Papers by Keyword: Molecular Imprinting

Abstract: In order to selectively separate luteolin from its crude solution, we synthesized luteolin molecular imprinted polymers (LMIP) with high recognition specificity for luteolin, using an imprinting technique. Luteolin was used as template, methanol as solvent, and N,N’-methylenebisacrylamide (MBAA) as the cross-linking. Then prepared LMIP were characterized and evaluated by scanning electron microscope (SEM) and equilibrium absorption experiments. The results showed that the cavities matching with the template molecules in size and structure were present in the LMIP. Adsorption dynamics analysis suggested that, when the adsorption time reached 4 h, the adsorption process had reached balance and the adsorption capacity was at steady state. The selective adsorption amount reached at 35.65 umol/g for the LMIP, while a lower value of 11.68 umol/g for the blank polymer (i.e. nontemplated). Relative to the corresponding blank polymer, LMIP had an excellent recognition to luteolin in methanol solution. Keywords: Molecular imprinting, Molecular recognition, Adsorbent, Luteolin

Abstract: Molecular imprinting is a technique to produce a polymer called as molecularly imprinted polymer (MIP) that provides cavities to form a particular space generated by removing the template when the polymer has been formed. It will recognize a target that has the shape and physico-chemical properties similar or identical with those of template molecule. In this study, MIPs using atrazine as template have been made via the cooling-heating method. Initially the pre-polymer solution was cooled at a refrigerator for 1 h. Next, the polymerization was carried out at 70 °C for heating times of 90, 120, and 150 min. without nitrogen flow which is generally done for polymerization process. Characterizations were performed by employing a reversed-phase high performance liquid chromatograph (HPLC) and scanning electron microscope (SEM). From Scatchard plots, it was found that the equilibrium dissociation constant K_D and the apparent maximum number of binding sites B_max, which are written as (K_D, B_max), are (4.69 μM, 9.87 mmol/g), (4.54 μM, 9.56 mmol/g) and (3.52 μM, 7.44 mmol/g) for the heating times of 150, 120, and 90 min., respectively. This is verified by their SEM images showing that the broadest pore size distribution with the highest number of pores is in the MIP prepared under the heating time of 150 min. The MIPs therefore could be applied as an atrazine sensor and the MIP prepared under the heating time of 150 min. would give its best characteristics compared to the others.

Abstract: To separate and enrich morin, a molecularly imprinted polymer (MIP) was synthesized on chitosan by surface molecular imprinting technique and characterized with Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The results showed that MIP possessed better selectivity and recognition for morin in a mixture than that of non-imprinted polymer (NIP). The saturated adsorption amount of MIP was 8.0 mg/g, which was 4-fold than that of NIP, and the recovery in the elution step was 94.87% and 10.97% for MIP and NIP, respectively. These findings indicate MIP could realize the separation and pre-concentration of morin in real sample and may be used for solid phase extraction (MIP-SPE) protocol.

Abstract: This article gives a contrast of molecular imprinting affinity purification method (by HPLC) and immunoaffinity column purification method (by HPLC) in the determination of zearalenone in corn. In the determination process, two levels (dosages) of 60μg/kg and 500μg/kg were used. Recoveries of by means of the two methods were 90.4%, 90.1% and 92.9%, 90.7% respectively. And the molecular imprinting affinity column can be reused several times.

Abstract: A simple and efficient molecularly imprinted sensor (MIPs/GR/GCE) was firstly prepared by electropolymerization of pyrrole in the presence of bovine serum albumin (BSA) in an aqueous solution based on a graphene modified glassy carbon electrode for the selective recognition of bovine serum albumin. The prepared sensor was characterized by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS), in which [Fe(CN)₆]³⁻/⁴⁻ was used as an electrochemical active probe. The results showed a wide linear range from 1.0 × 10^-3 to 1.0 × 10^-9 g/mL. And the imprinted biosensor indicated excellent selectivity and high sensitivity.

