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Vanillic acid (4-hydroxy-3-methoxybenzoic acid) is a phenolic acid found in many plant extracts. It is used as aflavoring and scent agent and produces a pleasant, creamy odor. It is widely used in many applications for therapeuticpurposes to flavoring agent. Molecularly imprinted polymers of vanillic acid were synthesized by precipitationpolymerization with a noncovalent approach for the extraction from blood serum. Three different imprinted polymershave been synthesized with varying molar ratio of monomer. The synthesized polymer particles were characterizedusing Fourier-transform infrared spectroscopy and scanning electron microscopy. The extraction efficiency of highlyselected imprinted polymer of vanillic acid from spiked blood serum was about 80%.
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Objective: The molecularly imprinted osthole on surface-modified quartz sand was prepared and characterized by SEM and FT-IR. The adsorption properties of molecularly imprinted materials were investigated. Methods: The morphology of MIP was prepared using N-(β-aminoethyl)-γ-aminopropylmethylbimethoxy silane (KH-602) modified quartz sand as supporter, osthole as template, methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as crosslinker, axodiisobutyronitrile (AIBN) as initiator, and methanol as porogen, observed by SEM, and the chemical structure of MIP was characterized by FT-IR. Results: The dynamic adsorption experiment showed that the adsorption capacity of molecularly imprinted materials to osthole gradually reached saturation with the increase of time. The maximum adsorption capacity of molecularly imprinted materials for osthole was studied by static adsorption experiment. The selective adsorption experiment was adopted to study the binding properties and molecule recognition characters of molecularly imprinted materials for osthole. Conclusion: The experimental results showed that MIP had specific recognition selectivity, excellent binding affinity and elution property for ractopamine. The MIP on the adsorption ability of osthole was significantly better than xanthotoxin and imperatorin.
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Objective To prepare surface molecular imprinted polymers (MIP) of galangin by using surface molecular imprinting technique. Methods Galangin MIP was prepared by surface polymerization method at the surface of silica gel, which was modified with (3-aminopropyl) trimethoxysilane, by using galangin as the template molecule, methacrylic acid (MAA) as the functional monomer, and N,N′-methylenebisacrylamide (MBA) as crosslinking agent. The polymer was characterized by infrared spectroscopy and scanning electron microscopy. And its adsorption properties were studied by static and competitive adsorption method. Results The experimental research showed that the optimal preparation condition was that the molar ration of galangin to MAA was 1∶4, with molar ration of MAA to MBA 1∶7, reaction temperature 40 ℃ and reaction time 12 h. Infrared spectrum and scanning electron microscopy showed that MIP was successfully grafted on the surface of silica gel, and recognition holes and sites selectively appeared for galangin molecules. Adsorption experiments exhibited that MIP had specific recognition and good affinity for galangin molecules. Compared to the controls of breviscapine and luteolin, the selectivity coefficients of MIP to galangin were 11.2 and 5.3, respectively. Conclusion MIP has good recognition and high selectivity for galangin, which provides a new method for the separation and extraction of flavonoids from Chinese medicine.
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OBJECTIVE:To synthesize 4-hydroxyphenylacetic acid(PHPAA)molecular imprinted polymers(MIPs),and to provide reference for separation and enrichment of PHPAA in urine of cancer patients. METHODS:With PHPAA as template molecule and azobisisobutyronitrile as evocating agent,MIPs was synthesized by precipitation polymerization using 4-vinyl pyridine(4-V),acrylamide(AM),1-vinyl imidazole(1-V)and o-diaminobenzene as functional monomers,ethylene glycol dimethacrylate(EGDMA)and trimethylolpropane trimethacrylate(TRIM)as crosslinking agent. Using scanning electron microscope,infrared spectrum,static adsorption test and molecular recognition performance test used adopted to characterize the structure and performance of MIPs. RESULTS:MIPs1(4-V,EGDMA)microspheres adhered seriously,and MIPs2(AM, EGDMA)microspheres are aggregated. MIPs3(1-V,TRIM),MIPs4(o-diaminobenzene,TRIM)microspheresare were dispersed and had good sphericity. Characteristic absorption peak of PHPAA was not found in infrared spectrum of MIPs. The adsorption capacity of each MIPs was higher than that of blank imprinted polymer without the template molecule,and increased as the increase of template molecular concentration. The adsorption capacity of MIPs3 was significantly higher than that of other MIPs,and its static distribution coefficient(0.14)of PHPAA was higher than that of other structural analogues [PHPA(0.06),TA(0.01)],selective separation factors of PHPAA to PHPA,PHPAA to TA were 2.3,11.5,respectively. CONCLUSIONS:MIPs synthesized with 1-V as functional monomer and TRIM as crosslinking agent has the ability of specific adsorption and selective recognition. It can used as solid phase extractant to separate and enrich low content of PHPAA in the urine of tumor patients.
