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A water‐compatible method for the diastereoselective synthesis of 2‐trifluormethyl‐1,3‐dioxanes is described. The reaction proceeds under mild reaction conditions using simple inorganic bases; it has a very good substrate scope and can be performed with different Michael acceptors. Additionally, the reaction products can be further functionalized, showing an excellent perspective for future applications. A simple and practical method for the diastereoselective synthesis of fluorinated dioxanes using aqueous fluoral and KOH was developed. The products were obtained with high yields and selectivities, besides they proved to be stable enough to resist further functionalization. The reaction is easily performed and well tolerated with a broad range of substrates. [ABSTRACT FROM AUTHOR]

This work demonstrated the synthesis and design of ultra-bright and ultra-small fluorescent nanoparticles, which were prepared by encapsulating 4-(diphenylamino)benzaldehyde (DPB) in silica cross-linked micellar nanoparticles (SCMNPs). The DPB-doped SCMNPs (DPB-SCMNPs) exhibited ultra-bright fluorescence in an aqueous medium that was 22 times brighter than that of free DPB molecules in an organic solvent. For the first time, density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations were used to confirm that the enhanced brightness of the DPB-SCMNPs was due to a hydrogen bond-induced mechanism. In addition, the 3D fluorescence spectra and the Commission Internationale de L'Eclairage (CIE) diagram were employed to determine the optical properties and emission colour of the DPB-SCMNPs. Moreover, the DPB-SCMNPs were water-soluble, monodisperse and ultra-small (∼12 nm) and should be robust and stable in aqueous media and biological systems. [ABSTRACT FROM AUTHOR]

A superparamagnetic molecularly imprinted biopolymer (SMIBP) was utilized as an eco-friendly and worth welting bio-sorbent and subsequently was applied for selective dispersive solid phase extraction (d-SPE) and selective separation of baclofen from urine samples. This effective solid phase was biopolymer network with imprinted cavities grafted on the surface of Fe 3 O 4 cores possessing an influential SiO 2 layer. The present sorbent easily achieved via co-precipitation and sol-gel processes followed by impressive bio-polymerization route under green and mild reaction conditions. The prepared SMIBP was subsequently characterized by different techniques including SEM, VSM, FT-IR, XRD, TEM and TGA verifying high suitability of the proposed solid phase for trapping and accumulation of target compound. Under optimized conditions recommended by experimental design, understudy SMIBP-d-SPE procedure supplied linear response over 1.0–2500.0 µg L −1 with a satisfactory detection limit close to 0.26 µg L −1 , while repeatability assign to intra-day and inter-day precision as coefficients of variation was lower than 3.9% in both case. These appropriate validation imply high ability of proposed microextraction procedure for clean and effective enrichment of target analyte in complex human urine sample cause consequently leading to accurate analyses at ultra-trace levels. [ABSTRACT FROM AUTHOR]

Versatile molecularly imprinted polymers (MIPs) have been widely applied to various sample matrices, however, molecular recognition in aqueous media is still difficult. Stimuli-responsive MIPs have received increasing attentions due to their unique feature that the molecular recognition is regulated by specific external stimuli. Herein, water-compatible temperature and magnetic dual-responsive MIPs (WC-TMMIPs) with hydrophilic brushes were prepared via reversible addition-fragmentation chain transfer precipitation polymerization for reversible and selective recognition and extraction of bisphenol A (BPA). Transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FT-IR) and vibrating sample magnetometry (VSM) as characterization methods were used to examine the successful synthesis of polymers, and the resultant WC-TMMIPs showed excellent thermosensitivity and simple rapid magnetic separation. Controlled adsorption and release of BPA by temperature regulation were investigated systematically, and the maximum adsorption and removal efficiency toward BPA in aqueous solutions were attained at 35 °C and 45 °C, respectively, as well as a good recoverability was exhibited with the precision less than 5% through five adsorption–desorption cycles. Phenolic structural analogs were tested and good recognition specificity for BPA was displayed. Accordingly, the WC-TMMIPs were employed as adsorbents for magnetic solid-phase extraction (MSPE) and packed SPE of BPA from seawater samples. Using the two modes followed by HPLC-UV determination, excellent linearity was attained in the range of 0.1–14.5 μM and 1.3–125 nM, with low detection limits of 0.02 μM and 0.18 nM, respectively. Satisfactory recoveries for spiked seawater samples were achieved ranging from 86.3–103.5% and 96.2–104.3% with RSD within 2.12–4.33%. The intelligent WC-TMMIPs combining water-compatibility, molecular recognition, magnetic separation, and temperature regulation proved potentially applicable for selective identification, controlled adsorption/release and high-efficiency enrichment/removal of trace targets in complicated aqueous media. [ABSTRACT FROM AUTHOR]

