Specific Recognition Capability Research Articles

Synthesis of magnetic green nanoparticle – Molecular imprinted polymers with emerging contaminants templates

Iron nanoparticles synthesis by an oxidation reaction is the traditional method to obtain these nanoparticles. Nowadays, new synthesis methods are being investigated to promote green chemistry. In this work, nanoparticles were performed from eucalyptus extracts and they were synthesized using a green chemistry method. Eucalyptus extracts is a material abundant in Galicia forests, so it makes them very attractive for economic, availability and reuse issues. Both types of nanoparticles were synthesized with molecular imprinted polymers (MIPs). These are materials with specific and selective analyte recognition capabilities. However, when the available sample volume in very low, the handling of polymer in liquid matrixes is complex and, for this reason, polymers were prepared attached on magnetic nanoparticles, to combine the pre-concentration capability of MIPs and the magnetic capability of nanoparticles. Green nanoparticles (GNPs) present higher adsorption capacities than chemical nanoparticles (CNP) due to the organic material which is present in the extract. The adsorption capacity with green nanoparticles was increased by more than 100 % in all cases, in relation to the adsorption value of the chemical nanoparticles. Adsorption kinetic mechanisms is suitable descripted by pseudo – second order model and thermodynamics results show Langmuir isotherm is suitable to explain the adsorption of interest molecules.

Study of near-infrared light-induced excitation of upconversion nanoparticles as a vector for non-viral DNA delivery.

Clinical requirements have necessitated the development of biomedical nanomaterials that can be implanted into tissues or bodies. Physiological regulation can be achieved in these nanomaterials through external light. The combination of nanomaterials with infrared optics can be termed optogenetics. The low autofluorescence of upconversion nanoparticles (UCNPs) has several applications in the biological field. For optogenetics applications, UCNPs with high fluorescence performance and photostability can solve the penetration depth problem. NaYF4:Yb,Tm nanocrystals with controllable sizes, shapes, and compositions were synthesized using a rapid coprecipitation method in organic solvent. UCNPs using single crystal nanoparticles provide higher chemical stability than those using amorphous phase. However, because UCNPs are usually capped with hydrophobic ligands, it is particularly important to prepare biocompatible UCNPs with specific molecular recognition capabilities. Surface modification and subsequent functionalization are essential for the application of inorganic nanomaterials in the biological environment and are arousing increasing research interest. Due to the high biocompatibility and high loading of materials, mesoporous silica and amine groups were selected as the best candidates. Expression of plasmid DNA in vivo and transfection efficiency were determined by fluorescence microscopy and flow cytometry. The MTT assay was used to evaluate the particle biocompatibility; the results showed that UCNP@mSiO2 has great biocompatibility. Additionally, at neutral pH, the cell surface is negatively charged. Therefore, the surface is functionalized with amino groups and can be electrostatically bound to DNA. Finally, UCNP@mSiO2-NH2 as a vector was applied in live cells by loading DNA; according to the results, DNA-UCNPs were successfully transfected in the primary cells, and NaYF4:Yb,Tm@mSiO2-NH2-DNA were observed to have good transfection efficiency by flow cytometry. It is expected that this work will provide a different method from the traditional adenovirus method and improve the immune response and side effects caused by adenovirus.

Electrochemical Determination of Vitamin D3 in Pharmaceutical Products by Using Boron Doped Diamond Electrode

AbstractA sensitive square‐wave voltammetry method was developed to determine cholecalciferol (vitamin D3) in pharmaceutical products at boron‐doped diamond electrode as a working electrode. Vitamin D3 provided a well‐defined voltammetric peak at around +1.00 V (vs. Ag/AgCl, 3.5 mol dm−3) in 0.02 mol dm−3 Britton‐Robinson buffer pH 5.0 prepared in 50 % ethanol. The influence of various factors such as type and pH of the supporting electrolyte, scan rate and square‐wave parameters were studied and optimized. Under optimum conditions, the oxidation peak current increased linearly with the concentration of vitamin D3 over the range of 2 to 200 μmol dm−3. The calculated limit of detection and limit of quantitation were 0.17 μmol dm−3 and 0.51 μmol dm−3, respectively. The boron‐doped diamond electrode exhibited specific recognition capability for cholecalciferol amongst possible interferences, and the determination of vitamin D3 was possible in samples such as commercial pharmaceutical products without complicated sample pretreatments.

