Novel Fluorescence Sensor Based on All-Inorganic Perovskite Quantum Dots Coated with Molecularly Imprinted Polymers for Highly Selective and Sensitive Detection of Omethoate.

All-inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, and I) have attracted considerable attention with superior electrical and photophysical properties. In this study, luminescent perovskite (CsPbBr3) quantum dots (QDs) as sensing elements combined with molecularly imprinted polymers (MIPs) are used for the detection of omethoate (OMT). The new MIPs@CsPbBr3 QDs were synthesized successfully through the imprinting technology with a sol-gel reaction. The fluorescence (FL) of the MIPs@CsPbBr3 QDs was quenched obviously on loading the MIPs with OMT, the linear range of OMT was from 50 to 400 ng/mL, and the detection limit was 18.8 ng/mL. The imprinting factor was 3.2, which indicated excellent specificity of the MIPs for the inorganic metal halide (IMH) perovskites. The novel composite possesses the outstanding FL capability of CsPbBr3 QDs and the high selectivity of molecular imprinting technology, which can convert the specific interactions between template and the imprinted cavities to apparent changes in the FL intensity. Hence, a selective and simple FL sensor for direct and fast detection of organophosphorus pesticide in vegetable and soil samples was developed here. The present work also illustrates the potential of IMH perovskites for sensor applications in biological and environmental detection.

A fluorescent glycosyl-imprinted polymer for pH and temperature regulated sensing of target glycopeptide antibiotic.

This paper demonstrates a new strategy for developing a fluorescent glycosyl-imprinted polymer for pH and temperature regulated sensing of target glycopeptide antibiotic. The technique provides amino modified Mn-doped ZnS QDs as fluorescent supports, 4-vinylphenylbronic acid as a covalent monomer, N-isopropyl acrylamide as a thermo-responsive monomer in combination with acrylamide as a non-covalent monomer, and glycosyl moiety of a glycopeptide antibiotic as a template to produce fluorescent molecularly imprinted polymer (FMIP) in aqueous solution. The FMIP can alter its functional moieties and structure with pH and temperature stimulation. This allows recognition of target molecules through control of pH and temperature. The fluorescence intensity of the FMIP was enhanced gradually as the concentration of telavancin increased, and showed selective recognition toward the target glycopeptide antibiotic preferentially among other antibiotics. Using the FMIP as a sensing material, good linear correlations were obtained over the concentration range of 3.0-300.0µg/L and with a low limit of detection of 1.0µg/L. The analysis results of telavancin in real samples were consistent with that obtained by liquid chromatography tandem mass spectrometry.

Molecularly Imprinted Polymer Nanogels Targeting C-Terminal of Angiotensin II for Lowering Blood Pressure of Rats by Oral Perfusion.

Over-expression of angiotensin II (Ang II) in bodies causes vasoconstriction and a subsequent increase in blood pressure. The present work proposes a novel technique of using an artificial receptor to reduce circulation of the excess Ang II in rats' bodies and subsequently lowering blood pressure of the rats by oral perfusion. A molecularly imprinted polymer nanogels (MIPNGs) receptor was prepared with the C-terminal pentapeptide of Ang II as the template in aqueous media, which served as a selective recognition element for Ang II. The resulting MIPNGs had good monodispersity, as measured by dynamic light scattering and further confirmed by transmission electron microscopy. The saturated adsorption capacity for angiotensin II of the MIPNGs reached 149.8 mg/g, and the yielding imprinting factor was 4.6. The MIPNGs displayed negligible toxicity and excellent cytocompatibility. The spontaneously hypertensive rats absorbed MIPNGs via oral perfusion at gradient producing a significant reduction in systolic blood pressure. Coupled with their biocompatibility and nontoxic characteristics, the MIPNGs offer the potential for neutralizing a wide range of biomacromolecules in vivo.

Preparation of core-shell magnetic molecular imprinted polymer with binary monomer for the fast and selective extraction of bisphenol A from milk.