A novel molecularly imprinted solid phase extraction (MISPE) methodology followed by liquid chromatography tandem mass spectrometry (LC–MS/MS) has been developed using cylindrical shaped molecularly imprinted pills for detection of Δ 9 -tetrahydrocannabinol (THC), 11-nor-Δ 9 -tetrahydrocannabinol carboxylic acid (THC-COOH), cannabinol (CBN) and cannabidiol (CBD) in urine and oral fluid (OF). The composition of the molecular imprinted polymer (MIP) was optimized based on the screening results of a non-imprinted polymer library (NIP-library). Thus, acrylamide as functional monomer and ethylene glycol dimethacrylate as cross-linker were selected for the preparation of the MIP, using catechin as a mimic template. MISPE pills were incubated with 0.5 mL urine or OF sample for adsorption of analytes. For desorption, the pills were transferred to a vial with 2 mL of methanol:acetic acid (4:1) and sonicated for 15 min. The elution solvent was evaporated and reconstituted in methanol:formic acid (0.1%) 50:50 to inject in LC–MS/MS. The developed method was linear over the range from 1 to 500 ng mL −1 in urine and from 0.75 to 500 ng mL −1 in OF for all four analytes. Intra- and inter-day imprecision were <15%. Extraction recovery was 50–111%, process efficiency 15.4–54.5% and matrix effect ranged from −78.0 to −6.1%. Finally, the optimized and validated method was applied to 4 urine and 5 OF specimens. This is the first method for the determination of THC, THC-COOH, CBN and CBD in urine and OF using MISPE technology. [ABSTRACT FROM AUTHOR]

ABSTRACT A facile, general, and highly efficient one-pot approach to obtain azobenzene (azo)-containing molecularly imprinted polymer (MIP) nanoparticles with photoresponsive template binding and release properties in aqueous media is described, which involves the combined use of hydrophilic macromolecular chain transfer agent-mediated reversible addition-fragmentation chain transfer precipitation polymerization and easily available water-insoluble azo functional monomers. The resulting azo-containing MIPs were characterized with dynamic laser scattering (DLS), SEM, FTIR, static contact angle and water dispersion studies, and equilibrium binding experiments. They have proven to be nanoparticles (their diameters being around 104-397 nm, as determined by DLS in methanol) with surface-grafted hydrophilic polymer brushes and exhibit excellent pure water-compatible template binding properties. Moreover, obvious photoregulated template binding behaviors were observed for such azo-containing MIP nanoparticles, which led to their largely accelerated template release in the aqueous media under the UV light irradiation. Furthermore, the general applicability of the strategy was also demonstrated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1941-1952 [ABSTRACT FROM AUTHOR]

Highlights: [•] Double water compatible MIPs (DWC-MIPs) were prepared by RAFT polymerization. [•] DWC-MIPs has water compatible core with hydrophilic polymer brushes. [•] DWC-MIPs used as SPE sorbent for preconcentration four triazines with high efficiency. [•] The DWC-MIPs-SPE proves to be a highly effective cleanup and enrichment method. [Copyright &y& Elsevier]

Abstract: As a new class of synthetic receptors, molecularly imprinted polymers (MIPs) have shown great potential in many applications because of their good specific recognition ability, high stability, and easy preparation. The ultimate goal of molecular imprinting is to obtain MIPs that can be routinely used as alternatives to natural antibodies and receptors. However, the presently developed MIPs targeting small organic molecules mostly fail to show specific bindings in aqueous solutions, which is in sharp contrast to biological receptors and significantly limits their practical applications in such areas as biomimetic assays and sensors. Many efforts have been devoted to address this issue in the past two decades. In this feature article, I provide a detailed overview of the progress made in the development of water-compatible MIPs with an emphasis on our strategies to solve this challenging problem. Moreover, some still existing challenges and future prospects in this research area are also presented. [Copyright &y& Elsevier]

Water-compatible lanthanide-based Lewis acids for the efficient conversion of glucose and other carbohydrates to produce 5-hydroxymethylfurfural (HMF) were demonstrated in a biphasic reactor using sec-butyl phenol as the extracting solvent. The reaction of glucose dehydration to HMF was found to proceed under near-neutral conditions (pH = 5.5) and a moderately high yield of 42 mol % could be obtained. The combined catalytic system also showed effectiveness to convert other polysaccharides to HMF. Furthermore, the aqueous phase was recycled and used for multiple times without significant loss of catalytic performance. [ABSTRACT FROM AUTHOR]