Molecularly Imprinted Phase-Change Microcapsule System for Bifunctional Applications in Waste Heat Recovery and Targeted Pollutant Removal.

An innovative design of a molecularly imprinted phase-change microcapsule (MIM) system for bifunctional applications in waste heat recovery and targeted pollutant removal was reported in this work. This molecularly imprinted system was successfully constructed by encapsulating n-eicosane with a SiO2 base shell through emulsion-templated interfacial polycondensation and then coating a molecularly imprinted polymeric layer with bisphenol A (BPA) as a template molecule through surface free-radical polymerization. The morphology, microstructure, and chemical structure of the resultant molecularly imprinted phase-change microcapsules (MIMs) were characterized, and their phase-change behavior, thermal energy-storage performance, and selective adsorption capability were investigated intensively. The MIMs developed in this study achieved an outstanding latent heat-storage capability with a high capacity more than 165 J/g and also showed an excellent phase-change reliability with a very small fluctuation in phase-change temperatures and enthalpies after 500 thermal cycles. Moreover, the MIMs also presented a high thermal stability over 200 °C and good shape stability up to 120 °C. Most of all, an effective specific recognition capability and high recognition efficiency were achieved for the MIMs due to the formation of BPA-molecular imprinting sites on their surface. As a result, the MIMs exhibited good adsorption selectivity toward the BPA molecules and satisfactory reusability for targeted removal of BPA with a removal efficiency of 61.7% after 10 cycles of the rebinding-elution procedure. In view of a smart combination of thermal energy-storage and selective adsorption functions, the MIMs developed in this study demonstrate a great potential in applications for waste heat recovery and targeted pollutant removal of industrial and domestic wastewaters.

Preparation of monodisperse magnetic surface molecularly imprinted polymers for selective recognition of lincomycin hydrochloride in milk

Monodisperse magnetic surface molecularly imprinted polymers (M-MIPs) with a specificity for lincomycin hydrochloride (LIN) were successfully prepared using surface-initiated atom transfer radical polymerization on the monodisperse magnetic polymer (vinylbenzylchloride/divinylbenzene) (Fe3O4/PVBC/DVB) with LIN as a template molecule and 4-vinyl pyridine as the functional monomer. The Fe3O4 magnetic nanoparticles embedded itself in the micropores of polymer (PVBC/DVB) by reversibly swelling adsorption method in which the pores of the polymer are swollen by the solvent, and then the Fe3O4 magnetic nanoparticles enter the pores, and as the solvent evaporates the pores of the polymer back to their original size, and Fe3O4 magnetic nanoparticles are left in the pores. The composition and magnetic properties of the polymer were characterized using scanning elemental microscopy analysis, X-ray diffraction, Surface element analysis and vibrating sample magnetometer analysis. The results of this study showed that the M-MIPs had good specific recognition ability for LIN. The imprinting factor is 3.72. The specific recognition capability of the polymers was affirmed by high performance liquid chromatography analysis. The spiked recovery was 94.3%–98.2% with RSD ≤ 3.7%, and the minimum detection limit is 15.0 ng/g (S/N = 3) indicating that this material has application value in the pretreatment of complex samples.

An aptamer-based four-color fluorometic method for simultaneous determination and imaging of alpha-fetoprotein, vascular endothelial growth factor-165, carcinoembryonic antigen and human epidermal growth factor receptor 2 in living cells.

