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Antibiotics are a category of chemical compounds used to treat bacterial infections and are widely applied in cultivation,animal husbandry,aquaculture,and pharmacy.Currently,residual antibiotics and their metabolites pose a potential risk of allergic reactions,bacterial resistance,and increased cancer incidence.Residual antibiotics and the resulting bacterial antibiotic resistance have been recognized as a global challenge that has attracted increasing attention.Therefore,monitoring antibiotics is a critical way to limit the ecological risks from antibiotic pollution.Accordingly,it is desirable to devise new analytical platforms to achieve efficient antibiotic detection with excellent sensitivity and specificity.Quantum dots(QDs)are regarded as an ideal material for use in the development of antibiotic detection biosensors.In this review,we characterize different types of QDs,such as silicon,chalcogenide,carbon,and other doped QDs,and summarize the trends in QD-based antibiotic detection.QD-based sensing applications are classified according to their recognition strategies,including molecularly imprinted polymers(MIPs),aptamers,and immunosensors.We discuss the advantages of QD-derived antibiotic sensors,including low cost,good sensitivity,excellent stability,and fast response,and illustrate the current challenges in this field.
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In recent years, the overexpression dopamine (DA) due to the use of addictive drugs has caused concern and urgently needs to be addressed. The method used in our study is known as biomimetic sol-gel synthesis. We undertook the experiment to develop molecularly imprinted xerogel polymers (MIXPs) through template molecules dopamine polymerized with polyethyleneimine (PEI), then self-assembled and crosslinked with tetramethoxysilane (TMOS) in the form of non-covalent hydrogen bonds by using biomimetic sol-gel process, and then eluted template DA will leave a blotting site. Monoamine oxidase immobilized MIXPs (MAO-MIXPs) was obtained by coating monoamine oxidase onto MIXPs. The synthesis optimization of MAO-MIXPs was finally set as the ratio of DA template, PEI and MAO coating (DA 40 mg, PEI 0.6 mL, MAO 2.5 mg·g-1) to achieve highly selective adsorption toward DA in artificial cerebrospinal fluid based on the adsorption performance and degradation performance. The micromorphologies and physical-chemical properties of MAO-MIXPs were characterized by scanning electron microscopy, differential scanning calorimeter and Fourier transform infrared spectroscopy, and then amount of adsorption was calculated with adsorption equation. Simultaneously, the Brunner-Emmet-Teller (BET) and Langmuir model were simulated. It was found that the adsorption behavior tended to be monolayer adsorption. This new molecularly imprinted polymer demonstrated potential dopamine expression regulation for highly selective recognition, adsorption and degradation of dopamine.
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objective To develop a new method for the adsorption and separation of ginkgolic acid (GA). Methods Using salicylic acid (SA) as a dummy template and 4-vinylpyridine as the functional monomer, molecularly imprinted polymer (MIP) with high adsorbability to GA was synthesized by molecular self-assembly technique. The imprinting mechanism of the polymers was studied by 1H-NMR and IR spectra, and the structure of the polymers was characterized by SEM. The structure of the polymer was analyzed by FT-IR and the adsorption and binding properties of the polymer to total GA were analyzed by HPLC and UV detection. Results MIP had better three-dimensional space structure and adsorption properties. Template molecules were binded to functional monomers with noncovalent bonds. The adsorption rate of GA by polymer MIP in the extract of Ginkgo biloba was 95.9%. The Scatchard analysis reveals that there were two different recognition sites in MIP in the extract of G. biloba, and the apparent maximal combination amount (Qmax1) was 30 mg/g in high affinity recognition sites and with (Qmax2) = 80 mg/g in low affinity recognition sites. And the adsorption kinetics can be best described as the pseudo-second-order kinetics model. Conclusion The preparation of MIP with SA as dummy template has strong adsorption properties for GA, which has a good prospect of popularization and application in the separation and purification of GA.
