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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]

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.