The extraordinary fluorescence quenching capability of graphene oxide (GO) was coupled to the specific recognition capability of aptamers to design a four-color fluorescent nanoprobe for multiplexed detection and imaging of tumor-associated proteins in living cells. Specifically, alpha-fetoprotein (AFP), vascular endothelial growth factor-165 (VEGF165), carcinoembryonic antigen (CEA), and human epidermal growth factor receptor 2 (HER2) were detected. Due to strong π interaction, the fluorescence of labeled aptamers is quenched by GO. Four fluorophore-labeled aptamers that bind the tumor-associated proteins were adsorbed on GO to form the four-color nanoprobe with quenched fluorescence. The nanoprobes were internalized into cells via endocytosis, where the aptamer/GO nanoprobes bind the intracellular tumor-associated proteins. The aptamer-protein complexes thus formed detach from GO, and fluorescence recovers. Each analyte has its typical color (AFP: blue; VEGF165: green; CEA: yellow; HER2: red). As a result, simultaneous detection and imaging of multiple tumor-associated proteins in living cells were achieved. This nanoprobe has a fast response and is highly specific and biocompatible. The linear ranges for AFP, VEGF165, CEA, and HER2 are 0.8nM-160nM, 0.5nM-100nM, 1.0nM-200nM, and 1.2nM-240nM, respectively. Detection limits were 0.45nM for AFP, 0.30nM for VEGF165, 0.62nM for CEA, and 0.96nM for HER2. The probe allows for a fast distinction between tumor cells and normal cells via imaging. Graphical abstract Schematic presentation of the development of a four-color fluorometic method based on aptamer and graphene oxide for simultaneous detection and imaging of alpha-fetoprotein, vascular endothelial growth factor-165, carcinoembryonic antigen and human epidermal growth factor receptor 2 in living cells.

In Vitro Selection of a DNA Aptamer by Cell-SELEX as a Molecular Probe for Cervical Cancer Recognition and Imaging.

Aptamers have become the most promising recognition reagents in terms of early diagnosis and effective treatment of cancers. In this study, using cervical cancer as a model, we have identified a DNA aptamer specifically binding to cervical cancer cells with high affinity using the cell-SELEX (systematic evolution of ligands by exponential enrichment) method, in which a negative selection was carried out using normal epithelial cells as control. The binding abilities of 6 selected truncated aptamers were determined by laser confocal fluorescence microscopy and flow cytometry, while most of them only recognize the target cells and do not bind the control cells, and the aptamer C-9S with 51-mer shows the best binding affinity to Ca Ski cells (target cells) with a dissociation constant value of 19.3 ± 2.9nM. Moreover, at physiological temperature, C-9S remains its specific recognition capability to Ca Ski cells as well. Meanwhile, C-9S shows a similar binding ability to another cervical cancer cells (HeLa). Therefore, on the basis of its excellent targeting properties and inherent functional versatility of aptamer, C-9S holds great potential to be a molecular probe for early detection, in vivo imaging, and targeted delivery for further researches in cancer.

Preparation of magnetic ion imprinted polymer with waste beer yeast as functional monomer for Cd(ii) adsorption and detection.

In this work, a magnetic ion imprinted polymer (MIIP) with specific recognition capability toward cadmium was prepared by a sol–gel method using waste beer yeast, which is a macromolecule biomass, as a functional monomer. The obtained Cd(ii)-MIIP was characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and adsorption experiments. Then, a MIIP adsorbent based magnetic solid phase extraction (MSPE)-graphite furnace atomic absorption (GFAA) method was established to analyze the cadmium content in food and environmental samples. The maximum cadmium adsorption capacities by the MIIP and magnetic non-imprinted polymer (MNIP) were 62.74 and 32.38 mg g−1, respectively. The absorption by the MIIP was fitted using a pseudo-second-order kinetic model. The Cd(ii)-MIIP demonstrated superior absorption capability for selective removal cadmium. The recovery rate of the MIIP was 90.7% after four adsorption–desorption cycles. The calculated Cd(ii) detection limit (S/N = 3) was 0.18 μg L−1 with the relative standard deviation (RSD) equal to ∼3.5% for 10 μg L−1 of Cd(ii) standard solution. Our proposed method was successfully used in detecting Cd(ii) in aqueous samples. The results obtained in this work suggest that the Cd(ii)-MIIPs might be promising adsorbents to remove harmful cadmium ions from aqueous samples.