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A molecular imprinting polymer technique was successfully applied to precipitation polymerization by using styrene as a functional monomer, curcuminoids as templates, acetonitrile as a porogenic solvent, benzoyl peroxide as the initiator, and ethylene glycol dimethacrylate as the crosslinker. The effects of interaction on the adsorption capacity of the molecularly imprinted polymer (MIP) and non-imprinted polymer (NIP) were investigated. A comparison of the adsorption capacity for MIP and NIP indicated that the NIP had the lowest adsorption capacity. The curcuminoid-imprinted polymer (Cur-MIP) was syn-thesized from 0.0237 mmol of styrene, 47.0 g of acetonitrile, 1.0238 mmol of ethylene glycol dimetha-crylate, 0.0325 mmol of curcuminoids, and 0.2480 mmol of benzoyl peroxide. A high-performance liquid chromatography method with fluorescence detection was developed and validated for various chro-matographic conditions for the determination of the curcuminoids in turmeric samples. The sample solution was separated using the Cur-MIP via solid-phase extraction and analyzed on a Brownlee ana-lytical C18 column (150 mm × 6 mm, 5μm) using an isocratic elution consisting of acetonitrile and 0.1%trichloroacetic acid (40:60, v/v). The flow rate was maintained at 1.5 mL/min. The fluorescence detector was set to monitor atλex = 426 nm andλem = 539 nm. The quantification limit values were found to be 16.66, 66.66, and 33.33μg/L for curcumin, demethoxycurcumin, and bisdemethoxycurcumin, respec-tively. Thus, we concluded that the Cur-MIP and high-performance liquid chromatographic-fluorescence method could be applied to selective extraction and could be used as a rapid tool for the determination of curcuminoids in medicinal herbal extracts.
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Objective To develop a novel strategy for separation and purification of target protein by magnetic molecularly imprinted nanoparticles . Methods Fe3 O4 nanoparticles were synthesized through a hydrothermal method .A sol-gel technique was adopted to prepare imprinting layers .The adsorption capability of magnetic molecularly imprinted nanoparticles was investigated by kinetic , isothermal , and selective binding experiments .Results The imprinted nanomaterials could reach equilibrium within 30 min . The adsorption capacity was 44 .51 mg/g .The imprinting factor and selectivity coefficient were 3 .50 and 2 .92 ,respectively .The resulting imprinted polymers could selectively separate and enrich bovine hemoglobin from a bovine blood sample . Conclusion The prepared imprinted nanomaterials with good specific adsoprtion ability can provide an effective strategy for separation and purification of target protein .
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Molecular simulation was used to study the interaction between template molecule and functional monomer to shorten the optimization time for the functional monomer and the ratio of functional monomer and template molecule.Kaempferol molecularly imprinted polymerization (MIP) monolithic column was therefore synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization with dibenzyltrithiocarbonate (DBTTC) and ethyleneglycoldim ethacrylate (EDMA) as RAFT and cross-linking agent, respectively, whereas methacrylic acid (MAA) was the optimal functional monomer with the molar ratio of kaempferol/MAA of 1∶4 from molecular simulation results.The results indicate that molecular simulation is useful to simplify the experimental procedure, and DBTTC as RAFT agent can provide more adjustable and better MIP monolithic column.
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The magnetic molecularly imprinted polymers (MMIPs), based on the surface of magnetic nanoparticles being modified by surface grafting, have been successfully synthesized, with dibutyl phthalate (DBP) as template molecule, ethylene glycol dimethacrylate (EGDMA) as cross-linking agent and azobisisobutyronitrile (AIBN) as initiator. Scanning electron microscopy (SEM), transmission electron microscope (TEM), and elemental analysis were employed to characterize the MMIPs. The structure and magnetic properties of the MMIPs were investigated by means of X-ray diffraction and vibrating sample magnetometer. The BET surface area shows that MMIPs is 380 m2/g and MNIPs is 324 m2/g. A series of static adsorption experiments were conducted to analyze its adsorption performance, which followed pseudo-second-order model by the kinetic analysis with correlation coefficient (R2) 0.9797, and Sips equation with correlation coefficient (R2) 0.999 by the isothermal analysis. The imprinting factors of diallyl phthalate (DAP), DBP and di-2-ethylhexyl phthalate (DEHP) were 1.53, 2.21 and 1.39 respectively, showing that MMIPs had better recognition performance for DBP. The experiment of regeneration recycles with five times showed the regeneration ability of DBP was only reduced by 12.3％.
