Rapid and efficient enantioseparation of (S)‐amlodipine by surface‐imprinted core–shell polymer microspheres

We present a protocol for the preparation of surface‐imprinted polymer microspheres by core–shell precipitation polymerization for the enantioseparation of (S)‐amlodipine. In this work, submicron mesoporous silica microspheres were prepared with gemini cationic surfactant as soft template. Molecularly imprinted polymers were coated on the silica supports with a low level of crosslinking, and the thickness of the thin‐walled imprinted shell was about 45 nm. The material showed fast binding kinetics for (S)‐amlodipine (within only 20 min for complete equilibrium), and the saturation adsorption capacity reached 309.2 mg/g, indicating the good accessibility of binding sites and improved mass transfer for target molecule. The imprinted microspheres exhibited an appreciable enantiomeric excess of (S)‐amlodipine of 11.3% when used as a glass chromatography column for the enantioseparation of (S)‐amlodipine from amlodipine besylate without extra chiral additives. The surface‐imprinted materials display potentially amplification for industrial enantioseparation of (S)‐amlodipine.     

Molecularly imprinted polymeric shell coated monodisperse‐porous silica microspheres as a stationary phase for microfluidic boronate affinity chromatography

Molecular imprinting of cis‐diol functionalized agents via boronate affinity interaction has been usually performed using nanoparticles as a support which cannot be utilized as a stationary phase in continuous microcolumn applications. In this study, monodisperse‐porous, spherical silica particles in the micron‐size range, with bimodal pore diameter distribution were selected as a new support for the synthesis of a molecularly imprinted boronate affinity sorbent, using a cis‐diol functionalized agent as the template. A specific surface area of 158 m²/g was achieved with the imprinted sorbent by using monodisperse‐porous silica microspheres containing both mesoporous and macroporous compartments as the support. High porosity originating from the macroporous compartment and sufficiently high particle size provided good column permeability to the imprinted sorbent in microcolumn applications. The mesoporous compartment provided a large surface area for the parking of imprinted molecules while the macroporous compartment facilitated the intraparticular diffusion of imprinted target within the microsphere interior. A microfluidic boronate affinity system was first constructed by using molecularly imprinted polymeric shell coated monodisperse‐porous silica microspheres as a stationary phase. The synthetic route for the imprinting process, the reversible adsorption/ desorption behavior of selected target and the selectivity of imprinted sorbent in both batch and microfluidic boronate affinity chromatography systems are reported.     

Thermo‐sensitive surface molecularly imprinted magnetic microspheres based on bio‐macromolecules and their specific recognition of bovine serum albumin

Bovine serum albumin imprinted magnetic microspheres, with functional monomers of modified chitosan, N‐isopropylacrylamide and sulfobetaine methacrylate, were successfully prepared and characterized in detail. Computational analyses showed that during the preparation process, modified chitosan can effortlessly form multiple non‐covalent bonds with protein molecules. Temperature‐sensitive N‐isopropylacrylamide improves the elution efficiency by abating the mass transfer resistance. Meanwhile, the zwitterionic sulfobetaine methacrylate strongly interacts with H₂O molecules, remarkably reducing the non‐specific adsorption. The specific bovine serum albumin adsorption performances of the prepared imprinted material were then determined. The adsorption amount reached 86.87 mg/g and the imprinting factor was 6.49. These excellent specific adsorption properties are attributed to the synergetic effects of the different monomers. The fabricated imprinted material not only exhibits great prospects as a biosensor or separation material for protein molecules, but also provides a collaborative strategy for preparing multi‐functional imprinted materials.     

One‐pot synthesis of surface‐functionalized molecularly imprinted polymer microspheres by iniferter‐induced “living” radical precipitation polymerization

This article describes for the first time the development of a new polymerization technique by introducing iniferter‐induced “living” radical polymerization mechanism into precipitation polymerization and its application in the molecular imprinting field. The resulting iniferter‐induced “living” radical precipitation polymerization (ILRPP) has proven to be an effective approach for generating not only narrow disperse poly(ethylene glycol dimethacrylate) microspheres but also molecularly imprinted polymer (MIP) microspheres with obvious molecular imprinting effects towards the template (a herbicide 2,4‐dichlorophenoxyacetic acid (2,4‐D)), rather fast template rebinding kinetics, and appreciable selectivity over structurally related compounds. The binding association constant K_a and apparent maximum number N_max for the high‐affinity sites of the 2,4‐D imprinted polymer were determined by Scatchard analysis and found to be 1.18 × 10⁴ M^?1 and 4.37 μmol/g, respectively. In addition, the general applicability of ILRPP in molecular imprinting was also confirmed by the successful preparation of MIP microspheres with another template (2‐chloromandelic acid). In particular, the living nature of ILRPP makes it highly useful for the facile one‐pot synthesis of functional polymer/MIP microspheres with surface‐bound iniferter groups, which allows their direct controlled surface modification via surface‐initiated iniferter polymerization and is thus of great potential in preparing advanced polymer/MIP materials. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3217–3228, 2010     