Pickering emulsion-based molecular imprinting

Due to the specific recognition ability of the target molecules, molecularly imprinted polymers (MIPs) have been widely used in many fields. So far, the research in molecular imprinting mainly focused on two aspects: (1) synthesis of MIPs with more functions; (2) expanding applications of the traditional MIPs, especially for MIPs synthesized by precipitation polymerization. To address these points, our group recently introduced a new insight in molecular imprinting based on Pickering emulsion: (1) Pickering emulsion polymerization could be used to the synthesize water-compatible MIP spheres with well-controlled structures; (2) MIP nano/microparticles stabilized emulsions were introduced to molecular imprinting to endow the MIP particles with more functions, or to create new interfacial binding or catalytic systems for MIP nano/microparticles. It is noted that, although the first molecular imprinting in Pickering emulsion has been presented for only a few years, the publications in this field increased very fast. In this review, we summarized the synthesis of MIP spheres via Pickering emulsion polymerization, and discussed the advantages and limitations of this synthesis method. Due to the unique properties of the particle stabilized emulsion, the imprinted systems offered several advantages to the resulted MIP spheres, and which could be further utilized to solve the long-tern challenges in imprinting of small molecules: (1) well-designed hierarchical structures (surface nano-pores from the particle stabilizers and accessible molecular binding cavities from the templates); (2) group recognition of a series of chemicals with a similar moiety (epitope imprinting); and (3) specific recognition capability in aqueous conditions because of the hydrophilic surface of the MIPs. Moreover, for imprinting biomacromolecules and other large templates (virus particles, bacteria and animal cells), Pickering emulsion was also particularly interesting, because the templates themselves could be directly used as solid stabilizers to synthesis Pickering emulsion, and thus created accessible surface imprinted sites for the recognition. In this review, we also demonstrated that MIP nano/microparticles stabilized emulsions were promising interfacial systems in molecular imprinting. On one hand, this emulsion could be utilized for the fabrication of functional materials with pre-designed recognition ability towards the target molecules. As examples, the Janus MIP particles, which displayed attractive abilities as self-propelled transporters for controlled drug delivery, could be prepared via a wax-water Pickering emulsion. Multifunctional colloidosomes, which showed both specific molecular recognition of the MIP nanoparticles and dose-dependent fluorescence response to fructose, could be synthesized by using W/O Pickering emulsions stabilized by clickable nanoparticles: Alkyne-coated MIP nanoparticles and azide-modified nanoparticles, followed by an interfacial click reaction. On the other hand, the introduction of Pickering emulsion expanded tha application environment of the traditional MIP nano/microparticles to a oil-water interface. For example, MIP microgel stabilized Pickering emulsions with the capability to catalyze the formation of disulfide bonds in peptides at the O/W interface has been reported recently. These works system will greatly promote the application of molecular imprinting in various fields such as organic synthesis, disease diagnosis, proteomics and bio-imaging Moreover, we discussed the prospects of the applications of molecular imprinting in Pickering emulsion in a near future, (1) uniform MIP spheres should be fabricated by optimizing the emulsion systems and choosing suitable reactors; (2) stable Pickering emulsion systems should be developed for biomacromolecular imprinting, such as proteins, micro organisms and human cells; (3) MIP nano/microparticles prepared by Pickering emulsion should be designed for immunoassay, biomedicine, environmental governance and chemical catalysis. As a summary, we believed that molecular imprinting in Pickering emulsion provided a facile synthetic approach for producing new functional materials, as well as an interfacial binding or catalytic environment for appilication of the traditional MIP nano/microparticles. All these works show great potential in clinical pathogenic screening, noninvasive detection and drug delivery.

Dual-Aptamer-Conjugated Molecular Modulator for Detecting Bioactive Metal Ions and Inhibiting Metal-Mediated Protein Aggregation.

