Detection of λ-cyhalothrin by a core-shell spherical SiO2-based surface thin fluorescent molecularly imprinted polymer film.

A fluorescent core-shell molecularly imprinted polymer based on the surface of SiO2 beads was synthesized and its application in the fluorescence detection of ultra-trace λ-cyhalothrin (LC) was investigated. The shell was prepared by copolymerization of acrylamide with allyl fluorescein in the presence of LC to form recognition sites. The experimental results showed that the thin fluorescent molecularly imprinted polymer (FMIP) film exhibited better selective recognition ability than fluorescent molecularly non-imprinted polymer (FNIP). A new nonlinear relationship between quenching rate and concentration was found in this work. In addition, the nonlinear relationship allowed a lower concentration range of 0-5.0 nM to be described by the Stern-Volmer equation with a correlation coefficient of 0.9929. The experiment results revealed that the SiO2@FMIP was satisfactory as a recognition element for determination of LC in soda water samples. Therefore this study demonstrated the potential of MIP for the recognition and detection of LC in food.

Selective solid-phase extraction of artificial chemicals from milk samples using multiple-template surface molecularly imprinted polymers.

A novel multiple-template surface molecularly imprinted polymer (MTMIP) was synthesized using ofloxacin and 17ß-estradiol as templates and modified monodispersed poly(glycidylmethacrylate-co-ethylene dimethacrylate) (PGMA/EDMA ) beads as the support material. Static adsorption, solid-phase extraction and high-performance liquid chromatography were performed to investigate the adsorption properties and selective recognition characteristics of the polymer templates and their structural analogs. The maximum binding capacities of ofloxacin and 17ß-estradiol on the MTMIP were 9.0 and 6.6 mg/g, respectively. Compared with the corresponding nonimprinted polymer, the MTMIP exhibited a much higher adsorption performance and selectivity toward three quinolones and three estrogens, which are common drug residues in food. The MTMIP served as a simple and effective pretreatment method and could be successfully applied to the simultaneous analysis of multiple target components in complex samples. Furthermore, the MTMIP may find useful applications as a solid-phase absorbent in the simultaneous determination of trace quinolones and estrogens in milk samples, as the recoveries were in the range 77.6-98.0%.

A novel surface molecularly imprinted polymer based on the natural biological macromolecule sporopollenin for the specific and efficient adsorption of resveratrol from Polygonum cuspidatum extracts.

Sporopollenin is a natural biological macromolecule consisting of highly cross-linked carbon, hydrogen, and oxygen atoms, with a highly porous structure and multifunctional groups. In this work, a novel surface molecularly imprinted polymer based on magnetically aminated cattail sporopollenin (MACSp-SMIP) was prepared for the specific and efficient adsorption of resveratrol, with the aim of purifying resveratrol from Polygonum cuspidatum extracts. MACSp-SMIP was found to have a porous structure covered with the multi-layered sponge-like imprinted polymers. MACSp-SMIP had a high adsorption capacity for resveratrol (65.77 mg·g-1) and excellent selectivity (imprinting factor 5.64). The adsorption of resveratrol by MACSp-SMIP was a homogeneous diffusion dominated by chemical adsorption with three stages of external diffusion, internal diffusion, and micropore diffusion. MACSp-SMIP was used as an adsorbent in molecularly imprinted solid-phase extraction for the purification of resveratrol from P. cuspidatum extracts, achieving a resveratrol recovery of 94.33 % and a purity of 76.67 % in the final products. MACSp-SMIP maintained a satisfactory recovery of resveratrol (88.18 %) after six cycles. Overall, this work developed a promising biological macromolecule-based adsorbent MACSp-SMIP for the specific and efficient adsorption of resveratrol, and also provided an efficient and simple approach for the selective purification of resveratrol from P. cuspidatum extracts for food/nutraceutical applications.

Surface molecularly imprinted polymer/covalent organic framework/silica composite material with specific recognition ability and excellent chromatographic performance.