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To improve the sensitivity of molecularly imprinted electrochemical sensors, a Pd nanoparticles-modified molecularly imprinted polymer (MIP) film for the determination of trimethoprim (TMP) was developed by thermal polymerization with N, N′-methylene diacrylamide as a functional monomer, Pd nanoparticle as a dopant and ethylene glycol maleic rosinate acrylate as a crosslinking agent.The morphologies and chemical structures of the Pd nano-materials and the imprinted films were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy, respectively.The electrochemical properties of the nano-doped and undoped MIP sensors were investigated by cyclic voltammetry and electrochemical impedance spectroscopy.Results showed that the morphologies and chemical structures and the electrochemical properties of the doped molecularly imprinted sensor were remarkably different from those of the undoped imprinted sensor.Linear responses of the imprinted sensor to TMP were observed for concentrations ranging from 5.0×10-7 mol/L to 4.0×10-3 mol/L (R=0.9995), with a detection limit of 3.2×10-8 mol/L (S/N=3).The Pd nanoparticle doped MIP sensors exhibited high selectivity.The chronoamperometry showed that no interference from potential interfering species such as sulfamethoxazole, sulfadiazine, glucose, and urea were noted.The proposed electrochemical sensor was used to determine TMP in actual samples, with average recoveries of 96.8%-102.0%.
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Objective: To prepare the molecularly imprinted polymer (MIPs) of L-tetrahydropalmatine (L-THP) by the molecular imprinting technique and study on solid-phase extraction. Methods: Using L-THP as template, methyl acrylic acid (MAA) as functional monmer, and ehtylene glycol dimethacrylate (EDMA) as a cross-linking agent to prepare the L-THP-MIPs. A test was conducted to investigate the selectivity and the specificity of solid-phase extraction. Results: The experiment showed that the MIPs had the specific adsorption to L-THP, but did not have the specific adsorption to corydaline the structural analogue with L-THP. Conclusion: The L-THP-MIPs have a good selectivity and the specificity of L-THP.
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Lysozyme, pepsin, ovalbumin, hemoglobin andγ-globumin were chosen as templates to investigate the imprinting capability of amphoteric polyacrylamide cryogels. Prepolymerizing solutions contained acrylic acid and allyl amine, as well as acrylamide and N,N'-methylenebisacrylamide as the functional monomers. As a result there were both acidic and basic functional groups in the polymers, facilitating effective interactions with likewise amphoteric proteins. The proteins differ greatly and cover wide scopes of molecular weights and isoelectric points. Regardless of the values of the molecular weights and isoelectric points, all the templates gave higher retentions on the MIP tubes than on the NIP tube. The MIP of lysozyme indicated the highest imprinting factor of 7. 0, and that of γ-globumin showed the lowest, 2. 0. The values of other proteins were intervenient. Conclusively the amphoteric polyacrylamide cryogels were suitable imprinting materials for various proteins, and could potentially be used for protein recognition, purification, and depletion.
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The molecularly imprinted separating medium with halloysite nanotubes as carrier, which were environmentally friendly natural silica substrate nano-materials, aspirin as template molecule and acrylamide as functional monomer was synthesized using reversible addition fragmentation chain transfer polymerization. The template molecule and monomer were bound to stable composite at 1: 2 using the method of ultraviolet spectroscopy combined with Lamber-Beer theory at molecular level. The morphology and adsorption capacity of imprinted material was studied with Fourier transform infrared spectrometer ( FT-IR ) , transmission electron microscope ( TEM) , static adsorption and selective adsorption. The experimental results showed that a good uniformity of imprinted layer with the thickness of 38 nm was coated steadily on the halloysite nanotubes surface. Compared with the conventional surface imprinted material and the material with silica gel as carrier, our molecularly imprinted material had the characteristics of high adsorption capacity and favorable imprinted effect. Its imprinted factor achieved to 3. 5. The molecularly imprinted material was applied for mimetic intestinal juice diffusion experiment. The experimental results indicated that the imprinted material release the aspirin for 12 h, which was 2 times for non imprinted material for only 6 h, demonstrating excellent drug release result, which provided basic data for potential applications of drug carrier.