Bioactive metal ions play important roles in both physiological and pathological processes. Developing biosensing probes for bioactive metal ion detection can contribute to fields including disease diagnosis and therapy and studying the mechanisms of biological activities. In this work, we designed a dual-aptamer-conjugated molecular modulator that can detect Zn2+ and further inhibit Zn2+-induced amyloid β (Aβ) aggregation. The molecular modulator is able to selectively target Aβ species and block Zn2+ due to the specific recognition capability of aptamers. With the binding of Zn2+, the fluorescence signal of this molecular modulator is restored, thus allowing for Zn2+ detection. More importantly, this molecular modulator can inhibit the generation of Zn2+-triggered Aβ aggregates due to the trapping of Zn2+ around Aβ species. Circular dichroism measurements reveal that the dual-aptamer-conjugated molecular modulator prevents the conformational transition of the Aβ monomer from a random coil to a β-sheet. Furthermore, after treating with the molecular modulator, no Aβ aggregate is observed in the Aβ solution with added Zn2+, demonstrating that Aβ aggregation is successfully inhibited by this molecular modulator. Our approach provides a promising tool for detecting bioactive metal ions and studying the molecular mechanisms behind life activities.

Solid-phase extraction of aflatoxins using a nanosorbent consisting of a magnetized nanoporous carbon core coated with a molecularly imprinted polymer.

A core consisting of nanoporous carbon (MNPC) and magnetized with Co3O4 was coated with a molecularly imprinted polymer (MIP) by atom transfer radical precipitation polymerization. Ethyl 3-coumarincarboxylate was used as a pseudo-template to give a MIP that has a fairly specific recognition capability for aflatoxins. Batch rebinding studies were carried out to determine the specific adsorption equilibrium and specific recognition. Extraction is achieved in a single step by mixing and vortexing the sample extract with the Co-MNPC@MIP. The loaded nanosorbent was then magnetically separated and eluted with acetonitrile/water (6/4, v/v). The aflatoxins were then quantified by HPLC. Under optimal conditions, the detection limits for aflatoxins typically are 0.05-0.07ngmL-1, recoveries from spiked corn are found to be 75.1 to 99.4%, and relative standard deviations range from 1.7 to 5.1 (n= 6). Graphical abstract Poly(methacrylic acid) was imprinted with the pseudo-template ethyl 3-coumarincarboxylate by atom transfer radical precipitation polymerization on the surface of cobalt-derived magnetic nanoporous carbon (Co-MNPC). This nanosorbent was used for the magnetic solid phase extraction of aflatoxins, followed by HPLC analysis.

Preparation of thiamphenicol magnetic surface molecularly imprinted polymers for its selective recognition of thiamphenicol in milk samples

A magnetic surface molecularly imprinted polymers (MMIPs) with thiamphenicol (TAP) specificity was prepared by using thiamphenicol as a template molecule, methacrylic acid (MAA) as the functional monomer, and silicon dioxide-coated ferriferous oxide (Fe3O4 @ SiO2) as the magnetic carrier. The composition, thermal stability, and magnetic properties of the polymer were characterized by fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and vibration sample magnetometer (VSM). The results of these studies show that the imprinted polymer layer was successfully applied to the surface of the Fe3O4@SiO2 magnetic material, and that the imprinted particles retain desirable magnetic properties. The MMIPs were applied to extract and quantify thiamphenicol in milk samples. The specific recognition capability of the polymers was affirmed by high performance liquid chromatographic (HPLC) analysis, establishing the limit of detection (LOD) as 10 µg/L and a recovery rate of greater than 85%. A rapid and selective method was established to quantify TAP using MMIPs as a sorbent. The method was used to detect thiamphenicol in milk samples with satisfactory results.

Selective detection of chloramphenicol based on molecularly imprinted solid-phase extraction in seawater from Jiaozhou Bay, China

This study highlights an efficient sample pre-treatment method for preconcentration and detection of chloramphenicol in marine water using molecularly imprinted solid-phase extraction (MISPE). Chloramphenicol molecularly imprinted microspheres were prepared and evaluated on the base of morphology, capacity and selectivity. The imprinted microspheres exhibited specific recognition and high retention capability to chloramphenicol and were applied as special solid-phase extraction adsorbents. An off-line MISPE protocol has been optimized and a creative analytical method coupled to HPLC-DAD was successfully developed for the cleanup and determination of chloramphenicol in seawater samples. Method performance was satisfactory with recoveries ranging from 81 to 90% and relative standard deviation (RSD) was <4.93% (n = 3). Accuracy of the method was assessed at three spiking concentration levels and the limit of detection was 5 ng L−1. Finally, five seawater samples from Jiaozhou Bay of China were determined and the results showed that there was no chloramphenicol detected.