Facing with the difficulty of specific chromatographic separation of nucleoside drugs, this study prepared a surface molecularly imprinted polymer (SMIP) modified covalent organic framework (COF) coated silica stationary phase based on the specificity of molecular imprinting technology and the powerful chromatographic separation performance of COF. This novel SMIP-COF@SiO2 stationary phase can not only specifically identify template molecule and structural analogs, but can also be used to separate multiple types of analytes, such as B vitamins, sulfonamides, alkylbenzenes, phenyl ketones, polycyclic aromatic hydrocarbons and environmental endocrine disruptors, which satisfies the need for complex sample separation. Various retention mechanisms have been investigated and multiple interactions between the SMIP-COF@SiO2 stationary phase and the analytes are discovered. The chromatographic performance of SMIP-COF@SiO2 is far superior to that of the SMIP@SiO2 and COF@SiO2. Furthermore, the SMIP-COF@SiO2 stationary phase can be successfully used to analyze polycyclic aromatic hydrocarbons in the environmental water sample and detect whitening ingredient in skincare product, indicating its great potential for application in various fields.

Selective Adsorption of Quercetin by the Sol-Gel Surface Molecularly Imprinted Polymer.

Quercetin, as one of the most biologically active natural flavonoids, is widely found in various vegetables, fruits and Chinese herbs. In this work, molecularly imprinted polymer (MIP) was synthesized through surface molecular imprinting technology with sol-gel polymerization mechanism on SiO2 at room temperature using quercetin as the template, SiO2 as the supporter, 3-aminopropyltriethoxysilane (APTES) as the functional monomer, and tetraethoxysilane (TEOS) as the cross-linker. The prepared MIP was characterized via scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and nitrogen adsorption measurements to validate its surface morphology, structure and functionality. SEM images revealed that the morphology of MIP was rough and spherical with the particle size of 260 nm larger than that of the support SiO2. In the FTIR spectra of MIP, the band around 1499 cm-1 and 2932 cm-1 were assigned to N-H and C-H groups, respectively. The results indicated that the imprinted polymer layers were grafted on the surface of SiO2 and the MIP had been successfully prepared. Since the specific surface area and pore volume of MIP were markedly higher than those of NIP and SiO2 and were 52.10 m2 g-1 and 0.150 cm3 g-1, respectively, it was evident that the imprinting process created corresponding imprinted cavities and porosity. The MIP for adsorbing quercetin was evaluated by static adsorption experiment. The results indicated that the adsorption equilibrium could be reached within 90 min and the maximum adsorption capacity was as high as 35.70 mg/g. The mechanism for adsorption kinetics and isotherm of MIP for quercetin was proved to conform the pseudo-second-order kinetics model (R2 = 0.9930) and the Freundlich isotherm model (R2 = 0.9999), respectively, revealing that chemical adsorption and heterogeneous surface with multilayer adsorption dominated. In contrast to non-imprinted polymer (NIP), the MIP demonstrated high selectivity and specific recognition towards quercetin whose selectivity coefficients for quercetin relative to biochanin A were 1.61. Furthermore, the adsorption capacity of MIP can be maintaining above 90% after five regeneration cycles, indicating brilliant reusability and potential application for selective adsorption of quercetin.

Molecularly imprinted polymers-isolated AuNP-enhanced CdTe QD fluorescence sensor for selective and sensitive oxytetracycline detection in real water samples.

A molecularly imprinted polymers (MIPs)-isolated AuNP-enhanced fluorescence sensor, AuNP@MIPs-CdTe QDs, was developed for highly sensitive and selective detection of oxytetracycline (OTC) in aqueous medium. The developed sensor combined the advantages of strong fluorescence signal of metal-enhanced fluorescence (MEF), high selectivity of MIPs, and stability of CdTe QDs. The MIPs shell with specific recognition served as an isolation layer to adjust the distance between AuNP and CdTe QDs to optimize the MEF system. The sensor demonstrated the detection limit as low as 5.22 nM (2.40 µg/L) for a concentration range of 0.1-3.0 µM OTC and good recovery rates of 96.0-103.0% in real water samples. In addition, high specificity recognition for OTC over its analogs was achieved with an imprinting factor of 6.10. Molecular dynamics (MD) simulation was utilized to simulate the polymerization process of MIPs and revealed H-bond formation as the mainly binding sites of APTES and OTC, and finite-difference time-domain (FDTD) analysis was employed to obtain the distribution of electromagnetic field (EM) for AuNP@MIPs-CdTe QDs. The experimental results combined with theoretical analyses not only provided a novel MIP-isolated MEF sensor with excellent detection performance for OTC but also established a theoretical basis for the development of a new generation of sensors.

