Non-imprinted Microspheres Research Articles

Synthesis and characterization of azoxystrobin hydrophilic molecularly imprinted microspheres

In this research, hydrophilic molecularly imprinted microspheres (HMIPs) for azoxystrobin were successfully synthesized through precipitation polymerization. The adsorption capacities of HMIPs for azoxystrobin in water medium were higher than ordinary molecularly imprinted microspheres (MIPs), and HMIPs exhibited good hydrophilic properties. HMIPs and non-imprinted microspheres (HNIPs) were characterized by FT-IR, SEM, laser particle size analyzer and TGA. Comparing with HNIPs, azoxystrobin had a significant influence on morphologys and sizes of HMIPs. The Langmuir adsorption isotherm illustrated each binding site of HMIPs had the same adsorption capacity. The Lagergran pseudo-second-order kinetic model indicated the adsorption process between azoxystrobin and HMIPs was chemical adsorption. BET test illustrated HMIPs had bigger specific surface areas than HNIPs. Selective adsorption indicated that HMIPs had highly specific recognition of azoxystrobin. HMIPs successfully exhibited high selectivity and high hydrophilicity in water medium.

Preparation and characterization of hydrophilic molecularly imprinted microspheres for difenoconazole

Hydrophilic molecularly imprinted microspheres (HMIMs) for difenoconazole were prepared by precipitation polymerization using 2-hydroxypropyl methacrylate (HPMA) as functional monomer, ethylene glycol dimethacrylate as cross-linker, azobisisobutyronitrile as initiator, and mixture of butanone and n-heptane (6:4, V:V) as solvent. The morphological particle sizes and structures were determined via scanning electron microscopy, laser particle size analyzer, and Fourier transform infrared spectrometry. The average particle size of HMIMs and hydrophilic molecularly non-imprinted microspheres (HNIMs) were 2.72 and 3.28 μm, respectively. Binding experiments were performed in distilled water to evaluate the adsorption capacity of the obtained microspheres towards difenoconazole. Scatchard model shows the maximum adsorption of HMIMs and HNIMs for difenoconazole are 65.04 and 56.97 mg g−1. Langmuir isotherm presents Q max of HMIMs and HNIMs are 62.89 and 53.19 mg g−1. Pseudo-second-order kinetic model displayed a good linear relation and illustrated that the adsorption process of HMIMs is belong to chemical adsorption. Selectivity analysis presented HMIM1 possessed highly specific binding sites for difenoconazole.

Preparation and Chromatographic Application of β-Cyclodextrin Molecularly Imprinted Microspheres for Paeoniflorin.

The application of molecular imprinting technology in the separation and purification of active ingredients in natural products was widely reported, but remains a challenge. Enrichment and separation are especially limited. A surface imprinting technique was reported to synthesize molecularly imprinted microspheres (MIMs) in this article. With paeoniflorin (PF) as the template molecule, β-cyclodextrin (β-CD) and acrylamide (AA) as the functional monomers, and poly(glycidyl methacrylate, GMA) microspheres (PGMA) as the backing material. MIMs have been characterized by FTIR and FESEM. Adsorption experiments indicated the adsorption capacity of MIMs was superior to those comparative non-imprinted microspheres (NIMs) and the binding isotherm of MIMs was in good agreement with the two-site binding model. The baseline separation of PF and its structural analogue albiflorin (AF) were achieved on the new MIMs packed column. MIMs showed good affinity and efficiency for separation of PF and AF compared with those comparative NIMs. The approach of fabricating MIMs is simple, rapid, and inexpensive, and may shed new light on the application of MIMs as a liquid chromatography stationary phase to separate and analyze PF and AF from the Red peony root extracts.

Synthesis and characterization of uranyl ion-imprinted microspheres based on amidoximated modified alginate

Surface ion-imprinting technique was utilized for the preparation of surface ion-imprinted chelating microspheres based on amidoximated modified alginate (U-AOX) in presence of uranyl ions as a template and glutaraldehyde cross-linker. Different instrumental techniques such as elemental analysis, scanning electron microscope (SEM), FTIR, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction spectra were employed for full investigation of the manufactured materials. The synthesized microspheres displayed a higher ability for selective extraction of UO22+ when compared to the non-imprinted microspheres (NI-AOX). In addition, the essential parameters such as pH, temperature, time and initial uranyl ion concentration were evaluated in order to optimize the conditions of the adsorption process. The results indicated that pH 5 was the best for the UO22+ removal, also, the adsorption was endothermic in nature, follows the second-order kinetics and the adsorption isotherm showed the best fit with Langmuir model with maximum adsorption capacity of 155±1 and 64±1mg/g for both U-AOX and NI-AOX respectively. Desorption and regeneration had been carried out using 0.5M HNO3 solution and the results indicated that the microspheres maintained about 96% of its original efficiency after five consecutive adsorption–desorption cycles.

