adsorption performance of MIPs was favorable.

A highly-efficient imprinted magnetic nanoparticle for selective separation and detection of 17β-estradiol in milk

In this work, we prepared molecularly imprinted polymers (MIPs) combining surface molecular imprinting technique and magnetic separation for separation and determination of 17β-estradiol (E2) from milk. During the synthesis process, the acryloyl chloride was specially used to graft double bonds on Fe3O4 nanoparticles and served as co-functional monomer cooperating with acrylamide. The morphology, structure property, and the best polymerization and adsorption conditions of the prepared magnetic nanoparticles were investigated in detail. The obtained nanomaterials displayed high adsorption capacity of 12.62mg/g, fast equilibrium time of 10min, and satisfactory selectivity for target molecule. What’s more, the MIPs was successfully applied as sorbents to specifically separate and enrich E2 from milk with a relatively high recovery (88.9–92.1%), demonstrating the potential application of the MIPs as solid phase extractant for rapid, highly-efficient, and cost-effective sample analysis.

Synthesis and Recognition of Nano Pore Molecularly Imprinted Polymers of Thymol on the Surface of Modified Silica Nanoparticles

ABSTRACTTo the best of our knowledge, for the first time in this study, nano pore molecularly imprinted polymers were prepared using thymol as a template. A molecularly imprinting polymer with high performance for recognizing thymol was prepared by a novel surface molecular imprinting technique. First, silica nanoparticles were modified with γ‐methacyloxypropyl trimethoxysilane (KH‐570) as a support material. Afterward, surface molecularly imprinted polymers (SMIP) were obtained through polymerization with methacrylic acid as the functional monomer and trimethylolpropane trimethacrylate as the cross‐linking agent. The produced polymers were characterized by transmission electron microscopy, scanning electron microscopy, Brunauer–Emmett–Teller analysis as well as Fourier transform infrared spectroscopy. The SMIP were obtained with the average core shell thickness of 17 nm, an average pore diameter of 3.9 nm, and the high specific surface area of 282.3 m2 g−1. The adsorption properties were revealed by batch binding experiments. The results indicated that the SMIP had higher binding capacity for thymol than its nonimprinted polymers. The selectivity of the SMIP obtained was clarified by using thymol and structurally related compounds. The selectivity coefficient of SMIP for thymol with respect to competition species obtained was 2.44, which revealed SMIP had good selectivity and site accessibility for thymol. A kinetic binding study showed that adsorption capacity of SMIP increased continuously with time and reached saturation adsorption at 90 min.

Enhanced adsorption of norfloxacin on modified TiO2 particles prepared via surface molecular imprinting technique

For norfloxacin removal in aquatic environment, TiO2 particles (P25) were modified via surface molecular imprinting technique to improve the adsorption property and sustainable use by photocatalytic regeneration. Orthogonal experiment was adopted to quantify the significance of preparation factors and determine the optimum preparation conditions. The adsorption of norfloxacin on the molecular imprinted particles (MIPs), the non-imprinted particles (NIPs), and P25 fitted the second-order adsorption model and Langmuir model well. The MIPs showed a higher adsorption capacity toward norfloxacin than the NIPs and P25. The adsorption rate constant, maximum adsorption capacity, and Langmuir constant of the MIPs toward norfloxacin were 0.49g mg−1 min−1, 2.99 mg g−1, and 2.4 L mg−1, respectively. Removal efficiencies for norfloxacin, ciprofloxacin, carbamazepine, and phenol by the MIPs were 76.99, 78.81, 7.87, and 2.68%, respectively, which indicated that the MIPs had higher affinity toward norfloxacin and fluoroquinolones with similar structures. Moreover, the MIPs exhibited the photocatalytic property and could be regenerated by UV irradiation with stable removal efficiency for norfloxacin in five adsorption–regeneration cycles.