Surface molecularly imprinted-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for highly selective and sensitive direct analysis of paraquat in complicated samples.

Herein, a novel surface molecularly imprinted-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (SMI-MALDI-TOF MS) method for direct target paraquat (PQ) analysis in complicated samples is reported. Notably, a captured analyte-imprinted material can be directly detected via MALDI-TOF MS by using imprinted material as nanomatrix. Using this strategy, the molecular specific affinity performance of surface molecularly imprinted polymers (SMIPs) and the high-sensitivity detection capability of MALDI-TOF MS was integrated. The introduction of SMI endowed the nanomatrix with the capacity for rebinding the target analyte and ensuring specificity, prevented the interfering organic matrix, and enhanced the analyzing sensitivity. By using paraquat (PQ) as a template, dopamine as a monomer, and covalent organic frameworks with a carboxyl group (C-COFs) as a substrate, polydopamine (PDA) was decorated on C-COFs via a simple self-assembly procedure to generate an analyte-based surface molecularly imprinted polymer (C-COF@PDA-SMIP), which served the dual function of SMIP capturing the target analytes and high-efficiency ionization. Thus, a reliable MALDI-TOF MS detection PQ with high selectivity and sensitivity as well as an interference-free background was achieved. The synthesis and enrichment conditions of C-COF@PDA-SMIPs were optimized, and its structure and property were characterized. Under optimal experimental conditions, the proposed method achieved highly selective and ultrasensitive detection of PQ from 5 to 500 pg mL-1, and the limit of detection was as low as 0.8 pg mL-1, which is at least three orders of magnitude lower than that achieved without enrichment. In addition, the specificity of the proposed method was superior to that of C-COFs and nonimprinted polymers. Moreover, this method exhibited reproducibility, stability, and high salt tolerance. Lastly, the practical applicability of the method was successfully verified by analyzing complicated samples, such as grass and orange.

A review: Development and application of surface molecularly imprinted polymers toward amino acids, peptides, and proteins.

Molecularly imprinted polymers (MIPs) have received wide interests in the bioanalysis field as "artificial antibodies". They can mimic biological receptors by selectively recognizing and adsorbing target molecules owing to their specific affinity to the targets. Traditional MIPs obtained by bulk imprinting have some defects, including low adsorption capacity, poor site accessibility, restricted mass transfer, and irregular morphology, which limit their development. Surface molecularly imprinted polymers (SMIPs) show the features of large surface area, allow fast mass transfer, and have high adsorption capacity and efficiency. They have been intensively used in the research of amino acids, peptides, and proteins due to these advantages. In this review, we systematically summarize the preparation of SMIPs including components and polymerization strategies, and their applications focusing on amino acids, peptides, and proteins are discussed in detail. Finally, future trends and challenges for the design and development of SMIPs are described.

A SiO2@MIP electrochemical sensor based on MWCNTs and AuNPs for highly sensitive and selective recognition and detection of dibutyl phthalate.

A molecularly imprinted sensor for highly sensitive and selective determination of dibutyl phthalate (DBP) was fabricated by combining multi-walled carbon nanotubes (MWCNTs) and Au nanoparticles (AuNPs) with surface molecularly imprinted polymer (SMIPs). The MWCNTs and AuNPs were designed to modify the electrode surface to accelerate the electron transfer rate and enhance the chemical stability. SMIPs were synthesized using SiO2 microspheres as carriers. By loading SMIPs capable of identifying DBP on the surface of modified electrodes of MWCNTs and AuNPs, an electrochemical sensor for detecting DBP was successfully constructed. After optimizing the experimental conditions, the modified electrode SiO2-COOH@MIP/AuNPs/MWCNTs/GCE can recognize DBP in the range of 10-7g L-1 to 10-2g L-1, and the detection limit achieved to 5.09 × 10-9 g L-1 (S/N = 3). The results demonstrate that the proposed MIP electrochemical sensor may be a promising candidate electrochemical strategy for detecting DBP in complex samples.