Constituting of a new surface‐initiating system on polymeric microspheres and preparation of basic protein surface‐imprinted material in aqueous solution

In this work, a new surface‐initiating system was constituted on the surfaces of cross‐linked polyvinyl alcohol (CPVA) microspheres, and on this basis, papain surface‐imprinted material was successfully prepared in aqueous solution. CPVA microspheres were modified with chlorethamin as reagent, and so a mass of primary amino group was introduced onto CPVA microspheres. Whereupon, a surface initiating system (−NH₂/S₂O₈²⁻) was formed at the interface between the microspheres and aqueous solution, in which papain as template protein, 4‐styrene sulfonate (SSS) as functional monomer, N,N′‐methylenebisacrylamide (MBA) as cross‐linker and (NH₄)₂S₂O₈ as initiator were all dissolved. In neutral solution, the polypeptide chains of papain as a basic protein were positively charged, and the molecules of anionic monomer SSS would spontaneously gather around papain polypeptide chain, forming complex by right of strong electrostatic interaction. The free radicals produced on CPVA microspheres initiated the monomer SSS around papain polypeptide chain and the cross‐linker MBA to produce graft/cross‐linking polymerization, and at the same time, papain macromolecules were embed in the cross‐linked networks. As a result, the graft/cross‐linking polymerizing of SSS and the molecule imprinting of papain were synchronously carried out, and papain surface‐imprinted material, MIP‐PSSS/CPVA microspheres, was obtained. The experimental results show that the papain surface‐imprinted material has excellent binding affinity and high recognition selectivity for papain. The binding capacity of MIP‐PSSS/CPVA microspheres for papain reaches 44 mg/g, and relative to another basic protein, trypsin (TRY) as contrast protein, the selectivity coefficient of MIP‐PSSS/CPVA microspheres for papain is 14.35, displaying very high recognition specificity.     

Preparation of “dummy” l‐phenylalanine molecularly imprinted microspheres by using ionic liquid as a template and functional monomer

In this study, dummy imprinting technology was employed for the preparation of l‐ phenylalanine‐imprinted microspheres. Ionic liquids were utilized as both a “dummy” template and functional monomer, and 4‐vinylpyridine and ethylene glycol dimethacrylate were used as the assistant monomer and cross‐linker, respectively, for preparing a surface‐imprinted polymer on poly(divinylbenzene) microspheres. By the results obtained by theoretical investigation, the interaction between the template and monomer complex was improved as compared with that between the template and the traditional l‐ phenylalanine‐imprinted polymer. The batch experiments indicated that the imprinting factor reached 2.5. Scatchard analysis demonstrated that the obtained “dummy” molecularly imprinted microspheres exhibited an affinity of 77.4 M·10^?4, significantly higher that of a traditional polymer directly prepared by l‐ phenylalanine, which is in agreement with theoretical results. Competitive adsorption experiments also showed that the molecularly imprinted polymer with the dummy template effectively isolated l‐ phenylalanine from l‐ histidine and l‐ tryptophan with separation factors of 5.68 and 2.68, respectively. All these results demonstrated that the polymerizable ionic liquid as the dummy template could enhance the affinity and selectivity of molecularly imprinted polymer, thereby promoting the development of imprinting technology for biomolecules.     

Photoirradiation surface molecularly imprinted polymers for the separation of 6‐O‐α‐d‐maltosyl‐β‐cyclodextrin

Photoirradiation surface molecularly imprinted polymers for the separation of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin were synthesized using functionalized silica as a matrix, 4‐(phenyldiazenyl)phenol as a light‐sensitive monomer, and 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin as a template. Fourier transform infrared spectroscopy results indicated that 4‐(phenyldiazenyl)phenol was grafted onto the surface of functionalized silica. The obtained imprinted polymers exhibited specific recognition toward 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin. Equilibrium binding experiments showed that the photoirradiation surface molecularly imprinted polymers obtained the maximum adsorption amount of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin at 20.5 mg/g. In binding kinetic experiments, the adsorption reached saturation within 2 h with binding capacity of 72.8%. The experimental results showed that the adsorption capacity and selectivity of imprinted polymers were effective for the separation of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin, indicating that imprinted polymers could be used to isolate 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin from a conversion mixture containing β‐cyclodextrin and maltose. The results showed that the imprinted polymers prepared by this method were very promising for the selective separation of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin.     

