ZIF-based boronic acid modified molecular imprinted polymers in combination with silver nanoparticles/glutathione coated graphene oxide adsorbent for the selective enrichment of ellagic acid.

This study focuses on the extraction of ellagic acid (EA), a valued phenolic compound, from agricultural waste chestnut shell samples. A novel approach is introduced using a combination of boronic acid-modified molecularly imprinted polymer (ZIF@B@MIP) and a nanocomposite of graphene oxide-coated silver nanoparticles (GO@Ag@GSH) to enhance EA enrichment. ZIF@B@MIP precisely captured EA through boronate affinity-based molecular imprinting recognition. ZIF@B@MIP employs boronate affinity-based molecular imprinting recognition to precisely capture EA, while GO@Ag@GSH provides ample adsorption sites. The synergistic effect of ZIF@B@MIP and GO@Ag@GSH demonstrates excellent enrichment capability and selectivity for EA. High-performance liquid chromatography (HPLC) is employed for sensitive EA detection, achieving a maximum adsorption capacity of 46.25 mg g-1 and an imprinting factor of 3.01. The adsorption capacity to different structural analogue was investigated, and the selectivity coefficient was used to evaluate the selectivity, and its value was 1.16-3.01. The method successfully enriches EA in chestnut shell samples with a recovery rate of 95.6 %-110.1 %. This research presents an innovative approach for effective phenolic components enrichment from natural resources for pharmaceutical and biochemical applications.

Construction of the molecularly imprinted adsorbent based on shaddock peel biochar sphere for highly sensitive detection of ribavirin in food and water resources.

Ribavirin (RBV) that is not metabolically released into the environment can contaminate the environment and even make organisms resistant to it. Therefore, it is of great significance to establish a simple and effective method for adsorbing RBV in the environment. In this study, a novel biochar-based boronate affinity molecularly imprinted polymers (C@H@B-MIPs) were synthesized. This is the first time that shaddock peel biochar sphere was used as a carrier for specific recognition of RBV. The polymerization conditions were optimized and the binding properties of RBV were studied. Benefiting from the synergistic effect of boronate affinity and surface imprinting, the C@H@B-MIPs showed rapid equilibrium kinetics of 15 min, high adsorption capacity of 18.30 mg g-1, and excellent reusability for RBV. The linear range was 0.05-100 mg L-1, and the detection limit was 0.023 mg L-1. This method was triumphant applied to the selective adsorption of RBV in food and water resources with recovery rates of 81.4-97.7%. This study provides a practical platform for the manufacture of efficient biomass-based adsorbents.

Metal oxide-based macroporous ordered double affinity molecularly imprinted polymer for specific separation and enrichment of glycoprotein from food samples: a co-modification of DMSA and boronate affinity.

Metal oxide-based macroporous ordered double affinity molecularly imprinted polymers (D-MIPs) were developed as solid phase extraction (SPE) adsorbents for the specific identification of ovalbumin (OVA) under physiological pH conditions prior to ultraviolet visible (UV-vis) spectrophotometric detection. Herein, macroporous alumina (MA) was used as a matrix; dimercaptosuccinic acid (DMSA) and 3-aminophenylboric acid (APBA) were employed as dual-functional monomers; APBA is a self-polymerizing monomer. The effects of synthesis conditions, SPE conditions as well as selectivity, reproducibility, and reusability were studied. The co-modification of DMSA and boronate affinity renders the adsorbent exhibiting a high adsorption capacity (114.4 mg g-1) and short equilibrium time (30 min). The surface imprinting technology causes the adsorbent to have high selectivity towards OVA. The OVA recovery range is 91.1-99.6%. This study provides a promising method for the enrichment of OVA and other cis-diol-containing analytes in complex biological samples. A novel metal oxide-based macroporous ordered nanoparticle with a combination of DMSA and boronate affinity was successfully prepared for specific separation and enrichment of glycoprotein from complex biological samples.

ZIF-based boronic acid functionalized metal-organic frameworks for the enrichment of cis-diol-containing luteolin from food samples prior to HPLC.