Surface molecularly imprinted silica for selective solid-phase extraction of biochanin A, daidzein and genistein from urine samples

Selective molecularly imprinted silica polymer (SiO2MIP) for extraction of biochanin A, daidzein and genistein was synthesized using the surface molecular imprinting technique with the silica gel as a support. Biochanin A (BCA) was used as a template, 3-aminopropyltriethoxysilane (APTES) as a functional monomer, and tetraethoxysilicane (TEOS) as a cross-linker. Non-imprinted polymer with the sol–gel process (SiO2NIP) was also prepared for comparison. The synthesized polymers were characterized by Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM) and a standard Brunauer-Emett-Teller (BET) and Barret–Joyner–Halenda (BJH) analysis. The obtained results indicated the structural differences between imprinted and non-imprinted polymers. Finally, the SiO2MIP and SiO2NIP were adopted as the adsorbents of solid phase extraction for isolation and preconcentration of biochanin A and its structural analogues–daidzein and genistein from aqueous and urine samples. The performance analysis revealed that SiO2MIP displayed better affinity to the three investigated isoflavones compared with SiO2NIP. The recoveries of spiked samples for studied analytes ranged from 65.7% to 102.6% for molecularly imprinted silica polymer and 8.9–16.0% for non-imprinted sorbents.

A novel reductive graphene oxide-based magnetic molecularly imprinted poly(ethylene-co-vinyl alcohol) polymers for the enrichment and determination of polychlorinated biphenyls in fish samples.

The novel reductive graphene oxide-based magnetic molecularly imprinted poly(ethylene-co-vinyl alcohol) polymers (rGO@m-MIPs) were successfully synthesized as adsorbents for six kinds of polychlorinated biphenyls (PCBs) in fish samples. rGO@m-MIPs was prepared by surface molecular imprinting technique. Besides, Fe3 O4 nanoparticles (NPs) were employed as magnetic supporters, and rGO@Fe3 O4 was in situ synthesis. Different from functional monomer and cross-linker in traditional molecularly imprinted polymer, here, 3,4-dichlorobenzidine was employed as dummy molecular and poly(ethylene-co-vinyl alcohol) was adopted as the imprinted polymers. After morphology and inner structure of the magnetic adsorbent were characterized, the adsorbent was employed for disperse solid phase extraction toward PCBs and exhibited great selectivity and high adsorption efficiency. This material was verified by determination of PCBs in fish samples combined with gas chromatography-mass spectrometry (GC-MS) method. According to the detection, the low detection limits (LODs) of PCBs were 0.0035-0.0070 µg l(-1) and spiked recoveries ranged between 79.90 and 94.23%. The prepared adsorbent can be renewable for at least 16 times and expected to be a new material for the enrichment and determination of PCBs from contaminated fish samples.

Development and characterization of magnetic molecularly imprinted polymers for the selective enrichment of endocrine disrupting chemicals in water and milk samples.

Analyses of four endocrine disrupting chemicals (EDCs) in water and milk samples were undertaken by using magnetic molecularly imprinted polymers (MMIPs). These were prepared via the surface molecular imprinting technique using super paramagnetic core-shell nanoparticle as support. Diethylstilbestrol (DES), which is a typical EDC, was employed as the template molecule. The obtained MMIPs were characterized using transmission electron microscope, Fourier transform infrared, X-ray diffraction, and vibrating sample magnetometer. Accordingly, the adsorption capacity and selectivity of prepared MMIPs were investigated. The binding isotherms were obtained for DES and fitted by the Freundlich isotherm model. A corresponding analytical method to determine four EDCs was developed. The recoveries of the spiked samples in pond water and pure milk range from 67.8 to 93.2% and from 65.3 to 92.5%, respectively. Coupled with high-performance liquid chromatography analysis, the prepared MMIPs were successfully applied to the analysis of EDCs in water and milk samples.

Preparation of magnetic molecularly imprinted polymers for selective isolation and determination of kaempferol and protoapigenone in Macrothelypteris torresiana.