Magnetic Surface Molecularly Imprinted Polymer for Selective Adsorption of 4-Hydroxycoumarin.

4-hydroxyl coumarin (HC), an important intermediate during the synthesis procedure of rodenticide and anti-cardiovascular drug, shows highly medicinal value and economic value. To achieve the efficient adsorption of HC from natural biological samples, a novel magnetic surface molecularly imprinted polymer (HC/SMIPs) was constructed by employing methacrylic acid (MAA) as functional monomer, organic silane modified magnetic particles as matrix carrier and HC as template molecule. Due to the numerous specific imprinted cavities on the HC/SMIPs, the maximum adsorption capacity of HC/SMIPs for 4-hydroxycoumarin could reach to 22.78 mg g-1 within 20 min. In addition, HC/SMIPs exhibited highly selective adsorption for 4-hydroxycoumarin compared with other active drug molecules (osthole and rutin) and showed excellent regeneration performance. After 8 cycles of adsorption-desorption tests, the adsorption capacity of HC/SMIPs just slightly decreased by 6.64%. The efficient selective removal and easy recycle of 4-hydroxycoumarin from biological samples by HC/SMIPs made a highly promising to advance the application of imprinting polymers in complex practical environments.

A novel surface imprinted resin for the selective removal of metal-complexed dyes from aqueous solution in batch experiments: ACB GGN as a representative contaminant.

Metal-complexed dyes are harmful to the environment and human health because they contain heavy metals and complex organic ligands. It is difficult to separate and recover these dyes from wastewater owing to their complex components and poor selectivity of common adsorbents. In this study, a novel surface molecularly imprinted polymer (SMIP) was prepared using 4-vinyl pyridine as the functional monomer and polystyrene resin as the carrier. SMIP showed better adsorption performance than non-imprinted polymer (SNIP) in the whole pH range with the best adsorption capacity at pH 1.5. The correlation coefficients (R2) fitted by Langmuir and Temkin models were greater than 0.97, and the adsorption was a spontaneous exothermic process. The pseudo-second-order and Elovich models fitted the adsorption kinetic curves well. The adsorption capacity of SMIP was approximately 20% higher than that of SNIP in the salt concentration ranging from 2 to 80 mg/L. In selective adsorption experiments, the relative selectivity coefficients (I) of SMIP for competitors were all greater than 2.41, and the Cr (Ⅲ) components of ACB GGN played a more important role in the recognition performance of SMIP than the sulfonic groups. Adsorption mechanism tests revealed that although the adsorption of ACB GGN by SMIP mainly relied on electrostatic attraction, hydrophobic interactions, π-π conjugation, and Cr (Ⅲ) coordination were also involved. These results show that SMIP has excellent selective adsorption properties for ACB GGN and a promising application potential in the treatment of metal-complexed dye wastewater.

Photoresponsive Surface Molecularly Imprinted Polymers for the Detection of Profenofos in Tomato and Mangosteen.

As a moderately toxic organophosphorus pesticide, profenofos (PFF) is widely used in agricultural practice, resulting in the accumulation of a high amount of PFF in agricultural products and the environment. This will inevitably damage our health. Therefore, it is important to establish a convenient and sensitive method for the detection of PFF. This paper reports a photoresponsive surface-imprinted polymer based on poly(styrene-co-methyl acrylic acid) (PS-co-PMAA@PSMIPs) for the detection of PFF by using carboxyl-capped polystyrene microspheres (PS-co-PMAA), PFF, 4-((4-(methacryloyloxy)phenyl)diazenyl) benzoic acid, and triethanolamine trimethacrylate as the substrate, template, functional monomer, and cross-linker, respectively. PS-co-PMAA@PSMIP shows good photoresponsive properties in DMSO/H2O (3:1, v/v). Its photoisomerization rate constant exhibits a good linear relationship with PFF concentration in the range of 0~15 µmol/L. PS-co-PMAA@PSMIP was applied for the determination of PFF in spiked tomato and mangosteen with good recoveries ranging in 94.4-102.4%.