Zeolite imidazole framework-based boronic acid-functionalized metal-organic frameworks (ZIF-67@PDA@BA-Zr-MOFs) were developed as an adsorbent for solid phase extraction (SPE) of luteolin (LTL) from peanut shell samples. Herein, ZIF-67 as a support matrix, polydopamine (PDA) as a coating to introduce amino and hydroxyl groups on the matrix surface to fix metal-organic frameworks (MOFs), zirconium tetrachloride (ZrCl4) as a precursor, terephthalic acid (TPA), and 3-carboxyphenylboronic acid (3-CPBA) as the mutual organic building blocks, and 3-CPBA was also a boronate affinity functional monomer. The effects of synthesis conditions, SPE conditions, selectivity, competitivity, reproducibility, and reusability were evaluated in detail. Under the optimal conditions, the maximum adsorption capacity is 71.4 mg g-1. The utility of ZIF-67@PDA@BA-Zr-MOFs as an adsorbent for SPE of LTL is supported by the presence of the abundant pore structure, as well as the boronate affinity sites facilitated the rapid binding of the adsorbent to the template. The concentration of the extracted LTL was determined by the high-performance liquid chromatography-ultraviolet (HPLC-UV), with calibration plots being linear in the concentration range 0.05-100 mg L-1 and a limit of detection (LOD) of 0.035 mg L-1. The method was applied to determine the LTL in peanut shell samples and recovered the target analyte in the range 85.6% to 99.2% (the standard deviations are less than 3.3%, n = 3). In addition, we incorporated boronate affinity and MOFs material into an SPE system to provide a promising strategy to detect other cis-diol-containing analytes in the complex matrix.

Gallic acid-affinity molecularly imprinted polymer adsorbent for capture of cis-diol containing Luteolin prior to determination by high performance liquid chromatography.

A gallic acid-affinity molecularly imprinted polymer (G-MIP) was first used as an adsorbent for selective identification and capture of luteolin (LTL) in herbal medicine samples. The G-MIP was prepared by using LTL as the template, gallic acid (GA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent, and 2,2'-azobis(2-methylpropionitrie) (AIBN) as the initiator. The properties of G-MIP were characterized by FT-IR, transmission electron microscope, scanning electron microscope, dynamic light scattering, specific surface area, and X-ray photoelectron spectrum. The adsorption conditions were optimized, and the adsorption equilibrium model and adsorption kinetics model of the adsorbent were investigated under the best experimental conditions. The saturated adsorption capacity is 1.24 mg g-1, which is not only higher than the adsorption capacity of 4-carboxyphenylboronic acid-affinity MIP adsorbent but also superior to those of many reported adsorbents for enriching of LTL. The LTL was quantified by HPLC. The linear range is 0.05-100 mg L-1, the detection limit is 0.020 mg L-1. This method was successfully applied in the selective recognition of LTL in herbal medicines with recoveries of 93.9-114.2%, and the relative standards deviations (RSDs) are 0.4-5.6%. Thus, this work provides a potential possibility and practical platform for the determination of LTL in complex matrices.

Boronate-modified polyethyleneimine dendrimer as a solid-phase extraction adsorbent for the analysis of luteolin via HPLC.

Luteolin (LTL) is a flavonoid containing a cis-diol, which has significant anti-inflammatory, anti-allergic, anti-diabetic, anti-cancer and neuroprotective activities. In this work, a silver modified boric acid affinity polyvinyl imine (PEI) dendritic adsorbent (PPEI-Ag@CPBA) was prepared on polystyrene (PS) for the rapid recognition and selective separation of LTL. A thin layer of polydopamine (PDA) was formed on the surface of the substrate by self-polymerization, and a PDA-coated PS material (PS@PDA) was obtained. PEI with sufficient active amino groups was grafted onto PS@PDA to obtain a PEI-modified material (PS@PDA@PEI), then AgNO3 was reduced with NaBH4, and PS@PDA@PEI was embedded on Ag. Finally, PPEI-Ag@CPBA was obtained through the condensation reaction of PEI with 4-carboxyphenyl boric acid (CPBA). The adsorption conditions were optimized, the optimal pH and the optimum amount of adsorbent were determined, and the maximum adsorption capacity was found to be 2.49 mg g-1. This method has been successfully applied to the selective identification of LTL in peanut shell samples, and provides a practical platform for the detection of LTL in complex substrates.

Using self-polymerization synthesis of boronate-affinity hollow stannic oxide based fragment template molecularly imprinted polymers for the selective recognition of polyphenols.

In this work, the boronate-affinity hollow stannic oxide based fragment template molecularly imprinted polymers (Bh@SnO2-FMIPs) were fabricated successfully. Polystyrene was used as sacrificial support, SnO2 was selected as inorganic matrix, surface imprinting using catechol as fragment template and 4-vinylphenylboronic acid as boronate-affinity functional monomer. A thin layer of poly 2-anilinoethanol (2-AE) was formed to coat the boronate-affinity hollow SnO2 surface through self-polymerization, it has strong hydrophilicity and limited residual boric acid content, avoiding non-specific binding. The hollow structure could bind to target molecules effectively and facilitate the removal of template molecules. The Bh@SnO2-FMIPs were used to extract three cis-diol polyphenols containing catechin, chlorogenic acid, and caffeic acid in tea and juice samples. Combination with seven characterizations of the material confirmed the successful preparation. Effecting the imprinting conditions and extraction efficiency parameters were optimized separately. Selective and competitive adsorption experiments indicated that the materials could specific recognition polyphenols. Using solid phase extraction and high performance liquid chromatography method, the detection limits were 0.005-0.046 µg mL-1 and the recoveries were between 82.3-104.3%. The improved adsorption performance may be assigned to the synergistic effects among boronate-affinity, hollow SnO2, and 2-AE self-polymerization. It may enhance binding cavities, hydrophilicity, biocompatibility of adsorbent material, and prevent the aggregation of Sn during the preparation processes.