Novel uniform-sized magnetic molecularly imprinted polymers (MMIPs) were synthesized for selective recognition of active antitumor ingredients of kaempferol (KMF) and protoapigenone (PA) in Macrothelypteris torresiana (M. torresiana) by surface molecular imprinting technique in this study. Super paramagnetic core-shell nanoparticles (γ-MPS-SiO2@Fe3O4) were used as seeds, KMF as template molecule, acrylamide (AM) as functional monomer, and N, N'-methylene bisacrylamide (BisAM) as cross-linker. The prepared MMIPs were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), transmission electron microscopy (TEM) and thermo-gravimetric analysis (TGA), respectively. The recognition capacity of MMIPs was 2.436 times of non-imprinted polymers. The adsorption results based on kinetics and isotherm analysis were in accordance with the pseudo-second-order model (R (2)=0.9980) and the Langmuir adsorption model (R (2)=0.9944). The value of E (6.742 kJ/mol) calculated from the Dubinin-Radushkevich isotherm model suggested that the physical adsorption via hydrogen-bonding might be predominant. The Scatchard plot showed a single line (R (2)=0.9172) and demonstrated the homogeneous recognition sites on MMIPs for KMF. The magnetic solid phase extraction (MSPE) based on MMIPs as sorbent was established for fast and selective enrichment of KMF and its structural analogue PA from the crude extract of M. torresiana and then KMF and PA were detected by HPLC-UV. The established method showed good performance and satisfactory results for real sample analysis. It also showed the feasibility of MMIPs for selective recognition of active structural analogues from complex herbal extracts.

Molecularly imprinted polymers based on SBA-15 for selective solid-phase extraction of baicalein from plasma samples.

Highly selective molecularly imprinted mesoporous silica polymer (SBA-15@MIP) for baicalein (BAI) extraction was synthesized using a surface molecular imprinting technique on the SBA-15 supporter. Computational simulation was used to predict the optimal functional monomer for the rational design of SBA-15@MIP. Meanwhile, high adsorption capacity was obtained when a suitable yield of molecularly imprinted polymers (MIPs) layer wasgrafted onto the surface of SBA-15. Characterization and performance tests of the obtained polymer revealed that SBA-15@MIP possessed a highly ordered mesoporous structure, reached saturated adsorption within 60min, and exhibited higher sorption capacity to the target molecule BAI compared with non-imprinted mesoporous silica polymer (SBA-15@NIP) and SBA-15. Finally, SBA-15@MIP was successfully applied to solid-phase extraction (SPE) coupled with high-performance liquid chromatography and ultraviolet detection (HPLC-UV) for the determination of trace BAI in plasma samples. Mean recoveries of BAI through the molecularly imprinted solid-phase extraction(MISPE) sorbent, non-imprinted solid-phase extraction(NISPE) sorbent, and SBA-15 solid-phase extraction (SBA-15-SPE) sorbent were 94.4, 22.7, and 10.7%, respectively, and the relative standard deviations were 2.9, 2.6, and 3.6%, respectively. These results reveal that SBA-15@MIP as a SPE sorbent has good applicability to selectively separate and enrich trace BAI from complex samples.

RETRACTED: Imprinted ZnO nanostructure-based electrochemical sensing of calcitonin: A clinical marker for medullary thyroid carcinoma

The present work describes an exciting method for the selective and sensitive determination of calcitonin in human blood serum samples. Adopting the surface molecular imprinting technique, a calcitonin-imprinted polymer was prepared on the surface of the zinc oxide nanostructure. Firstly, a biocompatible tyrosine derivative as a monomer was grafted onto the surface of zinc oxide nanostructure followed by their polymerization on vinyl functionalized electrode surface by activator regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP) technique. Such sensor can predict the small change in the concentration of calcitonin in the human body and it may also consider to be as cost-effective, renewable, disposable, and reliable for clinical studies having no such cross-reactivity and matrix effect from real samples. The morphologies and properties of the proposed sensor were characterized by scanning electron microscopy, cyclic voltammetry, difference pulse voltammetry and chronocoulometry. The linear working range was found to be 9.99 ng L(-1) to 7.919 mg L(-1) and the detection limit as low as 3.09±0.01 ng L(-1) (standard deviation for three replicate measurements) (S/N=3).