Reasonable design and sifting of microporous carbon nanosphere-based surface molecularly imprinted polymer for selective removal of phenol from wastewater.

Highly selective surface molecularly imprinted polymer (SMIP) was prepared on glucose-derived microporous carbon nanospheres (GMCNs) by surface molecular imprinting technology for the removal of phenol from wastewater. GMCNs with rich pore structure and surface oxygenic functional groups were adopted as support materials, on which the active layers were constructed by grafting silane coupling agent 3-(methacryloyloxy) propyltrimethoxysilane. Then with phenol as template molecule, different types and amounts of functional monomer (including methacrylic acid and 4-vinylpyridine (4-VP)) were screened for optimizing imprinting conditions suitable for phenol adsorption, and a series of SMIP was obtained through crosslinking polymerization. The adsorption behaviors of SMIP were evaluated by UV spectrophotometry. The results show that, when 4-VP is used as functional monomer, the resultant 4-VP/SMIP exhibites an excellent adsorption capacity of 85.72 mg g-1. The relative selectivity factor for phenol against hydroquinone, p-nitrophenol and p-tert-butylphenol is 8.38, 7.96 and 6.67, respectively, indicating outstanding adsorption capacity and selectivity of 4-VP/SMIP. The pseudo-second-order model and Langmuir‒Freundlich model fit better than other models for the adsorption of phenol. 4-VP/SMIP is promising for selective removal and enrichment recovery towards phenol in wastewater.

Surface molecularly imprinted polymer based on core-shell Fe3O4@MIL-101(Cr) for selective extraction of phenytoin sodium in plasma.

Core-shell magnetic Fe3O4@MIL-101(Cr) nanoparticles were synthesized via layer-by-layer self-assembly method. Using Fe3O4@MIL-101(Cr) as support, Fe3O4@MIL-101(Cr)@MIP was prepared with phenytoin as template, acrylamide as functional monomer, ethylene glycol dimethacrylate as cross-linker, methanol and acetonitrile as porogen, azoisobutyronitrile as initiator. The materials were characterized by a serious of characterization experiments. The prepared Fe3O4@MIL-101(Cr)@MIP was demonstrated to possess good separability, large adsorption capability, excellent adsorption selectivity, good durability and reusability via adsorption experiments. Subsequently, a magnetic solid phase extraction method (MSPE) based on Fe3O4@MIL-101(Cr)@MIP combined with high performance liquid chromatography-ultraviolet detector (HPLC-UV) was established for the determination of phenytoin sodium in plasma samples. Experimental parameters including pH, the amount of adsorbent, extraction time, elution conditions, the concentration of NaCl were investigated to optimize extraction process. The method was validated. The linearity was observed in the range of 0.05-40 µg mL-1 with a lower limit of quantification of 0.05 µg mL-1. The calibration equations were y = 0.2514x + 0.0319 (r2 = 0.9938), y = 0.2888x + 0.0472 (r2 = 0.9943), y = 0.2565x + 0.0418 (r2 = 0.9976), respectively. The recoveries ranged from 89.2 to 94.3%, intra- and inter-day precision (RSDs) ranged from 2.1 to 9.7% and 2.9-9.2%, respectively. The established MSPE-HPLC-UV method was time-saving, sensitive, accurate, environmental friendly, and drastically reduced the complex matrix interferences. The established method was successfully applied for phenytoin sodium determination in real plasma samples, providing new directions for therapeutic drug monitoring.

Highly Sensitive Determination of 2,4,6-Trichlorophenol by Using a Novel SiO2@MIPIL Fluorescence Sensor with a Double Recognition Functional Monomer.