Hollow dummy template imprinted boronate-modified polymers for extraction of norepinephrine, epinephrine and dopamine prior to quantitation by HPLC.

The authors describe boronate-modified hollow dummy template imprinted polymers (B-hDIPs) for selective and sensitive extraction of the catecholamines norepinephrine (NE), epinephrine (E), and dopamine (DA) from urine samples prior to their detection by HPLC with UV detector. The B-hDIPs were prepared by using (a) nano-TiO2 as the sacrificial support, (b) 3-carboxyphenylboronic acid (CPBA) as the boronate-affinity functional monomer, and (c) catechol which acts as dummy template. The nano-TiO2 can be etched off by using hydrofluoric acid to form the hollow imprint. The main advantages of using such hollow polymers arise from their controllable hole structure which favors template removal and fast mass transfer. The B-hDIPs material was characterized by FT-IR, transmission electron microscope, dynamic light scattering, X-ray photoelectron spectrum, and thermal gravimetric analysis. The effects of imprinting conditions, sample pH, sample flow rate, adsorbent amount, selectivity and competitive capacities were investigated. Under optimal conditions, the limits of detection for the catecholamines are in the range from 15 to 47 ng mL-1. The method was successfully applied to their determination of NE, E, and DA in spiked urine, with recoveries ranging from 63.4 to 106.2%. Graphical abstract Schematic presentation of boronate-modified hollow dummy template imprinted polymers as an adsorbent to extraction of the catecholamines (norepinephrine, epinephrine, and dopamine) from urine samples prior to their detection by HPLC-UV.

[γ-Al2O3-graphene oxide absorbent material for detection of nucleosides in urine].

γ-Al2O3 nanoparticle-bonded graphene oxide (γ-Al2O3-GO) was prepared for use as a solid phase extraction absorbent and for preconcentration of four nucleosides in human urine samples for investigation by high-performance liquid chromatography (HPLC). Transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FT-IR) were employed to characterize the absorbent. Several parameters (eluent species, absorbent amount, sample volume, and sample pH) were optimized, and the absorption efficiency was determined based on equilibrium absorbent amounts. Under optimal conditions, the γ-Al2O3-GO absorbent displayed enhanced absorbent ability for nucleosides. The calibration curve showed good linearities in the range of 0.10-10 mg/L for cytidine, inosine, and guanosine, and 0.05-10 mg/L for uridine; the correlation coefficient was observed to be in the range of 0.9967-0.9973. The limits of detection for the four nucleosides were in the range of 0.010-0.021 mg/L. Intra-day and inter-day relative standard deviations were 0.1%-0.8% and 1.0%-3.1%, respectively. The recoveries of the four nucleosides in urine samples ranged from 71.3% to 107.4%, and the relative standard deviations (n=3) were less than 4.8%. The results demonstrated that the proposed method is faster, more sensitive, and more efficient. Therefore, solid phase extraction (SPE)-based γ-Al2O3-GO can be considered more suitable for the determination and enrichment of nucleosides in urine samples.

Determination of sialic acid in serum samples by dispersive solid-phase extraction based on boronate-affinity magnetic hollow molecularly imprinted polymer sorbent.

Boronate-affinity magnetic hollow molecularly imprinted polymers (B-MhMIPs) were prepared with sialic acid (SA) as the template, 3-aminophenylboronic acid (APBA) as the functional monomer and glycidilmethacrylate (GMA) as the co-monomer to chemisorb Fe3O4 nanoparticles. Furthermore, the hollow structure made the nanoparticles have more binding sites at both internal and external surfaces, which can facilitate the removal of template molecules from polymers and enhance the adsorption abilities towards SA. After optimizing, the adsorption pH was controlled at 4.0, and this was different from most cis-diol-containing compounds. Under the optimal conditions, the limit of detection for SA was 0.025 µg mL-1 (n = 3). This method was applied to analyze serum samples with different spiked levels, and the recoveries of the SA were in the range of 70.9-106.2%. These results confirmed the superiority of the B-MhMIPs for selective and efficient enrichment of trace SA from complex matrices.