A highly selective photoelectrochemical biosensor for uric acid based on core–shell Fe3O4@C nanoparticle and molecularly imprinted TiO2

Combining the surface modification and molecular imprinting technique, a novel photoelectrochemical sensing platform with excellent photochemical catalysis and molecular recognition capabilities was established for the detection of uric acid based on the magnetic immobilization of Fe3O4@C nanoparticles onto magnetic glassy carbon electrode (MGCE) and modification of molecularly imprinted TiO2 film on Fe3O4@C. The developed biosensor was highly sensitive to uric acid in solutions, with a linear range from 0.3 to 34µM and a limit of detection of 0.02μM. Furthermore, the biosensor exhibited outstanding selectivity while used in coexisting systems containing various interferents with high concentration. The practical application of the biosensor was also realized for the selective detection of uric acid in spiked samples. The study made a successful attempt in the development of highly selective and sensitive photoelectrochemical biosensor for urine monitoring.

A core-shell surface magnetic molecularly imprinted polymers with fluorescence for λ-cyhalothrin selective recognition.

In this study, we report here a general protocol for making core-shell magnetic Fe3O4/SiO2-MPS/MIPs (MPS = 3-(methacryloxyl) propyl trimethoxysilane, MIPs = molecularly imprinted polymers, Fe3O4/SiO2-MPS as core, MIPs as shell) viaa surface molecular imprinting technique for optical detection of trace λ-cyhalothrin. The fluorescent molecularly imprinted polymer shell was first prepared by copolymerization of acrylamide with a small quantity of allyl fluorescein in the presence of λ-cyhalothrin to form recognition sites without doping. The magnetic Fe3O4/SiO2-MPS/MIPs exhibited paramagnetism, high fluorescence intensity, and highly selective recognition. Using fluorescence quenching as a detecting tool, Fe3O4/SiO2-MPS/MIPs were successfully applied to selectively and sensitively detect λ-cyhalothrin, and a linear relationship could be obtained covering a wide concentration range of 0-50 nM with a correlation coefficient of 0.9962 described by the Stern-Volmer equation. The experimental results of practical detection revealed that magnetic Fe3O4/SiO2-MPS/MIPs as an attractive recognition element was satisfactory for determination of trace λ-cyhalothrin in honey samples. This study, therefore, demonstrated the potential of MIPs for detection of λ-cyhalothrin in food.

Adsorption and recognition characteristics of surface molecularly imprinted polymethacrylic acid/silica toward genistein

In this paper, on the basis of surface-initiated graft polymerization, a new surface molecular imprinting technique is established by molecular design. And molecularly imprinted polymer MIP-PMAA/SiO2 is successfully prepared with genistein as template. The adsorption and recognition characteristics of MIP-PMAA/SiO2 for genistein are studied in depth by using static method, dynamic method and competitive adsorption experiment. The experimental results show that MIP-PMAA/SiO2 possesses very strong adsorption affinity and specific recognition for genistein. The saturated adsorption capacity could reach to 0.36mmolg−1. The selectivity coefficients relative to quercetin and rutin are 5.4 and 11.8, respectively. Besides, MIP-PMAA/SiO2 is regenerated easily and exhibits excellent reusability.

A New Molecularly Imprinted Polymer Prepared by Surface Imprinting Technique for Selective Adsorption towards Rhodamine B

A new molecularly imprinted polymers (Rhodamine B-KH-570/SiO2,MIPS) with high performance for recognizing Rhodamine B was prepared by adopting the surface molecular imprinting technique with silica-gel modified by KH-570 as a carrier material, acrylamide as the functional monomer and N,N-methylene-bis-acrylamide (MBA) as the crosslinker.The static adsorption experiments indicated that MIPS had significantly higher adsorption capacity for Rhodamine B than its non-imprinted polymers (NIPS). Dynamic binding study showed that the MIPS had good site accessibility and mass transport for Rhodamine B.Scatchard analysis revealed that two classes of binding sites were formed in MIPS with dissociation constants of 0.086mol/L and 0.0076 mol/L, and the maximum apparent binding capacity was 96.00μmol/g and 50.07 μmol/g, respectively.The selectivity coefficients and separation factors of MIPS for Rhodamine B in relation to competition species Rhodamine123 were 131.51 and 3.86 respectively, which suggested that MIPS had high recognition selectivity and binding affinity for the template molecule Rhodamine B.