Abstract: A new and efficient approach to obtaining molecularly imprinted polymers (MIPs) with both pure water-compatible (i.e., applicable in the pure aqueous environments) and stimuli-responsive binding properties is described, whose proof-of-principle is demonstrated by the facile modification of the preformed MIP microspheres via surface-initiated reversible addition–fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide (NIPAAm). The presence of poly(NIPAAm) (PNIPAAm) brushes on the obtained MIP microspheres was confirmed by FT-IR as well as the water dispersion and static contact angle experiments, and some quantitative information including the molecular weights and polydispersities of the grafted polymer brushes, the thickness of the polymer brush layers, and their grafting densities was provided. In addition, the binding properties of the ungrafted and grafted MIPs/NIPs in both methanol/water (4/1, v/v) and pure water solutions were also investigated. The introduction of PNIPAAm brushes onto the MIP microspheres has proven to significantly improve their surface hydrophilicity and impart stimuli-responsive properties to them, leading to their pure water-compatible and thermo-responsive binding properties. The application of the facile surface-grafting approach, together with the versatility of RAFT polymerization and the availability of many different functional monomers, makes the present methodology a general and promising way to prepare water-compatible and stimuli-responsive MIPs for a wide range of templates. [ABSTRACT FROM AUTHOR]

Abstract: Water-compatible pefloxacin-imprinted monoliths synthesized in a water-containing system were used for the selective extraction of fluoroquinolones (FQs). The MIP monolith was synthesized by using methacrylic acid as the functional monomer, di(ethylene glycol) dimethacrylate as a cross-linker and methanol–water (10:3, v/v) as the porogenic solvent. The ability of the derivated MIP for selective recognition of FQs (ciprofloxacin, difloxacin, danofloxacin and enrofloxacin) and quinolones (flumequine, and oxolinic acid) was evaluated. The derivated monolith showed high selectivity and was able to distinguish between FQs and quinolones. A simple rapid and sensitive method using polymer monolith microextraction (PMME) based on the MIP monolith combined with HPLC with fluorescence detection was developed for the determination of four FQs from milk samples. Owing to the unique porous structure and flow-through channels in the network skeleton of the MIP monolith, phosphate buffer diluted milk samples were directly supplied to PMME; allowing non-specific bound proteins and other biological matrix to be washed out, and FQs to be selectively enriched. The limit of detection of the method was 0.4–1.6ng/mL and recovery was 92.4–98.2% with relative standard deviations less than 5.9%. [Copyright &y& Elsevier]

Abstract: Water-compatible dendritic macrophotoinitiaors containing thioxanthone (TX), DAB-16-TX and DAB-64-TX, were synthesized by introducing a certain amount of TX moieties into the periphery of poly(propylene imine) (PPI). These photoinitiators have the similar UV–vis absorption to thioxanthone. Compared with DAB-16-TX, the fluorescence emission and the lifetime of the excited triplet state for TX in DAB-64-TX decreased, and polymerization rate of acrylamide (AAM) initiated by DAB-64-TX increased. With the increase of water content in the mixed solvent, the fluorescence emission intensity and the lifetime of the triplet state for TX of DAB-64-TX decreased, and the polymerization rate of AAM initiated by DAB-64-TX increased. [Copyright &y& Elsevier]

Preparation of molecularly imprinted polymers (MIPs) capable of directly and selectively recognizing small organic analytes in aqueous samples (particularly in the undiluted complex biological samples) is described. Such water-compatible MIPs can be readily obtained by the controlled grafting of appropriate hydrophilic polymer brushes onto the MIP particle surfaces. Two types of synthetic approaches (i.e., "two-step approach" and "one-step approach") for preparing complex biological sample-compatible hydrophilic fluorescent MIP nanoparticles and their applications for direct, selective, sensitive, and accurate optosensing of an antibiotic (i.e., tetracycline (Tc)) in the undiluted pure bovine/porcine serums are presented., (© 2021. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Herein, a novel method for molecularly imprinted polymers (MIPs) using methacrylic acid functionalized beta-cyclodextrin (MAA-β-CD) monomer is presented, which was designed as a potential water-compatible composite for the controlled release of atropine (ATP). The molecularly imprinted microspheres with pH-sensitive characteristics were fabricated using thermally-initiated precipitation polymerization, employing ATP as a template molecule. The effects of different compounds and concentrations of cross-linking agents were systematically investigated. Uniform microspheres were obtained when the ratio between ATP, MAA-β-CD, and trimethylolpropane trimethacrylate (TRIM) was 1:4:20 (mol/mol/mol) in polymerization system. The ATP loading equilibrium data was best suited to the Freundlich and Langmuir isotherm models. The in vitro drug release study was assessed under simulated oral administration conditions (pH 1.5 and 7.4). The potential usefulness of MIPs as drug delivery devices are much better than non-molecularly imprinted polymers (NIPs). The study shows that the prepared polymers are a pH stimuli-responsive system, which controlled the release of ATP, indicating the potential applications in the field of drug delivery. [ABSTRACT FROM AUTHOR]