In the current study, a new strategy for the extraction of bisphenol A (BPA) from milk has been employed by using surface-imprinted core-shell magnetic beads, prepared by the reversible addition-fragmentation chain transfer (RAFT) polymerization. In order to obtain highly selective recognition cavities, an enhanced imprinting method based on binary functional monomers, e.g. 4-vinylpyridine (4-VP) and ß-cyclodextrin (ß-CD), was chosen for BPA imprinting. The morphological and magnetic properties of the Fe3O4-MIP beads were characterized by Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FT-IR) Spectroscopy, Thermogravimetric Analysis (TGA), and Vibrating Sample Magnetometer (VSM). The characterization results suggested that MIP was synthesized evenly on Fe3O4-SiO2 surface. The adsorption experiments revealed that Fe3O4-MIPs showed better extraction capacity and selectivity toward BPA and its analogues than the non-imprinted polymers (NIPs). The saturation capacity of Fe3O4-MIP was 17.98mg/g. In milk samples, the present method displayed a lower the detection thresholds, down to 3.7µg/L. The recoveries of BPA in milk samples for three concentrations were found to be within 99.21%, 98.07% and 97.23%, respectively to three concentrations: 1.0µmol/L, 10.0mol/L, 100.0µmol/L. Thus, the MIPs can be used for remove BPA in milk samples.

Fabrication of a biomimetic adsorbent imprinted with a common specificity determinant for the removal of α- and ß-amanitin from plasma.

α-Amanitin and ß-amanitin are the main toxins of mushroom poisoning. The application of traditional non-selective adsorbents is not satisfactory in clinical treatment of amanita mushroom poisoning due to lack of specificity adsorption capability of these adsorbents toward amanitin toxins. In the current work, we introduce a novel molecularly imprinted biomimetic adsorbent based on a ligand specificity determinant through surface imprinted strategy. Owing to the expensive price of the amanitin sources, we selected a typical common moiety of α, ß-amanitin as specificity determinant to synthesize a template necessary for the preparation of molecularly imprinted polymers (MIPs). Computer simulation was used to initially select acidic methacrylic acid (MAA) and basic 4-vinyl pyridine (4-VP) together as functional monomers. The experiments further demonstrated that the synergistic interaction of MAA and 4-VP played a primary role in the recognition of α, ß-amanitin by MIPs. By means of batch and packed-bed column experiment and the hemocompatibility evaluation, the resultant biomimetic adsorbent has been proved to be capable of selectively removing α, ß-amanitin and possess good hemocompatibility. This novel adsorbent has great potential to find application in human plasma purification.

Antibody-free ultra-high performance liquid chromatography/tandem mass spectrometry measurement of angiotensin I and II using magnetic epitope-imprinted polymers.

The major challenges in measuring plasma renin activity (PRA) stem from the complexity of biological matrix, as well as from the instability and low circulating concentration of angiotensin. In this study, an ultra-high performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) based technique has been developed for the measurement of angiotensin using magnetically imprinted polymers for simultaneous enrichment of the precursor peptide angiotensin II (Ang II) and the upstream peptide precursor angiotensin I (Ang I). This technique involved surface graft imprinting in aqueous solutions using vinyl-modified nano-iron oxide as solid supports, the specificity determinant of Ang I and Ang II as the epitope, and methacrylic acid and N-t-butylacrylamide as functional monomers. The vinyl-modified nano-iron oxide acted as a magnetic separation media, and the molecularly imprinted shell provided analyte selectivity for the recognition of Ang I and Ang II. Selective enrichment of Ang I and Ang II was accomplished by the magnetically imprinted polymers, followed by a magnetic separation procedure and subsequent quantification by UPLC-MS/MS in the positive ionization mode with multiple reaction monitoring. Through the latter protocol, a low limit of detection could be realized, viz. 0.07ng/mL and 0.06ng/mL for Ang I and II, respectively, which was thoroughly validated for accuracy and reproducibility through analyzing Ang I and Ang II in human plasma samples.

Selective fluorescent sensing of α-amanitin in serum using carbon quantum dots-embedded specificity determinant imprinted polymers.

α-amanitin could make patients die of acute liver failure within a short time if suitable treatment is not provided in a timely fashion. This paper demonstrates a new strategy for direct detection of α-amanitin in serum using carbon quantum dots-embedded specificity determinant imprinted polymers. According to the structure of α-amanitin, we selected a proper moiety of α-amanitin as specificity determinant to synthesize template to prepare the MIPs. The computer simulation was used to screen out acidic methacrylic acid (MAA) and basic 4-vinyl pyridine (4-Vpy) together as functional monomers, and the experiments further proved that synergistic interaction of MAA and 4-Vpy was beneficial to enhance the recognition capability of MIPs for α-amanitin. Moreover, the fluorescence intensity showed good linear correlations with the concentration of α-amanitin from 0.05 to 4.0µgmL(-1). The detection limit for α-amanitin was 15ngmL(-1). The nanoparticles were employed to directly detect α-amanitin in serum without any pretreatment with recoveries of 97.8-100.9%.

Development of hybrid organic-inorganic surface imprinted Mn-doped ZnS QDs and their application as a sensing material for target proteins.