A novel SiO2@ MIPIL fluorescence sensor for the highly sensitive detection of 2,4,6-trichlorophenol was prepared by using surface molecularly imprinting technology with SiO2 microspheres as carriers and 3,3'-(anthracene-9,10-diylbis(methylene))bis(1-vinyl-1H-imidazole-3-ium) chloride as a double recognition fluorescence functional monomer. The prepared molecularly imprinted polymer (SiO2@MIPIL) was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, laser confocal microscopy, and nuclear magnetic resonance. Compared with the polymer obtained via bulk polymerization (MIPIL), the surface molecularly imprinted polymer (SiO2@MIPIL) has a better linear range (0.1-50 nM), lower detection limit (89 pM), and shorter detection time (approximately 1.5 min). The fluorescence sensor also shows good specificity, high sensitivity, good stability, and reusability. Satisfactory results were obtained when using this sensor in industrial wastewater and spiked environmental water.

An NIR-light-responsive surface molecularly imprinted polymer for photoregulated drug release in aqueous solution through porcine tissue.

The application of photoresponsive surface molecularly imprinted polymers based on azobenzene is limited by the UV light source required and their poor water solubility. Reducing the phototoxicity and solvent toxicity of the polymers therefore presents a challenge. In this work, an NIR-light-responsive surface molecularly imprinted polymer was fabricated by atom transfer radical polymerization using up-conversion nanoparticles as the core, a hydrophilic green-light-responsive azobenzene derivative as the functional monomer, and a drug as the template. The up-conversion nanoparticles core emitted green fluorescence in the range of 520-550 nm upon NIR irradiation (980 nm, 5 W cm-2), which was absorbed by the azobenzene containing molecularly imprinted polymers layer on the up-conversion nanoparticles surface. This caused the azobenzene chromophores to undergo trans→cis isomerization in phosphate buffered solution (pH = 7.4), thus resulting in NIR-light-induced drug release. The up-conversion fluorescence spectra were used to study the interaction mechanism between the azobenzene monomer and NIR light. Compared with structural analogues of the template (antifebrin and phenacetin), the NIR-light-responsive surface molecularly imprinted polymer showed excellent specificity of recognition for the template drug (paracetamol). The maximum adsorption capacity of the NIR-light-responsive surface molecularly imprinted polymer for loading of paracetamol was 16.80 µmol g-1. The NIR-light-responsive surface molecularly imprinted polymer was applied for NIR-light-induced paracetamol release in phosphate buffered solution (pH = 7.4) through porcine tissue. This work demonstrates the potential of drug delivery systems based on molecularly imprinted polymers for application in deep tissue delivery.

Interference-free and high precision biosensor based on surface enhanced Raman spectroscopy integrated with surface molecularly imprinted polymer technology for tumor biomarker detection in human blood.

The reliable quantitative analysis of tumor biomarkers in circulating blood is crucial for cancer early screening, therapy monitoring and prognostic prediction. Herein, a novel biosensor combing surface-enhanced Raman spectroscopy (SERS) and surface molecularly imprinted polymer (SMIP) technology was developed for quantitative detection of carcinoembryonic antigen (CEA) that is closely related to several common cancers. Owing to the use of SMIP, recognition sites with high affinity to the target of interest can be well imprinted on the surface of SERS substrate, leading to a more stable and specific capture ability. In addition, two layers of core-shell nanoparticles were integrated to this SERS substrate to form highly efficient electromagnetic enhancement for SERS measurement via the generation of lots of "hot spot". Besides, a unique Raman reporter (CC) with silent Raman signals at 2024 cm-1 was capsulated in the nanoparticles to avoid the optical noises originating from endogenous molecules at fingerprint region (300-1800 cm-1). Meanwhile, we employed an internal standard molecular (CN) to real time correct the fluctuating signals of Raman reporter when performing the quantitative analysis. Due to these features, a limit of detection (LOD) of 0.064 pg mL-1 with the detection range of 0.1 pg mL-1 - 10 µg mL-1 can be achieved by this assay. Excitingly, this technology even showed wonderful performances for CEA detection in real blood from cancer patients, demonstrating great potential for biomarker-based cancer screening.

[Synthesis and application of a surface molecularly imprinted adsorbent for di(2-ethylhexyl)phthalate base on graphite oxide].