Preparation and application of hollow molecularly imprinted polymers with a super‐high selectivity to the template protein

Protein‐imprinted polymers with hollow cores that have a super‐high imprinting factor were prepared by etching the core of the surface‐imprinted polymers that used silica particles as the support. Lysozyme as template was modified onto the surface of silica particles by a covalent method, and after polymerization and the removal of template molecules, channels through the polymer layer were formed, which allowed a single‐protein molecule to come into the hollow core and attach to the binding sites inside the polymer layer. The adsorption experiments demonstrated that the hollow imprinted polymers had an extremely high binding capacity and selectivity, and thus a super‐high imprinting factor was obtained. The as‐prepared imprinted polymers were used to separate the template lysozyme from egg white successfully, indicating its high selectivity and potential application in the field of separation of protein from real samples.     

Solid‐phase extraction based on a molecularly imprinted polymer nanoshell at the surface of silica nanospheres for the specific enrichment and identification of alkaloids from Crinum asiaticum L. var. sinicum

A molecularly imprinted nanoshell on the surface of silica nanospheres was prepared for specific enrichment and identification of alkaloids from Crinum asiaticum L. var. sinicum . The nanoshell was synthesized by surface polymerization using lycorine as the template, acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross‐linker, 2′,2‐azobisisobutyronitrile as the initiator and acetonitrile as the pore‐forming agent. The core–shell nanospheres were characterized by transmission electron microscopy and infrared spectroscopy, and the results show that the nanoshell layer was homogeneously attached to the surface of vinyl‐modified SiO₂ nanospheres. The adsorption capacity of the nanospheres was estimated by binding equilibrium and adsorption kinetics experiments. The maximum adsorption amount of lycorine on the nanospheres was 6.68 μmol/g and the imprinting factor was nearly 2.5, indicating a good imprinting effect. The nanospheres were successfully applied in solid‐phase extraction for lycorine from Crinum asaticum L. var. sinicum and detection of target molecule in rat metabolites. The average recoveries of lycorine in Crinum asaticum L. var. sinicum extraction and rat metabolites were 93.5 ± 0.6% (n = 3) and 91.6 ± 1.9% (n = 3), respectively. This work provides a simple approach for the fabrication of a molecularly imprinted nanoshell at the surface of silica nanospheres‐based solid‐phase extraction for drug analysis.     

Synthesis of a molecularly imprinted polymer on mSiO2@Fe3O4 for the selective adsorption of atrazine

Atrazine contamination of water is of considerable concern because of the potential hazard to human health. In this study, a magnetic molecularly imprinted polymer for atrazine was prepared by the surface‐imprinting technique using Fe₃O₄ as the core, mesoporous silica as the carrier, atrazine as the template, and itaconic acid as the functional monomer. The magnetic molecularly imprinted polymer was characterized by Fourier‐transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, and vibration‐sample magnetometry. The binding properties of the magnetic molecularly imprinted polymer toward atrazine were investigated by adsorption isotherms, kinetics, and competitive adsorption. It was found that the adsorption equilibrium was achieved within 2 h, the maximum adsorption capacity of atrazine was 8.8 μmol/g, and the adsorption process could be well described by the Langmuir isotherm model and pseudo‐second‐order kinetic model. The magnetic molecularly imprinted polymer exhibited good adsorption selectivity for atrazine with respect to structural analogues, such as cyanazine, simetryne, and prometryn. The reusability of the magnetic molecularly imprinted polymer was demonstrated for at least five repeated cycles without a significant decrease in adsorption capacity. These results suggested that the magnetic molecularly imprinted polymer could be used as an efficient material for the selective adsorption and removal of atrazine from water samples.     