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Eighty percent of bacterial infections are related to the formation of bacterial biofilm. Compared with planktonic bacteria, bacterial biofilm is 10-1 000 times more resistant to antibiotics, which is the main cause of current bacterial drug resistance. A comprehensive understanding of the characteristics and resistance mechanisms of bacteria biofilm will help us treat the stubborn infections caused by the bacterial biofilm better and solve the problem of bacterial drug resistance. In this review, the composition and quorum sensing of bacterial biofilm, two major patterns of biofilm formation and drug resistance mechanisms were presented. Furthermore, representative compounds with anti-biofilm activity and compounds synergistic with antibiotics in anti-biofilm actions were introduced. Nano drug delivery strategies used for anti-biofilm in recent years as well as a novel drug delivery system-molecularly imprinted polymer was also introduced.
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AIM To establish a molecular imprinted polymers (MIPs)-HPLC method for the simultaneous content dertermination of four flavonoids in Rubus chingii Hu.METHODS Fe3O4 magnetic MIPs was added into ethyl acetate fraction solution of R.chingii to prepare mixed MIPs.The analysis of mixed MIPs methanol eluent was performed on a 30 ℃ thermostatic Diamonsil C18 column (250 mm ×4.6 mm,5 μm),with the mobile phase comprising of acetonitrile-0.1％ formic acid flowing at 1.0 mL/min in a gradient elution manner,and the detection wavelength was set at 266 nm.RESULTS Tannins,lilsonide,quercetin and kaempferol showed good linear relationships within the ranges of 2.4-1 232.0 μg (R2 =1)、7.1-3 648.0 μg (R2 =0.999 9)、4.7-4 840.0 μg (R2 =0.999 9)、4.8-2 440.0 μg (R2 =0.999 9),whose average recoveries were 98.94％,99.33％,99.26％ and 98.67％ with the RSDs of 2.04％,1.40％,1.76％ and 1.75％,respectively.CONCLUSION This accurate and reliable method eliminates impurity interference,which can be used for the content determination of flavonoids in R.chingii.
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AIM To establish a molecular imprinted polymers (MIPs)-HPLC method for the simultaneous content dertermination of four flavonoids in Rubus chingii Hu.METHODS Fe3O4 magnetic MIPs was added into ethyl acetate fraction solution of R.chingii to prepare mixed MIPs.The analysis of mixed MIPs methanol eluent was performed on a 30 ℃ thermostatic Diamonsil C18 column (250 mm ×4.6 mm,5 μm),with the mobile phase comprising of acetonitrile-0.1％ formic acid flowing at 1.0 mL/min in a gradient elution manner,and the detection wavelength was set at 266 nm.RESULTS Tannins,lilsonide,quercetin and kaempferol showed good linear relationships within the ranges of 2.4-1 232.0 μg (R2 =1)、7.1-3 648.0 μg (R2 =0.999 9)、4.7-4 840.0 μg (R2 =0.999 9)、4.8-2 440.0 μg (R2 =0.999 9),whose average recoveries were 98.94％,99.33％,99.26％ and 98.67％ with the RSDs of 2.04％,1.40％,1.76％ and 1.75％,respectively.CONCLUSION This accurate and reliable method eliminates impurity interference,which can be used for the content determination of flavonoids in R.chingii.