Abstract: Quercetin is a flavonoid present in herbs, fruits and vegetables. It acts as an antioxidant, anticancer and anti-inflammatory agent. Molecularly Imprinted Polymers (MIPs) were prepared for quercetin by non-covalent approach in the presence of monomer acrylamide, EGDMA as the crosslinker, AIBN as the initiator and methanol and ethyl acetate as porogenic solvents. Most stable MIPs were synthesized using methanol as the solvent. Step wise removal of the template with methanol and acetic acid (9:1) left binding sites that retain complementary specificity and affinity. These stable MIPs were analysed by FT-IR technique. It was observed that there was hydrogen bonding between the template and the functional monomer. This study was further supported by NMR analysis for MIPs and NMIPs (control polymer) that cavity for quercetin has been created in MIPs and absent in the case of NMIPs. MIPs were characterized by SEM analysis that showed more clusters in case of MIPs than NMIPs as an effect of imprinting. These MIPs can be used for extraction of quercetin from herbs in a one step process.

Abstract: Research has been focused on the development of molecularly imprinted polymers using a chitosan derivative as the precursor. An O-acyl chitosan was synthesized by the selective protection of amino groups of chitosan in MeSO₃H and was cross-linked with glutaraldehyde in the presence/ absence of template molecule, cholesterol. The effect of the degree of the acyl substitution on the selection of precursor was investigated, regarding the solubility of chitosan derivative, interaction between the precursor and imprinted molecule, and degree of the cross-linking of precursor. The rebinding experiments indicated the significant recognition for cholesterol with imprinted polymer as compared with non-imprinted polymer. It was found that a good binding capacity of the imprinted polymer towards cholesterol could be achieved in a less-polar solvent. And the O-acyl chitosan-based molecularly imprinted polymer obtained displayed good recognition selectivity for cholesterol in comparison to similarly strctural analogue, cholesterol acetate.

Abstract: In order to indomethacin (IDM) for imprinting molecular, acrylamide (AA) as functional monomer, ethylene glycol dimethacrylate (EGDMA two) as crosslinking agent, respectively by photopolymerization and thermal polymerization of two methods of aqueous solution polymerization, suspension polymerization preparation of molecularly imprinted polymer.The polymer adsorption experiments show that the use of light-polymerized specificity is strong; light initiated polymer used for sample determination and calibration experiments, results in tap water and river water samples in Enshi Qingjiang indomethacin recoveries were 84.3% and 87.1%, were higher than 80%.Tap water and the relative standard deviation (n = 3) were 3.96%, 14.2%, that can be used for the separation and enrichment of indomethacin in water samples.

Abstract: Molecular imprinting is a technique to prepare polymers with predetermined selectivity, specific recognition and predesigned affinity to a desired molecule. The stability and low cost of molecularly imprinted polymers (MIPs) render them attractive for a broad range of applications. Currently, MIP technique has been widely used in chiral separation. In this study, a series of molecularly imprinted polymers for N-Carbobenzoxy-L-tryptophan (N-Cbz-L-Trp) synthesized in different conditions were prepared in a small scale to simulate the monolithic chiral stationary phases (CSPs) primarily. By coupling in situ processing and batch rebinding evaluation, the type of functional monomers, which likely to affect the chiral selectivity of MIPs, was investigated. It was found that a MIP comprising a mixture of functional monomer 4-vinylpyridine (4-VP) and porogen 1-dodecanol/toluene exhibited the highest binding capacity and chiral selectivity for N-Carbobenzoxy-L-tryptophan. Thereafter, the monolithic MIP synthesized in screened optimum condition is used as chiral stationary phase in HPLC, which shows favourable separating capacity.

Abstract: A novel sensing element for direct detection of L-Tryptophan (L-Trp) in human serum was proposed by combination of electrochemical transduction and molecular imprinting technique. The sensing element was prepared by electropolymerization of o-phenylenediamine (o-PD) on the gold electrode in the presence of template L-Trp. The electrochemical property of the sensor was characterized by differential pulse voltammetry (DPV). The linear response range of the sensor for L-Trp concentration was 1×10^-8 mol/L~21×10^-8 mol/L with a detection limit of 0.3×10^-8 mol/L. The results show that this approach has the potential to generate a universal inexpensive assay methodology of high sensitivity, specificity and simplicity to detect L-Trp.