A molecularly imprinted polymer (MIP) base on the surface of graphite oxide (GO) has been developed for the selective recognition of di(2-ethylhexyl)phthalate (DEHP), and applied for the extraction of DEHP in a milk bag sample, with detection by high-performance liquid chromatography. The surface-molecularly imprinted material was prepared by precipitation polymerization in N,N-dimethylformamide (DMF) solvent, using GO as the supporting material, DEHP as the template molecule, and methacrylic acid (MAA) as the functional monomer; the synthesis conditions were also optimized. The obtained GO-MAA-MIP was characterized by Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). The adsorption properties of the product were evaluated by adsorption experiments, including adsorption isotherms, kinetics, selectivity, saturated adsorption capacity, adsorption equilibrium time, and reusability. Under optimized conditions, DEHP was effectively extracted in the real sample (milk bag) and detected by HPLC. Linearity was obtained with a correlation coefficient (R2) of 0.9979 in a linear range of 0.5-50 mg/L. The limits of detection and quantitation were 0.03 mg/L and 0.1 mg/L, respectively. The average recoveries of the spiked samples at three concentration levels of DEHP ranged from 81.6% to 92.4% with relative standard deviations (RSDs) less than 7%. The results indicated that the proposed GO-MAA-MIP-SPE (solid phase extraction) protocol with HPLC-UV detection could be applied for the selective analysis of DEHP in real samples.

[Preparation and application of tilmicosin-templated magnetic surface molecularly imprinted polymer].

A novel magnetic surface molecularly imprinted adsorbent is described. Fe3O4@SiO2, tilmicosin, and methacrylic acid were chosen as the support substrate, template molecule, and functional monomer, respectively. 3-Methacryloxypropyltrimethoxysilane was chemically bonded onto the surface of Fe3O4@SiO2 via a silanization reaction and used as the crosslinking agent in the subsequent reaction. The obtained magnetic surface molecularly imprinted polymer (MS-MIP) showed high selectivity and high enrichment capacity towards macrolide antibiotics (MACs), as indicated by the 212-, 275-, 675-, and 293-fold enrichment factors for spiramycin, josamycin, tilmicosin, and tylosin tartrate, separately. Because of the marked cavities onto the surface of the MS-MIP, the time required to reach adsorption equilibrium (30 min) was shorter than that for traditional MIP sorbents. Moreover, the adsorbent could be reused at least 6 times. Finally, the MS-MIP was used in combination with high performance liquid chromatography-ultraviolet detection (HPLC-UV) for the extraction and enrichment of four MACs in milk powder samples. The limits of detection (LODs) and limits of quantitation (LOQs) for the four MACs were in the range of 0.58-1.36 µg/kg and 1.92-4.55 µg/kg, respectively. The interday (n=5) and intraday (n=3) recoveries were in the range of 83.2%-123.0% at three spiked levels of 80, 200, and 500 µg/kg, under all the experimental conditions employed, and the relative standard deviations were less than 12.2%.

Visible-Light-Responsive Surface Molecularly Imprinted Polymer for Acyclovir through Chicken Skin Tissue.

The phototoxicity of UV light limits the application of conventional azobenzene-based photoresponsive molecularly imprinted polymers in the biomedical field. This paper reports a tetra-ortho-methoxy-substituted azobenzene, N-(4-((4-amino-2,6-dimethoxyphenyl)diazenyl)-3,5-dimethoxyphenyl)methacrylamide (ADDDM), whose photoswitching is induced by all visible-light irradiation (440 nm for trans form to cis form and 630 nm for cis form to trans form) in N,N-dimethylformamide and tetrahydrofuran (1:9, v/v). Using ADDDM as the monomer, a visible-light-responsive surface molecularly imprinted polymer (VSMIP) on silica microspheres was fabricated for acyclovir (ACV). VSMIP showed a higher drug loading capacity, better specificity, faster drug release rate, and faster photoisomerization rate constant to ACV than the corresponding visible-light-responsive surface molecularly nonimprinted polymer (VSNIP). The selectivity of VSMIP to ACV and competing materials (ganciclovir and triacetylganciclovir) was examined by ultraviolet-visible spectroscopy, and the VSMIP showed excellent specificity of recognition toward ACV. The VSMIP can realize a visible-light-triggered (440/630 nm) release and uptake of ACV through chicken skin tissue (1 mm in thickness).