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Objective: To prepare rutin-Cu2+ complex imprinted polymer and study its adsorption ability. Methods: The polymer was prepared in mixed poler solvent, using α-methacrylic acid as functional monomer. The structure and preparation mechanism were studied by UV-vis spectroscopy and IR spectroscopy. Results: The polymer and rutin-Cu2+ complex were combined by coordinate bond and intermolecular force, the polymer had remarkably specific adsorption to complex of rutin-Cu2+. Conclusion: Rutin-Cu2+ complex molecularly imprinted polymer has great adsorption and specific identification to rutin-Cu2+, and can be used in extraction and separation of Chinese medicine effective constituent rutin.
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An electrochemical sensor has been developed for the selective determination of chlortetracycline ( CTC) using the molecularly imprinted technique. A molecular imprinted polymer ( MIP) on the surface of a glassy carbon electrode ( GCE ) was prepared by electropolymerization of o-aminophenol ( OAP ) in the presence of CTC in the sodium perchlorate ( NaClO4 ) solution using cyclic voltammetry ( CV ) . The electrochemical performance of the sensor was studied by using differential pulse voltammetry ( DPV ) . A linear relationship between the peak current difference and the CTC concentration was found in the range of 2. 0×10-8-6. 1×10-7 mol/L with the detection limit of 1. 5×10-8 mol/L (3σ). After regeneration by washing with the mixture of methanol and sulfuric acid, the sensor showed excellent reproducibility and good stability. The MIP electrode exhibited almost no response to chloramphenicol and penicillin, and very weak responses to tetracycline and oxytetracycline, proving a good selectivity. Recoveries of standard addition measured in the actual samples of milk and chicken meat were between 86 . 4% -96 . 9%. Compared with the reported methods, this sensor showed a low detection limit, simple operation without derivatization, rapid response and low cost.
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A molecularly imprinted electrochemiluminescence sensor for detection of cinchonine based on surface self-assembly of molecularly imprinted membrane on magnetic nanoparticles was developed. Cinchonine was used as template and lauryl mercaptan was used as assembling monomer. The morphology and particle size distribution of the magnetic nanoparticles were characterized by TEM, and the infrared spectroscopy was used to study the structure and composition of cinchonine, molecularly imprinted membrane before and after elution. The results showed that, cinchonine could be specifically assayed with a linear relationship between the signal intensity and the logarithm of concentrations of cinchonine in the range of 1×10-10 mol/L to 9×10-8 mol/L. The detection limit for cinchonine was 3. 5×10-11mol/L. The sensor was used for the determination of cinchonine in serum samples, with the recoveries of 98. 8% to 104. 7%.
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Paeoniflorin and its derivatives are main active compounds inGui-Zhi Fu-Ling Capsule (GZFLC). In this study, molecular imprinted polymer (MIP) was prepared by sol-gel process to obtain paeoniflorin and its derivatives in GZFLC. The static adsorption capacity of MIP was measured by scatchard equation. The results showed that the maximum apparent absorbing capacity of MIP was 52.28 mg·g-1. One-step separation of paeoniflorin from 4 g methanol samples of GZFLC was 197 mg with the purity of 89.3%. It was concluded that paeoniflorin MIP can be used to separate phaoniforin and its analogues from GZFLC.
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ThemagneticFe3O4nanoparticlesweresynthesizedbyco-precipitationmethod,andthenmagnetic Fe3 O4@Au nanoparticle was synthesized to improve the affinity of particle surface. L-Cys-GA3 was grafted on the surface of gold clad by self-assembly method, and then dropped it on glassy carbon electrode, for further manufacture of MIP/Fe3 O4@Au by using electropolymerzation L-Cys. The surface morphology and particle size distribution of Fe3 O4@Au were studied by TEM. The structure and composition of gibberellins A3, MIP and nMIP were studied by IR. The test system was optimized, and the results showed that when the cycles of electropolymerization was 30, acetic acid:methanol (1:8, V/V) was chosen as eluent, elution time was optimized for 5 min and rebinding time for 7 min, the sensor got a high stability and good recognition ability for gibberellins A3 . The concentration of gibberellins A3 in the range of 1 . 0 × 10-11-1 . 0 × 10-8 mol/L had a relationship with the oxidation peak current of probe, with the detection limit of 2. 57×10-12 mol/L. The sensor was successfully used for the determination of GA3 in beer sample.