A facile, general, and efficient approach to prepare hydrophilic hollow molecularly imprinted polymer (MIP) microparticles with photo- and thermoresponsive template binding and release behaviors in aqueous media is described, which includes the preparation of uniform "living" silica submicrospheres bearing surface atom transfer radical polymerization (ATRP)-initiating groups (i.e., alkyl halide groups) via a one-pot sol-gel method, their subsequent grafting of azobenzene (azo)-containing MIP shell and poly(N-isopropylacrylamide)-block-poly(2-hydroxyethyl methacrylate) (PNIPAAm-b-PHEMA) brushes via successive surface-initiated ATRP, and final removal of the silica core. The successful synthesis of such hydrophilic hollow MIP microparticles was confirmed with SEM, FT-IR, water dispersion stability, and static contact angle studies. They proved to show apparently higher template binding capacities than the corresponding solid ones and obvious photo- and thermoresponsive template binding properties in aqueous solutions. Moreover, their pronounced light- and temperature-controlled template release in aqueous media was also demonstrated. In particular, the introduction of PNIPAAm-b-PHEMA brushes onto hollow MIP microparticles imparted them with high surface hydrophilicity both below and above the lower critical solution temperature of PNIPAAm, which paves the way for their applications in such areas as controlled drug/chemical delivery and smart bioanalysis.

Novel water-compatible superparamagnetic molecularly imprinted polymers (M-MIPs) were prepared by coating superparamagnetic Fe3O4 nanoparticles with MIPs in a methanol-water reaction system. The M-MIPs were used for the selective adsorption and separation of vanillin from aqueous solution. The M-MIPs were characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), and scanning electron microscopy (SEM). Results indicated that a core-shell structure of M-MIPs was obtained by coating a layer of silica and MIPs on the surface of the Fe3O4 nanoparticles. The obtained M-MIPs possess a loose and porous structure and can be rapidly separated from the solution using a magnet. The adsorption experiments showed that the binding capacity of the M-MIPs was significantly higher than that of the superparamagnetic non-molecularly imprinted polymers (M-NIPs). Meanwhile, the adsorption of M-MIPs reached equilibrium within 100 min, and the apparent maximum adsorption quantity (Qmax) and dissociation constant (Kd) were 64.12 μmol g(-1) and 58.82 μmol L(-1), respectively. The Scatchard analysis showed that homogeneous binding sites were formed on the M-MIP surface. The recoveries of 83.39-95.58% were achieved when M-MIPs were used for the pre-concentration and selective separation of vanillin in spiked food samples. These results provided the possibility for the separation and enrichment of vanillin from complicated food matrices by M-MIPs.

A novel water-compatible macroporous molecularly imprinted film (MIF) has been developed for rapid, sensitive, and label-free detection of small molecule testosterone in urine. The MIF was synthesized by photo copolymerization of monomers (methacrylic acid [MAA] and 2-hydroxyethyl methacrylate [HEMA]), cross-linker (ethylene glycol dimethacrylate, EGDMA), and polystyrene nanoparticles (PS NPs) in combination with template testosterone molecules. The PS NPs and template molecules were subsequently removed to form an MIF with macroporous structures and the specific recognition sites of testosterone. Incubation of artificial urine and human urine on the MIF and the non-imprinted film (NIF), respectively, indicated undetectable nonspecific adsorption. Accordingly, the MIF was applied on a surface plasmon resonance (SPR) sensor for the detection of testosterone in phosphate-buffered saline (PBS) and artificial urine with a limit of detection (LOD) down to 10(-15)g/ml. To the best of our knowledge, the LOD is considered as one of the lowest among the SPR sensors for the detection of small molecules. The control experiments performed with analogue molecules such as progesterone and estradiol demonstrated the good selectivity of this MIF for sensing testosterone. Furthermore, this MIF-based SPR sensor shows high stability and reproducibility over 8months of storage at room temperature, which is more robust than protein-based biosensors., (Copyright © 2014 Elsevier Inc. All rights reserved.)