Applying molecular imprinting techniques to the surface of functionalized quantum dots (QDs) allows the preparation of molecularly imprinted polymers (MIPs) with accessible, surface exposed binding sites and excellent optical properties. This paper demonstrates a new strategy for producing such hybrid organic-inorganic imprinted Mn-doped ZnS QDs for specific recognition of bovine hemoglobin. The technique provides surface grafting imprinting in aqueous solutions using amino modified Mn-doped ZnS QDs as supports, acrylamide and methacrylic acid as functional monomers, γ-methacryloxypropyl trimethoxy silane as the grafting agent, and bovine hemoglobin as a template. The amino propyl functional monomer layer directs the selective occurrence of imprinting polymerization at the QDs surface through copolymerization of grafting agents with functional monomers, but also acts as an assistive monomer to drive the template into the formed polymer shells to create effective recognition sites. Using MIP-QDs composites as a fluorescence sensing material, trace amounts of bovine hemoglobin are signaled with high selectivity by emission intensity changes of Mn-doped ZnS QDs, which is embedded into the imprinted polymers.

Development of surface imprinted core-shell nanoparticles and their application in a solid-phase dispersion extraction matrix for methyl parathion.

Applying molecular imprinting techniques to the surface of functionalized SiO2 allows the preparation of molecularly imprinted polymers (MIPs) with accessible, high affinity and surface exposed binding sites. This paper demonstrates a new strategy for producing such hybrid organic-inorganic surface imprinted silica nanoparticles for specific recognition of methyl parathion. The technique provides surface grafting imprinting in chloroform using amino modified silica nanoparticles as supports, acrylamide as the functional monomer, γ-methacryloxypropyl trimethoxy silane as the grafting agent, and methyl parathion as a template. The amino propyl functional monomer layer directs the selective occurrence of imprinting polymerization at the silica surface through copolymerization of grafting agents with functional monomers, but also acts as an assistive monomer to drive the template into the formed polymer shells to create effective recognition sites. The resulting MIPs-SiO2 nanoparticles display three-dimensional core-shell architectures and large surface areas. The molecularly imprinted shell provides recognition sites for methyl parathion, with the materials exhibiting excellent performance for selecting the template. Using MIPs-SiO2 nanoparticles as a matrix of solid-phase dispersion extraction sorbents, trace amounts of methyl parathion are selectivity extracted from pear and green vegetable samples while simultaneously eliminating matrix interferences, attaining recoveries of 84.7-94.4% for the samples.

Recognition and neutralization of angiotensins I and II using an artificial nanogel receptor fabricated by ligand specificity determinant imprinting.

A nanogel combined with a molecularly imprinted polymer (MIP-nanogel) receptor was prepared using the specificity determinant as a template in aqueous media. The artificial receptor can serve as the selective recognition element for angiotensins I and II and a novel way to control hypertension was investigated.

An artificial receptor fabricated by target recognition determinant imprinting for selective capture of α-amanitin.

This is the first reported work of artificial α-amanitin receptors which are prepared using the design and synthesis of a template molecule based on an α-amanitin recognition determinant imprinting strategy. The resultant molecularly imprinted polymers (MIPs) are evaluated using high performance liquid chromatography (HPLC), binding experiment, nitrogen adsorption measurement, and solid-phase extraction. Experiment clearly demonstrates that the MIPs as the HPLC stationary phase can specifically recognize α-amanitin from analogues. The MIPs also successfully adsorb trace amounts of α-amanitin in spiked serum samples selectively pretreated and enriched through molecularly imprinted solid phase extraction. The limit of detection and recovery is 3.0 ng mL(-1) and 88.5-95.9%, respectively, for α-amanitin in serum samples. The high specific adsorption and excellent selectivity of the MIPs arises from imprinting effects related to the imprinting cavity of the polymeric matrix, the metal-coordination bond, and the hydrogen bond between the receptor and ligand.

Methyl parathion imprinted polymer nanoshell coated on the magnetic nanocore for selective recognition and fast adsorption and separation in soils.

Core-shell magnetic methyl parathion (MP) imprinted polymers (Fe3O4@MPIPs) were fabricated by a layer-by-layer self-assembly process. In order to take full advantage of the synergistic effect of hydrogen-binding interactions and π-π accumulation between host and guest for molecular recognition, methacrylic acid and 4-vinyl pyridine were chosen as co-functional monomers and their optimal proportion were investigated. The core-shell and crystalline structure, morphology and magnetic properties of Fe3O4@MPIPs were characterized. The MP-imprinted nanoshell was almost uniform and about 100nm thick. Binding experiments demonstrated that Fe3O4@MPIPs possessed excellent binding properties, including high adsorption capacity and specific recognition, as well as fast adsorption kinetics and a fast phase separation rate. The equilibration adsorption capacity reached up to 9.1mg/g, which was 12 times higher than that of magnetic non-imprinted polymers, while adsorption reached equilibrium within 5min at a concentration of 0.2mmol/L. Furthermore, Fe3O4@MPIPs successfully provided selective separation and removal of MP in soils with a recovery and detection limit of 81.1-87.0% and 5.2ng/g, respectively.