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Objective: To investigate the specific molecular recognition ability for galangin molecular imprinting polymer (GMIP). Methods: GMIP was prepared through the method of thermal polymerization with galangin as template molecular, acrylamide (AM) as functional monomer, ethyleneglycol dimethacrylate (EGDMA) as cross-linker, and tetrahydrofuran, acetonitrile, and acetone as pore forming agents, respectively. The GMIP was characterized by infrared spectroscopy and scanning electron microscopy (SEM). In addition, the GMIP was investigated in equilibrium binding experiment to evaluate its adsorption property and selective recognition. Results: The Scathard model analysis showed that two kinds of binding sites existed in the GMIP. The dissociation constant (Kd) and apparent maximum binding constant (Qmax) were Kd1 = 0.961 mmol/L, Qmax1 = 19.79 μmol/g for high affinity binding sites and Kd2 = 0.101 mmol/L, Qmax2 = 51.09 μmol/g for low affinity binding sites, respectively. Conclusion: GMIP has the specific adsorption and recognition capabilities to the galangin molecules. It can be a novel material for the separation and purification of the active ingredients from natural products.
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Objective: To snythesize theophylline molecular imprinted polymer (MIP) microspheres. The influences of reaction conditions, including the category of solvent, reaction time, and the ratio of template to the cross-linking agent on the morphology and adsorption properties of MIP microspheres were studied. Methods: Theophylline MIP microspheres were prepared by precipitation polymerization with theophylline as template and ethyleneglycol dimethacrylate (EGDMA) as cross-linker. The microspheres were characterized by static adsorption and scanning electron microscopy (SEM). Results: The ratio of template to the cross-linking agent was 1:16, reaction time was 24 h, and acetontrile was the solvent. The theophylline MIP microspheres were regular microspheres. The MIP microspheres showed the high adsorption capacity and the partition coefficient of the microspheres adsorbing theophylline was 1.74. Conclusion: Theophylline MIP microspheres have the specific adsorption and recognition capabilities to the theophylline molecules.
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A method for the quantitative monitoring of sulfadiazine (SD) residues in pork was established by molecular imprinted column coupling with high performance liquid chromatography (HPLC).The molecular imprinted column was selected as an extraction device.To obtain the optimum extraction efficiency,several parameters related to the molecular imprinted column,including column solvent,flow-rate,eluent of the sample matrix and eluent volume,were investigated.The sample solution was directly injected into the device for the extraction after simple extraction.Under the optimum conditions,the relative standard deviations (RSD) was ≤6.1％ and the recoveries for SD were higher than 75.6％.In comparison with the AL-SPE column,the MIP-SPE column had good reusability and extraction efficiency.This method was successfully applied to the determination snlfadiazine residues in pork.
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Molecular imprinted film modified glassy carbon electrode was prepared by electrochemical polymerization of pyrrole with the cyclic voltammetry in the presence of template molecular, salicylic acid. The template molecules were removed from the modified electrode surface by over-oxidized at 1.3V in the solution of 0.2 mol/L Na2HPO4 for 10 min. The modified electrodes can effectively promote electrochemical oxidation process of salicylic acid in the surface of electrode and avoid interference of structural similar substance such as benzoic acid. Cyclic voltammetry was employed in the electrochemical measurements. The experimental results show that the optimum acidity of background solution is pH 6.86 and the optimum incubation is 10 min. The linear response curve was obtained from 1.0×10-6 mol/L to 2.0×10-3 mol/L, with the detection limit of 8.0×10-7 mol/L. The imprinted electrode has been applied to the analysis of salicylic acid in the simulated samples with recovery rates ranging from 94.6% to 103.4%.