Photoelectrochemical bilirubin biosensor based on Fe3O4/hydroxyapatite/molecularly imprinted polypyrrole nanoparticles

Magnetic Fe3O4/hydroxyapatite/molecularly imprinted polypyrrole (Fe3O4/HAP/MIPPy) nanoparticles with molecularly recognitive photoactivity were successfully prepared via the surface modification and molecular imprinting technique. A novel photoelectrochemical bilirubin biosensor was fabricated by conveniently attaching the proposed Fe3O4/HAP/MIPPy nanoparticles to the surface of the magnetic glassy carbon electrode (MGCE). The developed biosensor was highly sensitive to bilirubin in solutions, with a linear range from 0.1 to 17μM and a limit of detection of 0.007μM. Moreover, the biosensor exhibited outstanding selectivity while used in coexisting systems containing various interferents with high concentration. The favorable performance of the obtained bilirubin biosensor can be mainly attributed to high photoelectric activity, large surface-to-volume ratio, fast electron transfer and selective recognition of Fe3O4/HAP/MIPPy nanoparticles. The analytical application of the photoelectrochemical bilirubin biosensor confirms the feasibility of bilirubin detection in serum sample.

Selective adsorption and degradation of rhodamine B with modified titanium dioxide photocatalyst

ABSTRACTA new highly selective photocatalyst (RhB‐MIP/TiO2) was successfully prepared by surface molecular imprinting technique using rhodamine B (RhB) as template molecule. The adsorption kinetics show RhB‐MIP/TiO2 possessed fast adsorption rate, and adsorption behavior followed the pseudo‐second‐order kinetics. The static binding experiments revealed RhB‐MIP/TiO2 displayed strong affinity and high adsorption capacity for RhB. Moreover, the equilibrium adsorption rate of RhB‐MIP/TiO2 for RhB can be well fitted by the Langmuir isotherm model. The thermodynamics parameters indicated that the binding system of RhB‐MIP/TiO2 was endothermic and spontaneous. Compared with non‐imprinted photocatalyst (NIP/TiO2), RhB‐MIP/TiO2 exhibited excellent selectivity toward RhB, whose selectivity coefficient for RhB relative to rhodamine 6G (Rh6G) was 2.99. Selective photocatalytic degradation experiments indicated that the apparent rate constant for the photodegradation of RhB over RhB‐MIP/TiO2 is 0.0212 min−1, being 216% of that over NIP/TiO2 (0.0098 min−1). Therefore, RhB‐MIP/TiO2 exhibited higher photocatalytic selectivity toward RhB. The prepared photocatalyst RhB‐MIP/TiO2 has a promising perspective in industrial wastewater treatment. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40890.

Magnetic dummy molecularly imprinted polymers based on multi-walled carbon nanotubes for rapid selective solid-phase extraction of 4-nonylphenol in aqueous samples

In this paper, a highly selective sample clean-up procedure combining magnetic dummy molecular imprinting with solid-phase extraction was developed for rapid separation and determination of 4-nonylphenol (NP) in the environmental water samples. The magnetic dummy molecularly imprinted polymers (mag-DMIPs) based on multi-walled carbon nanotubes were successfully synthesized with a surface molecular imprinting technique using 4-tert-octylphenol as the dummy template and tetraethylorthosilicate as the cross-linker. The maximum adsorption capacity of the mag-DMIPs for NP was 52.4mgg−1 and it took about 20min to achieve the adsorption equilibrium. The mag-DMIPs exhibited the specific selective adsorption toward NP. Coupled with high performance liquid chromatography analysis, the mag-DMIPs were used to extract solid-phase and detect NP in real water samples successfully with the recoveries of 88.6–98.1%.