A Facile and Universal Method to Prepare Hydrophilic Molecularly Imprinted Microspheres by Encapsulating a Polymer in Hollow Mesoporous Silica Microspheres

Hydrophilic molecularly imprinted microspheres (MIP@SiO₂) for the adsorption of water‐soluble molecules in real aqueous samples were successfully synthesized. In this strategy, a molecular imprinted polymer (MIP) was encapsulated in the hollow core of hollow mesoporous silica (HMS) particles via a ‘ship‐in‐a‐bottle’ process. As the HMS shell contains plenty of Si‐OH groups, the as‐prepared microspheres proved to be hydrophilic and could be well dispersed in water. On the other hand, the MIP encapsulated in the HMS could specifically recognize small molecules with good binding efficiency through the mesoporous silica shell. Binding experiments in real aqueous solutions showed that the MIP@SiO₂ composites have excellent recognition ability for specific molecules. Thus, MIP@SiO₂ are highly promising alternatives to biological receptors with great potential for many analytical applications, such as environmental, food, and clinical analyses and other areas.     

Silica particles coated with azobenzene-containing photoresponsive molecule-imprinted skin layer

We developed a novel type of azobenzene-containing photoresponsive molecule-imprinted silica microspheres. Ibuprofen and activated silica particles were used as template molecules and substrates, respectively. Pre-synthesized azobenzene-based monomers were chemically bonded on the surface of silica particles. Template–monomer complexes were formed relying on hydrogen bonding. Then skin layer was formed by graft polymerization of azobenzene-based monomers. After that, ibuprofen molecules were removed from their embedded spaces. The vacant spaces on the surface of particles were easily accessible for the template molecules. Furthermore, photoinduced trans–cis isomerization of azobenzene chromophores within imprinted vacant spaces was able to regulate their substrate affinity. The results demonstrated that the imprinted silica microspheres possessed obvious molecular imprinting effects towards the template ibuprofen, rather fast template rebinding kinetics, and appreciate selectivity over structurally related compounds.     

Imprinted silica nanoparticles coated with N‐propylsilylmorpholine‐4‐carboxamide for the determination of m‐cresol in synthetic and real samples

m‐Cresol‐imprinted silica nanoparticles coated with N‐propylsilylmorpholine‐4‐carboxamide have been developed that contain specific pockets for the selective uptake of m‐cresol. Silica nanoparticles were synthesized by a sol–gel process followed by functionalization of their surface with N‐propylsilylmorpholine‐4‐carboxamide. The formation of m‐cresol‐imprinted silica nanoparticles was confirmed by UV‐Vis spectrophotometry, infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. Electron microscopic studies revealed the formation of monodispersed imprinted silica nanoparticles with spherical shape and an average size of 83 nm. The developed nanoparticles were filled in a syringe and used for the extraction of m‐cresol from aqueous samples followed by quantification using high‐performance liquid chromatography with diode array detection. Various adsorption experiments showed that developed m‐cresol‐imprinted silica nanoparticles exhibited a high adsorption capacity and selectivity and offered a fast kinetics for rebinding m‐cresol. The chromatographic quantification was achieved using mobile phase consisting of acetonitrile/water (70:30 v/v) at an isocratic flow rate of 1.0 mL/min using a reversed‐phase C₁₈ column and detection at λ_max = 275 nm. The limits of detection and quantification were 1.86 and 22.32 ng/mL, respectively, for the developed method. The percent recoveries ranged from 96.66–103.33% in the spiked samples. This combination of this nanotechnique with molecular imprinting was proved as a reliable, sensitive and selective method for determining the target from synthetic and real samples.     

Preparation of chitosan‐based molecularly imprinted material for enantioseparation of racemic mandelic acid in aqueous medium by solid phase extraction

An S‐mandelic acid imprinted chitosan resin was synthesized by cross‐linking chitosan with glutaraldehyde in 2% acetic acid solution. S‐Mandelic acid imprinted chitosan resin was used to enantioselectively separate racemic mandelic acid in aqueous medium. When keeping the pH of sample solution (100 mM Tris‐H₃PO₄) at 3.5 and adsorption time at 40 min, the enantiomer excess of mandelic acid in supernatant was 78.8%. The adsorption capacities of S‐mandelic acid imprinted chitosan resin for S‐ and R‐mandelic acid were determined to be 29.5 and 2.03 mg/g, respectively. While the adsorption capacities of non‐imprinted cross‐linked chitosan for S‐ and R‐mandelic acid were 2.10 and 2.08 mg/g, respectively. The result suggests that the imprinted caves in S‐mandelic acid imprinted chitosan resin are highly matched with S‐mandelic acid molecule in space structure and spatial arrangement of action sites. Interestingly, the enantiomer excess value of mandelic acid in supernatant after adsorption of racemic mandelic acid by R‐mandelic acid imprinted cross‐linked chitosan was 25.4%. The higher enantiomer excess value by S‐mandelic acid imprinted chitosan resin suggests that the chiral carbons in chitosan and the imprinted caves in S‐mandelic acid imprinted chitosan resin combine to play roles for the enantioselectivity of S‐mandelic acid imprinted chitosan resin toward S‐mandelic acid. Furthermore, the excellent enantioselectivity of S‐mandelic acid imprinted chitosan resin toward S‐mandelic acid demonstrates that using chiral chitosan as functional monomer to prepare molecularly imprinted polymers has great potential in enantioseparation of chiral pharmaceuticals.     