Hierarchical MgFe-layered double hydroxide microsphere/graphene composite for simultaneous electrochemical determination of trace Pb(II) and Cd(II)

Heavy metal contamination has been demonstrated to possess the severe threats toward the whole ecosystems and public security even at trace levels. Therefore, it is essential to exploit an ultrasensitive technique to determine the levels of heavy metal ions. In this work, hierarchical MgFe-layered double hydroxide (MgFe-LDH) microspheres have been successfully immobilized on the graphene nanosheets surface via a facile one-step hydrothermal route. Benefiting from the synergistic effects associated with high specific surface area, strong affinity of hierarchical MgFe-LDH architecture toward heavy metal ions, good electrical conductivity and effective electron transfer efficiency of graphene, the resulting composite (denoted as MgFe-LDH/graphene) is explored as an electrochemical sensor for simultaneous detection of Pb(II) and Cd(II) in aqueous medium. As a consequence, MgFe-LDH/graphene modified electrode exhibits low detection limit of 5.9 nM for Cd(II) and 2.7 nM for Pb(II), which are dramatically lower than the respective values of 3 ppb (27 nM) and 10 ppb (48 nM) in domestic water permitted by the World Health Organization (WHO). Meaningfully, the proposed electrochemical sensor shows specific recognition capability to Pb(II) and Cd(II), excellent reproducibility in repetitive measurements as well as feasibility in real water analysis.

Preparation of magnetic surface molecularly imprinted polymers for melamine and its application in milk samples

By using melamine (MEL) as the template molecule, magnetic surface molecularly imprinted polymers (MMIPs) were prepared. Methacrylic acid (MAA) was chosen as the functional monomer, and ethyleneglycol dimethacrylate (EGDMA) was chosen as the cross-linker, and Fe3O4@SiO2 was used as the magnetic supporter. Transmission electron microscope (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) analysis and a vibrating sample magnetometer (VSM) were used to characterize the polymers. An imprinted polymer layer was found on the surface of the Fe3O4@SiO2 nanomaterials. MMIPs were applied to extract and enrich melamine in milk samples. The specific recognition capability of the material was confirmed by high performance liquid chromatographic (HPLC) analysis. Thus, a simple and selective method was successfully established using MMIPs as sorbents to detect melamine in milk with satisfactory results.

Highly fluorescent carbon dots from Pseudo-stem of banana plant: Applications as nanosensor and bio-imaging agents

Carbon dots (CDs) with 48% quantum yield (QY) were synthesized by simple hydrothermal treatment using Pseudo-stem of banana plant as carbon source. As synthesized CDs were characterized using UV–vis, fluorescence, dynamic light scattering (DLS), Fourier transform infrared (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS) and High resolution transmission electron microscopic (HRTEM) techniques. A fluorescent nanosensor which exhibits highly specific recognition capability towards Fe3+ over other competing metal ions has been reported. CD exhibits fluorescent “turn-off” sensing nature with high selectivity towards Fe3+ with a detection limit as low as 6.4nM and “turn-on” property towards S2O32− anion. The biocompatibility of CDs was revealed from the cytotoxicity studies on cancerous cells (HeLa, MCF-7 (Michigan Cancer Foundation-7)) and was employed as fluorescent probes for multi-coloured (blue, green and red) imaging of HeLa and MCF-7 cells. Due to the bright fluorescence, water solubility, high photo-stability, low toxicity, cell-membrane permeability and good biocompatibility, as-prepared carbon nanodots are demonstrated to be excellent probe as bio-imaging agent.

Silver nanoclusters with enhanced fluorescence and specific ion recognition capability triggered by alcohol solvents: a highly selective fluorimetric strategy for detecting iodide ions in urine.

Alcohol solvents especially isopropanol were demonstrated for the first time to endow silver nanoclusters (AgNCs) in water with dramatically enhanced red fluorescence. More importantly, the specific iodide recognition capability of the AgNCs could thus be obtained towards a highly selective fluorimetric assay for detecting iodide ions in urine.