Fragment-imprinted microspheres for the extraction of sulfonamides

Fragment-imprinted microspheres (FIMs) were synthesized by suspension polymerization of 4-sulfa-6-chloropyrimidine (the template), methacrylic acid and styrene (the mixed functional monomers), divinylbenzene (the crosslinker), and azobisisobutyronitrile (the initiator). The optimum conditions were obtained by an orthogonal experiment. After removal of the templates, the microspheres serve as a material to fairly specifically bind sulfonamides, the absorption capacity being 6.32 mg g–1, whereas the absorption by non-imprinted microspheres is 1.68 mg g−1. A method was worked out for the simultaneous determination of five sulfonamides by solid phase extraction (using the FIMs) coupled to HPLC, and applied to analyze milk samples. The recoveries are within 87.6 and 96.5 %, with relative standard deviations between 1.25 and 2.89 %.

Detection of degradation products of chemical warfare agents by highly porous molecularly imprinted microspheres

The multiplication of terrorist actions in the recent events is alarming and the detection of chemical warfare agents (CWAs) has become one of the highest research priorities in the fields of security and public health. The biomimetic properties of molecularly imprinted polymers (MIPs) render them attractive for molecular recognition as well as sensing purposes. The degradation products of easily hydrolysable organophosphorus nerve agents such as pinacolyl methylphosphonate (PMP), a hydrolysis by-product of soman, are often used as templates in MIP synthesis. In this study, we describe the first example of PMP-imprinted polymer microspheres synthesized by precipitation polymerization. This one-step process involves methacrylic acid (MAA) as the monomer and divinylbenzene (DVB) as the cross-linker, in a toluene/acetonitrile mixture. Subsequent morphological characterizations of the PMP-imprinted particles show that they have diameters between 1 and 10 mum (as opposed to 4-5 mum for the non-imprinted microspheres), surface areas of up to 680 m(2) g(-1) and high porosities with pore sizes smaller than 2 nm. The present investigation also evidences the imprinting effect via batch binding experiments and reports on the use of a novel fluorescence-based methodology, where 4-methylumbelliferone (4MU) is utilised as a sensing agent to determine the PMP concentration in solution.

Preparation of molecularly imprinted cyclodextrin microspheres

Molecularly imprinted cyclodextrins (MI-CDs) are prepared by cross-linking CDs in the presence of a template molecule. The binding ability of MI-CDs to the template molecule is specific; therefore, MI-CDs will prove to be useful materials. In this study, we prepared microspheres of MI-CDs (MSs-MI-CD) in a dimethylsulfoxide/poly(dimethylsiloxane) (PDMS) emulsion, using cholesterol as the template molecule. MSs-MI-CD were prepared under various conditions and were evaluated with respect to their morphology, size, and binding ability. MSs-MI-CD prepared at 65 °C were in an aggregated form; however, we could prepare separated and uniform MSs-MI-CD at 95 °C. The viscosity of PDMS influenced the size of MSs-MI-CD. The mean particle diameters of MSs-MI-CD prepared with 50 and 1000 mm 2/s PDMS were 146 and 43 μm, respectively. The binding ability of MSs-MI-CD to cholesterol was higher than that of non-imprinted microspheres. Cholesterol imprinting also promoted the binding ability to other steroids; however, the increase in binding ability was most remarkable in the case of cholesterol, suggesting that we successfully introduced the cholesterol-specific binding ability into MSs-MI-CD. The novel MSs-MI-CD preparation method is useful and simple, and it will provide opportunities for further studies on the specific binding ability of MI-CDs.

Preparation of ferrocyanide-imprinted pyridine-carrying microspheres by surface imprinting polymerization.

Ferrocyanide-imprinted pyridine-carrying microspheres were prepared using ferrocyanide ions as a template. This method is based on a surface imprinting technique from the seed emulsion that consisted of 4-vinylpyridine (functional monomer), styrene, and butyl acrylate and a water mixture polymerization by a radical initiator. The ferrocyanide-imprinted microspheres had about 200 times higher adsorption affinity over the non-imprinted microspheres in ferrocyanide (template) ion adsorption. This imprinted microspheres also adsorbed other tripolyphosphate, pyrophosphate, and phosphate anions much more strongly than the non-imprinted microspheres did, but were not particularly specific in ferrocyanide ion adsorption.