Determination of Parathion‐methyl in Vegetables by Fluorescent‐Labeled Molecular Imprinted Polymer

A novel sensor for the determination of parathion‐methyl based on couple grafting of functional molecular imprinted polymers (MIPs) was fabricated which is developed by anchoring the MIP layer on surfaces of silica particles embedded CdSe quantum dots by surface imprinting technology. The synthesized molecular imprinted silica nanospheres (CdSe@SiO₂@MIP) allow a high selectivity and sensitivity of parathion‐methyl via fluorescence intensity decreasing when the MIP material rebinding the parathion‐methyl molecule. Compared with the MIP fabricated in traditional method, the template of parathion‐methyl was easier to remove from the CdSe@SiO₂@MIP imprinted material. Under optimal conditions, the fluorescence intensity of parathion‐methyl at the imprinted sensor was detected by spectrofluorophotometer. The relative fluorescence intensity of CdSe@SiO₂@MIP decreased linearly with the increasing concentration of parathion‐methyl ranging from 0.013 mg·kg⁻¹ to 2.63 mg·kg⁻¹ with a detection limit (3δ) of 0.004 mg·kg⁻¹ (S/N=3), which is lower than the MIP in tradition. The imprinted film sensor was applied to detect parathion‐methyl in vegetable samples without the interference of other organophosphate pesticides and showed a prosperous application in the field of food safety.     

Selective separation and determination of quercetin from red wine by molecularly imprinted nanoparticles coupled with HPLC and ultraviolet detection

In this study, a highly sensitive and selective sample pretreatment procedure using molecularly imprinted silica nanoparticles was developed for the extraction and determination of quercetin in red wine samples coupled with high‐performance liquid chromatography with ultraviolet detection. The imprinted silica nanoparticles were prepared in the presence of N‐acryoyl‐l ‐aspartic acid (functional monomer), quercetin (template), azobisisobutyronitrile (initiator) and methylene bisacrylamide (cross‐linker) and methanol/water (porogen) via surface‐initiated reversible addition‐fragmentation chain transfer polymerization. Surface characterization was performed and several imprinting parameters were investigated, and the results indicated that adsorption of quercetin on the imprinted silica nanoparticles followed a pseudo‐first‐order adsorption isotherm with a maximum adsorption capacity at 26.4 mg/g within 60 min. The imprinted silica nanoparticles also showed satisfactory selectivity towards quercetin as compared with its structural analogues. Moreover, the imprinted nanoparticles preserved their recognition ability even after five adsorption–desorption cycles. Meanwhile, the nanoparticles were successfully applied to selective extraction of quercetin from red wine with a high recovery (99.7–100.4%). The limit of detection was calculated to be 0.058 μg/mL with a correlation coefficient 0.9996 in the range of 0.2–50 μg/mL. As a result, the developed selective extraction method using molecular imprinting technology simplifies the sample pretreatment procedure before determination of quercetin in real samples.     

Rapid determination of antiviral medication ribavirin in different feedstuffs using a novel magnetic molecularly imprinted polymer coupled with high‐performance liquid chromatography

A novel magnetic molecularly imprinted polymer adsorbing material was successfully synthesized to detect ribavirin in animal feedstuff. Molecularly imprinted polymer was prepared through surface polymerization by using ribavirin as template molecule, methyl methacrylate, and γ‐methacryloxypropyl trimethoxy silane functionalized magnetic mesoporous silica as bifunctional monomers, and ethylene diglycidyl ether as crosslinking agent. The prepared magnetic molecularly imprinted polymer was characterized by scanning electron microscopy and infrared spectroscopy. Static and dynamic adsorption experiments and selective adsorption analysis were performed to evaluate the adsorption and selectivity of magnetic molecularly imprinted polymer. Different experiments were conducted to optimize the magnetic solid‐phase extraction conditions. Under optimal experimental conditions, a magnetic molecularly imprinted solid‐phase extraction coupled with high‐performance liquid chromatography method was successfully developed for ribavirin detection. The established method achieved a satisfactory linear range of 0.20–50 mg/L (R² > 0.99) and a low detection limit (0.081 mg/kg). An average recovery of 92–105% with relative standard deviation of <6.5% was obtained upon the application of the developed method to detect ribavirin in real feedstuff samples. Thus, established method can be used for the rapid and simple separation and detection of added ribavirin in feedstuff.     