Construction of stable core–shell imprinted Ag-(poly-o-phenylenediamine)/CoFe2O4 photocatalyst endowed with the specific recognition capability for selective photodegradation of ciprofloxacin

The stable core–shell imprinted Ag-POPD/CoFe2O4 photocatalyst not only possessed high photocatalytic activity, but also exhibited the superior specific recognition capability for selective photodegradation of CIP.

Development of magnetic molecularly imprinted polymers with double templates for the rapid and selective determination of amphenicol antibiotics in water, blood, and egg samples

A magnetic mesoporous dual-template molecularly imprinted polymer (Fe3O4@mSiO2 @DMIP) with a specific recognition capability for chloramphenicol (CAP) and florfenicol (FF) was synthesised. CAP and FF were used as dual-template molecules, α-methacrylic acid and Fe3O4@mSiO2@-CHCH2 as dual functional monomers, and ethylene glycol dimethyl methacrylate as a crosslinking agent. For comparison, a magnetic mesoporous non-molecularly imprinted polymer (Fe3O4@mSiO2@NIP) was also prepared using the same synthesis procedure, but without the dual templates. The prepared polymers were characterised using scanning electron microscopy, Fourier-transform infrared spectroscopy and adsorption experiments. Results indicated that both the Fe3O4@mSiO2@DMIP and the Fe3O4@mSiO2 @NIP were microspherical nanoparticles, and the surface of the Fe3O4@mSiO2@DMIP was rougher than that of the Fe3O4@mSiO2@NIP. In addition, the prepared Fe3O4@mSiO2@DMIP possessed a higher adsorption capacity and better selectivity for CAP and FF than the Fe3O4@mSiO2@NIP. The maximum static adsorption capacities of the Fe3O4@mSiO2@ DMIP for CAP and FF were 146.5 and 190.1mgg−1, respectively, whereas those of the Fe3O4@mSiO2 @NIP were 50.0 and 44.0mgg−1, respectively. The obtained Fe3O4@mSiO2@DMIP particles were applied as a magnetic solid-phase extraction sorbent for the rapid and selective extraction of CAP, FF, and thiamphenicol (TAP) in water, chicken blood and egg samples. The method of magnetic molecularly imprinted solid-phase extraction (M-MISPE) coupled to high-performance liquid chromatography with UV detection (HPLC-UV) was conducted to detect CAP, FF, and TAP. The limits of detection for CAP, FF, and TAP were 0.16, 0.08, and 0.08μgkg−1, respectively. The average recovery and precision values for the spiked water, chicken blood, and egg samples ranged from 88.3% to 99.1% and 2.7% to 7.9%, respectively. Given its rapidity, selectivity, and sensitivity, the developed method of M-MISPE coupled to HPLC–UV detection has good application prospects in environmental, biological, and food samples.

A Modular Bioplatform Based on a Versatile Supramolecular Multienzyme Complex Directly Attached to Graphene.

Developing generic strategies for building adaptable or multifunctional bioplatforms is challenging, in particular because protein immobilization onto surfaces often causes loss of protein function and because multifunctionality usually necessitates specific combinations of heterogeneous elements. Here, we introduce a generic, modular bioplatform construction strategy that uses cage-like supramolecular multienzyme complexes as highly adaptable building blocks immobilized directly and noncovalently on graphene. Thermoplasma acidophilum dihydrolipoyl acyltransferase (E2) supramolecular complexes organize as a monolayer or can be controllably transferred onto graphene, preserving their supramolecular form with specific molecular recognition capability and capacity for engineering multifunctionality. This E2-graphene platform can bind enzymes (here, E1, E2's physiological partner) without loss of enzyme function; in this test case, E1 catalytic activity was detected on E2-graphene over 6 orders of magnitude in substrate concentration. The E2-graphene platform can be multiplexed via patterned cotransfer of differently modified E2 complexes. As the E2 complexes are robust and highly customizable, E2-graphene is a platform onto which multiple functionalities can be built.