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Molecularly imprinted polymers for dimethoate recognition were synthesized by the precipitation polymerization technique using methyl methacrylate (MMA) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. The morphology, adsorption and recognition properties were investigated by scanning electron microscopy (SEM), static adsorption test, and competitive adsorption test. To obtain the best selectivity and binding performance, the synthesis and adsorption conditions of MIPs were optimized through single factor experiments. Under the optimized conditions, the resultant polymers exhibited uniform size, satisfactory binding capacity and significant selectivity. Furthermore, the imprinted polymers were successfully applied as a specific solid-phase extractants combined with high performance liquid chromatography (HPLC) for determination of dimethoate residues in the cucumber samples. The average recoveries of three spiked samples ranged from 78.5% to 87.9% with the relative standard deviations (RSDs) less than 4.4% and the limit of detection (LOD) obtained for dimethoate as low as 2.3μg/mL.
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A Co2+ ion-mediated formaldehyde imprinted polymer ( MIP) was prepared by coordination polymerization method in present work and its surface structure characterized by using IR spectrum and scanning electron microscope ( SEM). Inversed phase gas chromatography ( IGC) technique using this formaldehyde imprinted polymer as stationary phase was utilized to investigate on the retention selectivity, isotherm adsorption and adsorption thermodynamics for this imprint material toward the template and its structural analogue. Also, the ability of this polymer in the removal of formaldehyde from room atmosphere was explored. Results indicated that the capacity of the template on the molecularly imprinted polymers (MIPs) column was much higher than that of aldehyde and the lower column temperature and flow rate of carrier gas was beneficial for the selective retention of imprint material toward the template molecule, possessing a higher capacity factor of 61. 1 for the template and a higher separation factor of 10. 66 for this imprint polymer toward formaldehyde and aldehyde under the optimized chromatographic conditions ( column temperature: 363 K;flow rate of carrier gase: 7. 0 mL/ min; injection volume: 3. 0 μL). An approximate linear adsorption isotherm for the template and a BET Ⅲ one for the analogue on the MIPs was observed. In addition, this molecularly imprinted polymer was shown with higher capability in the removal of formaldehyde from room atmosphere.
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Trimethoprim molecularly imprinted polymer (MIP) was prepared as the coating of stir bar sorptive extraction (SBSE) and applied to the trace analysis of trimethoprim and three sulfonamides in complex samples.The MIP-coating was about 21.5 μm thickness with the relative standard deviations (RSD) of 5.9％ (n=10).It was homogeneous and dense with good thermal and chemical stability.The extraction capability of the MIP-coating was 1.7 times over that of the non imprinted polymer (NIP) coating.The MIP coating exhibited selective adsorption ability to sulfonamides,triazines and methotrexate besides antibacterial synergists.The methods for the determination of trimethoprim and three sulfonamides by MIP-coated stir bar sorptive extraction coupled with HPLC were developed.It was successfully applied to the trace trimethoprim analysis in spiked urine and plasma samples.The linear range was 5 to 200 μg/L and the detection limit was 1.6 μg/L.The recoveries in urine and plasma samples were 84.5％ to 91.7％ with RSDs of 2.9％ -4.4％,71.9％ to 85.1％ with RSDs of 3.0％ -7.3％,respectively.The trimethoprim MIP-coated stir bar was also applied to the trace sulfonamides analysis in spiked milk sample.The linear range was 10-200 μg/L,the detection limit was within the range of 4.5-6.1 μg/L,and the recovery was 83.2％ - 110.2％ with RSDs of 4.1％ -8.0％.
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An S-naproxen（S-NAP）molecularly imprinted monolithic stationary phase（MIMSP）with specific recognition for S-NAP and naproxen（NAP）was prepared by in situ technique,utilizing 4-vinylpridine（4-VP）as a function monomer,ethylene glycol dimethacrylate（EDMA）as a cross-linking agent,and low-polar solvents（toluene and dodecanol）as porogenic solvents.The selectivity of the polymers for S-NAP and NAP was evaluated by high performance liquid chromatography（HPLC）.The binding characteristics were tested by Scatchard analysis.Racemic NAP could be specifically separated to some extent.At the same time,NAP could be separated from ibuprofen under optimized conditions.Scatchard analysis showed that two classes of binding sites existed in the S-NAP-imprinted polymers,with their dissociation constants estimated to be 1.045 and 5.496 μM,respectively.The results demonstrate that S-NAP and NAP can be recognized specifically on the obtained MIMSP.