Metal‐imprinted microsphere prepared by surface template polymerization and its application to chromatography

A metal ion‐imprinted microsphere was prepared by surface molecular template polymerization. Trimethylolpropane trimethacrylate (TRIM), zinc ions, 1,12‐dodecanediol‐O, O′‐diphenyl phosphonic acid (DDDPA) were used as a crosslinking agent, an imprint molecule, and a functional host molecule. The Zn(II)‐imprinted microspheres, which are spherically well‐defined particles, were prepared by using water‐in‐oil‐in‐water (W/O/W) multiple emulsions. The combination of TRIM and DDDPA serves to align the recognition sites resulting in better template sites produced on the polymer surface. We firstly conducted diagnostic zinc‐ and copper‐ion adsorption tests with the Zn(II)‐imprinted and unimprinted microspheres in order to make an assessment on the effectiveness of the molecular imprinting technique. Further, the metal‐imprinted microspheres were applied to the column operation. The separation and recovery of metals were carried out by an adsorption column packed with the Zn(II)‐imprinted microspheres. This performance was compared to that of commercial chelating resins that possess similar phosphoric functional groups. The Zn(II)‐imprinted polymer shows an extremely high selectivity to the imprinted zinc ions compared to that of the commercial chelating resin. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 689–696, 2000     

Preparation of l‐phenylalanine‐imprinted solid‐phase extraction sorbent by Pickering emulsion polymerization and the selective enrichment of l‐phenylalanine from human urine

A novel l‐ phenylalanine molecularly imprinted solid‐phase extraction sorbent was synthesized by the combination of Pickering emulsion polymerization and ion‐pair dummy template imprinting. Compared to other polymerization methods, the molecularly imprinted polymers thus prepared exhibit a high specific surface, large pore diameter, and appropriate particle size. The key parameters for solid‐phase extraction were optimized, and the result indicated that the molecularly imprinted polymer thus prepared exhibits a good recovery of 98.9% for l‐ phenylalanine. Under the optimized conditions of the procedure, an analytical method for l‐ phenylalanine was well established. By comparing the performance of the molecularly imprinted polymer and a commercial reverse‐phase silica gel, the obtained molecularly imprinted polymer as an solid‐phase extraction sorbent is more suitable, exhibiting high precision (relative standard deviation 3.2%, n = 4) and a low limit of detection (60.0 ± 1.9 nmol·L^?1) for the isolation of l‐ phenylalanine. Based on these results, the combination of the Pickering emulsion polymerization and ion‐pair dummy template imprinting is effective for preparing selective solid‐phase extraction sorbents for the separation of amino acids and organic acids from complex biological samples.     

Highly ordered molecularly imprinted mesoporous silica for selective removal of bisphenol A from wastewater

Selective removal of bisphenol A from wastewater is quite challenging primarily because of its low concentration and matrix complexity. To this end, according to the molecular structure of bisphenol A, we designed a functional monomer for the preparation of molecularly imprinted mesoporous silica using click chemistry reaction. The resultant bisphenol A imprinted mesoporous silica was characterized by transmission electron microscopy, small angle X‐ray diffraction, and N₂ adsorption–desorption experiments. The results indicated that the bisphenol A imprinted mesoporous silica possessed a highly ordered periodic hexagonal mesostructure with the Brunauer–Emmett–Teller surface area of 944.28 m²/g. The bisphenol A imprinted mesoporous silica showed fast adsorption kinetics and the saturated adsorption capacity reached up to 88.6 mg/g at pH 6.5, and with relative selectivity factors ranged from 1.06 to 3.20. The adsorption efficiency of the bisphenol A imprinted mesoporous silica was above 97.96% after five extraction/elution cycles. The bisphenol A imprinted mesoporous silica was further applied to the selective removal of bisphenol A from real wastewater samples and showed great promise in practical applications.