Selective room temperature phosphorescence sensing of target protein using Mn-doped ZnS QDs-embedded molecularly imprinted polymer.

The direct correlation between disease states and protein levels makes the sensitive, convenient, and precise detection of proteins the focus of scientific research. This paper demonstrates a new strategy for producing phosphorescent molecularly imprinted polymer (MIP) for specific recognition of a target protein. The technique provides surface graft imprinting in aqueous solutions using vinyl modified Mn-doped ZnS QDs as supports, methacrylic acid and acrylamide as functional monomers, and bovine hemoglobin as a template. The QDs act as antennae for recognition signal amplification and optical readout, and the MIP shell provides analyte selectivity and prevents interfering molecules from coming into contact with the QDs. The small particle sizes and the nontoxicity of the MIP-QDs composites allows for good dispersibility and stability in an aqueous solution. Under optimal conditions, good linear correlations were obtained for bovine hemoglobin over the concentration range from 1.0×10⁻7 to 5.0×10⁻6 mol L⁻¹ and with recoveries of 96.7-103.8% and 92.6-94.2% for urine and serum samples, respectively. The long lifetime of the MIP-QDs composites phosphorescence avoids interference due to autofluorescence and scattering of the biomatrix, facilitating composites' application for detection of bovine hemoglobin in biological fluids.

Binding characteristics of homogeneous molecularly imprinted polymers for acyclovir using an (acceptor-donor-donor)-(donor-acceptor-acceptor) hydrogen-bond strategy, and analytical applications for serum samples.

This paper demonstrates a novel approach to assembling homogeneous molecularly imprinted polymers (MIPs) based on mimicking multiple hydrogen bonds between nucleotide bases by preparing acyclovir (ACV) as a template and using coatings grafted on silica supports. (1)H NMR studies confirmed the AAD-DDA (A for acceptor, D for donor) hydrogen-bond array between template and functional monomer, while the resultant monodisperse molecularly imprinted microspheres (MIMs) were evaluated using a binding experiment, high performance liquid chromatography (HPLC), and solid phase extraction. The Langmuir isothermal model and the Langmuir-Freundlich isothermal model suggest that ACV-MIMs have more homogeneous binding sites than MIPs prepared through normal imprinting. In contrast to previous MIP-HPLC columns, there were no apparent tailings for the ACV peaks, and ACV-MIMs had excellent specific binding properties with a Ka peak of 3.44 × 10(5)M(-1). A complete baseline separation is obtained for ACV and structurally similar compounds. This work also successfully used MIMs as a specific sorbent for capturing ACV from serum samples. The detection limit and mean recovery of ACV was 1.8 ng/mL(-1) and 95.6%, respectively, for molecularly imprinted solid phase extraction coupled with HPLC. To our knowledge, this was the first example of MIPs using AAD-DDA hydrogen bonds.

Evaluation of diazepam-molecularly imprinted microspheres for the separation of diazepam and its main metabolite from body fluid samples.

Molecularly imprinted microspheres (MIMs) for the drug diazepam and its main metabolite (nordiazepam) were prepared and used to separate the two species from urine and serum samples via molecularly imprinted solid-phase extraction. The specific binding capacity for diazepam was determined to be 1.97 mg/g, resulting in an imprinting factor of 5.8. The MIMs exhibit highly selective binding affinity for tricyclic benzodiazepines. Water-acetonitrile-acetone mixtures were used as the washing solvent and resulted in complete baseline separation, with a recovery of >87% for diazepam and of 88% for nordiazepam. The limits of detection are 21.5 and 24.5 ng/mL, respectively.

A novel hydroquinidine imprinted microsphere using a chirality-matching N-acryloyl-L-phenylalanine monomer for recognition of cinchona alkaloids.