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An S-naproxen (S-NAP) molecularly imprinted monolithic stationary phase (MIMSP) with specific recognition for S-NAP and naproxen (NAP) was prepared by in situ technique,utilizing 4-vinylpridine (4-VP) as a function monomer,ethylene glycol dimethacrylate (EDMA) as a cross-linking agent,and low-polar solvents (toluene and dodecanol) as porogenic solvents.The selectivity of the polymers for S-NAP and NAP was evaluated by high performance liquid chromatography (HPLC).The binding characteristics were tested by Scatchard analysis.Racemic NAP could be specifically separated to some extent.At the same time,NAP could be separated from ibuprofen under optimized conditions.Scatchard analysis showed that two classes of binding sites existed in the S-NAP-imprinted polymers,with their dissociation constants estimated to be 1.045 and 5.496 μM,respectively.The results demonstrate that S-NAP and NAP can be recognized specifically on the obtained MIMSP.
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Two p-phenylenediamine (p-PD)-imprinted polymers, P (MAA) and P (AA), were synthesized using methacrylic acid (MAA) and acrylamide(AA) as functional monomer, respectively, in order to prepare molecular recognition material with high selectivity for p-PD and explore the feasibility of methods such as molecular spectrometry and computational approach of quantum chemistry for the selection of functional mono mer with high imprinting efficiency.The molecular recognition properties of the imprinted polymers were evaluated by high performance liquid chromatography.The results indicated that P(AA) exhibited no imprint ing effect for p-PD, while P(MAA) can bind p-PD selectively(k' =3.57), which showed remarkable imprint ing effect (IF=2.95), and p-PD and its analogues o-phenylenediamine and p-aminobenzoic acid can almost realize baseline separation on P (MAA) column in the mobile phase of methanol.Furthermore, we made a comparative study on the interaction of p-PD with MAA and AA by spectroscopic techniques such as UV and fluorometry as well as HF/6-31G~* computational approach.The results demonstrated that the complex of p-PD-MAA was more stable than that of p-PD-AA, which can give a good explanation for the molecular recog nition properties of P (MAA) and P (AA).The study indicated that both molecular spectrometry (UV and fluorometry)and computational approach of quantum chemistry can be employed as efficient means for the selection of efficient functional monomer.The results showed that fluorometry is sensitive and convenient for the choice of functional monomer if the template molecule is fluorescent.
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A molecularly imprinted polymer (MIP) using benzoic acid as template molecule, 4-vinyl pyridine (4-VP) as functional monomer, ethylene dimethacrylate (EDMA) as cross-linker, was prepared by bulk polymerization. The needle-type gas concentrator was developed using the MIP as adsorption medium. The device was coupled with gas chromatography (GC) for the analysis of volatile organic compounds (VOCs). The effect of polymerization conditions on adsorption property, such as polymerization time, ratio of the reagents, pre-polymerization time, type of solvents, type of template molecules, has been evaluated. The results of gas chromatographic analysis demonstrated that the optimum conditions for getting the best adsorption performance of the synthesized were polymerization time 6 h at 60 ℃, the ratio of the reagents (template molecule : functional monomer : cross-linker) 1∶ 4∶ 20, pre-polymerization time of 3 h, acetonitrile as solvent, benzoic acid as template.
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A novel molecularly imprinted polymer with adequate attractability for Schistosoma japonicum miracidia was prepared.When adulterated with polyvinyl alcohol(PVA),the fabricated film with good swelling property was formed which can suspend on water and slowly release XF(a chemical to be published).This reusable film can well attract Sch-istosoma japonicum miracidia,and hopefully be used in the prevention of schistosome infection.
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AIM: To investigate the adsorption mechanism of pueraria on the molecular imprinting polywer(MIP) and Scatchard analysis was carried out. METHODS: Pueraria MIP was synthesized using pueraria as the template,acrylamide as the functional monomer and ethylene glycol dimethaerylate(EDMA) as the crosslinker. RESULTS: The result showed that at least two classes of binding sites were formed in the imprinted polymer.Extracting compounds from Radix Pueraria was separated by MIP. CONCLUSION: The component of the products is analyzed by HPLC.The result shows that the final products contain pueraria and the other two kinds of isoflavone.