Using a combination of molecular imprinting technology and traditional chiral stationary phases, the synergistic effect between chiral monomer and chiral cavity of molecularly imprinted polymers in stereoselective recognition was investigated. We designed and synthesized an amino acid derivative to be used as a novel chiral functional monomer. Monodisperse molecularly imprinted core-shell microspheres using surface imprinting method on silica gel were prepared with hydroquinidine as the pseudo-template molecule for the resolution of cinchona alkaloids. The results showed a significant synergistic effect in stereoselective recognition, confirming our initial hypothesis. Furthermore, our computational simulation and experiments intensively support the hypothetical chiral recognition mechanism for the imprinted microspheres.

Room temperature phosphorescence sensor for Hg2+ based on Mn-doped ZnS quantum dots.

Mercury pollution is one of the most serious concerns to human health and the environment. The development of highly sensitive and selective sensors to detect toxic mercury ions has been the focus of scientific research. In this study, L-cysteine-capped Mn-doped ZnS quantum dots (QDs) have been synthesized and used for the room temperature phosphorescence detection of Hg2+. The phosphorescence of the Mn-doped ZnS QDs could be selectively quenched in the presence of Hg2+. Under optimal conditions, good linear correlations were obtained over the concentration range from 2.0 x 10(-8) mol/L to 4.5 x 10(-6) mol/L with a detection limit of 3.8 x 10(-9) mol/L. Additionally, the long lifetime of the phosphorescence of the Mn-doped ZnS QDs can avoid the interference of the autofluorescence and scattering light of the background, which facilitates their application in real samples. The possible quenching mechanism was examined by UV-vis absorption spectra and Rayleigh scattering spectra.

Novel molecularly imprinted microsphere using a single chiral monomer and chirality-matching (S)-ketoprofen template.

We designed and synthesized a cinchonine derivative to be used as a novel chiral monomer. It was employed in a dual role of functional monomer and cross-linking monomer, displaying multi-binding sites for the template (S)-ketoprofen. Monodisperse molecularly imprinted core-shell microspheres were prepared using surface imprinting method on silica gel. The results show a substantial synergistic effect in the enantioselective recognition, confirming our initial hypothesis. Computational simulation of the monomer and template pre-arrangement strongly supports our proposed chiral recognition mechanism for the imprinted microspheres.

Imprinted functionalized silica sol-gel for solid-phase extraction of triazolamin.

A triazolam-imprinted silica microsphere was prepared by combining a surface molecular-imprinting technique with the sol-gel process. The results illustrate that the triazolam-imprinted silica microspheres provided using γ-aminopropyltriethoxysilane and phenyltrimethoxysilane as monomers exhibited higher selectivity than those provided from γ-aminopropyltriethoxysilane and methyltriethoxysilane. In addition, the optimum affinity occurred when the molar ratio of γ-aminopropyltriethoxysilane, phenyltrimethoxysilane, and the template molecule was 4.2:4.7:0.6. Retention factor (k) and imprinting factor (IF) of triazolam on the imprinted and non-imprinted silica microsphere columns were characterized using high performance liquid chromatography (HPLC) with different mobile phases including methanol, acetonitrile, and water solutions. The molecular selectivity of the imprinted silica microspheres was also evaluated for triazolam and its analogue compounds in various mobile phases. The better results indicated that k and IF of triazolam on the imprinted silica microsphere column were 2.1 and 35, respectively, when using methanol/water (1/1, v/v) as the mobile phase. Finally, the imprinted silica was applied as a sorbent in solid-phase extraction (SPE), to selectively extract triazolam and its metabolite, α-hydroxytriazolam, from human urine samples. The limits of detection (LOD) for triazolam and α-hydroxytriazolam in urine samples were 30 ± 0.21 ng mL(-1) and 33 ± 0.26 ng mL(-1), respectively.

Recognition characteristics of molecularly imprinted microspheres for triazine herbicides using hydrogen-bond array strategy and their analytical applications for corn and soil samples.

The homogeneous molecularly imprinted microspheres (MIMs) based on a biologically inspired hydrogen-bond array were prepared using allobarbital as the novel functional monomer and divinylbenzene as the cross-linker. The host-guest binding characteristics were examined by molecular simulation and infrared spectroscopy. The resultant MIMs were evaluated using high performance liquid chromatography and solid-phase extraction. The results obtained demonstrate that the good imprinting effect and the excellent selectivity of MIMs are mainly due to the interaction involving the formation of three-point hydrogen bond between host and guest. The complete baseline separation was obtained for five triazine analogues and a metabolite on the MIM HPLC column. The MIMs were further successfully used as a specific sorbent for selective extraction of simetryne from corn and soil samples by molecularly imprinted solid phase extraction. Detection limits and recoveries were 5.8 µg/kg and 0.14 µg/kg and 87.4-105% and 94.6-101% for simetryne in corn and soil sample, respectively.