A magnetic mesoporous carbon material (Fe3O4@C) was fabricated by carbonizing polystyrene grafted polydopamine-coated magnetic nanoparticles. The chemical composition, morphology and magnetism of the mesoporous carbon materials were characterized. The as-prepared magnetic mesoporous carbon was employed for enrichment of chlorophenols from water samples coupled with high-performance liquid chromatography with UV detection (HPLC-UV). Various parameters affecting the enrichment were investigated. A good linearity was obtained in the range of 10–200 ng mL−1 for 2-CP, 4-CP and 2,4-DCP, and 5–200 ng mL−1 for 2,4,6-TCP. The recoveries of CPs were in the range of 84.2–120% with intra- and inter-relative standard deviations (RSD) lower than 11.0%. The proposed method is fast, convenient and environmentally friendly. The results revealed the suitability of Fe3O4@C nanoparticles as adsorbents for enrichment of CPs from environmental water samples.

•A sandwich boronate affinity sorbent assay for glucose was established.•The method is selective and ultrasensitive for glucose detection.•A boronic acid terminated fluorescent polymer was used for signal amplification.•The developed method was applied to glucose detection of in human serum.Glucose monitoring is very important in clinical diagnosis, control and therapy of diabetes. Fluorescent methods based on boronate affinity recognition have attracted much attention in recent years. However, severe interferences from endogenous fluorophores or quenchers in samples are big concerns. In this work, a boronic acid terminated fluorescent polymer with multiple repeated fluorogens was synthesized by copolymerization of a fluorescent monomer [9-anthracenemethyl acrylate (9-AnMA)] and methyl methacrylate (MMA) via atom transfer radical polymerization (ATRP), and a sandwich boronate affinity sorbent assay (SBASA) for selective and ultrasensitive detection of glucose was developed for the first time based on the distinguished feature of glucose which can form a bidentate glucose–boronic complex, using the fluorescent polymer for signal amplification. The proposed method could avoid the effects from typical interfering substances. Compared with previously reported methods, the SBASA has higher selectivity, wider linear range (0.003 to 3.0 mM) and higher sensitivity (a detection limit of 0.8 μM). Moreover, the developed method was successfully applied to the detection of glucose in human serum samples. The simple, rapid, convenient, and reliable SBASA provided a new concept and an attractive idea for glucose monitoring.Download high-res image (126KB)Download full-size image

•High capacity boronate affinity adsorbents were prepared via SI-RAFT.•The adsorbents possess high adsorption capacity and good selectivity to ribonucleosides.•The adsorbents exhibit faster adsorption and desorption speed towards ribonucleosides.•The adsorbents were used to selectively enrich ribonuclosides from calf serum.Boronate affinity adsorption is uniquely selective for cis-diol-containing molecules. The preparation and application of boronate affinity materials has attracted much attention in recent years. In this work, a high-capacity boronate affinity adsorbent was prepared by surface-initiated reversible addition–fragmentation chain transfer polymerization (SI-RAFT). Commercial aminated poly(glycidyl methacrylate) (PGMA) microspheres were modified with the chain transfer agent (CTA) S-1-dodecyl-S-(α,α-dimethyl-α-acetic acid)trithiocarbonate (DDATC). Boronate-affinity adsorbents were then prepared via SI-RAFT polymerization employing 3-acrylamidophenylboronic acid (AAPBA) as the monomer. The Fourier transform infrared spectroscopy (FT-IR), nitrogen adsorption and desorption measurements have proven the successful grafting of AAPBA on PGMA microspheres surface. The boronate affinity adsorbents thus prepared possess much higher adsorption capacity (99.2 µmol/g of adenosine) and both faster adsorption and desorption speed towards ribonucleosides, the adsorption and desorption could be completed in 2 min. The high selectivity of the adsorbents to ribonucleosides was verified in the presence of a large excess of deoxynucleosides. The boronate affinity adsorbents were then employed for sample pretreatment before HPLC analysis of ribonucleosides in serum. The ribonucleosides were effectively enriched by boronate affinity dispersive solid-phase extraction (BA-DSPE), with high mass recoveries and good precision. The simultaneous determination of uridine and guanosine in calf serum was achieved by utilizing the standard addition method, their contents were determined to be 170 ± 11.6 ng/mL and 39.6 ± 4.4 ng/mL respectively. The results proved that the prepared boronate affinity materials could be applied for sample pretreatment of cis-diol containing molecules in biological samples.

In this study, a weak cation-exchange (WCX) membrane was prepared via a “post-polymerization modification” method, which involved the surface-initiated atom transfer radical polymerization of glycidyl methacrylate (GMA) and subsequent two-step derivation. By varying the graft time of poly-GMA, a series of WCX membranes with different densities of carboxyl groups were fabricated. For the membrane with a graft time of 12 h, a high adsorption capacity of 125.0 mg mL−1 was obtained by using lysozme (Lys) as a model protein, which is higher than that reported. The new parameters, the utilization percentage of carboxyl (UP) and the stoichiometric displacement parameter (Z) were introduced to theoretically investigate how the ligand density affects the adsorption behavior of Lys for the first time. The UP revealed an “increase first and then decrease” trend with the prolonging of graft time, which may result from the mutual effect of the flexibility of the polymer chain, the steric hindrance and the “adsorption-caused hindrance” effect. Remarkably, the Z value was found to increase with the prolonging of graft time, suggesting that more effective binding sites were interacting with a protein molecule when the density of carboxyl was increased. Finally, the WCX membranes were applied to purify Lys from egg white with a high recovery of 95.7%, which depends significantly on the adsorption capacity of the membranes.

Environmental protection has become a very important issue. The transformation of solid waste into profitable products to remove hazardous chemicals from environmental samples has attracted much attention. In this study, inactivated immobilized enzymes were reutilized by converting into an adsorbent for the first time, and poly(sodium 4-styrene sulfonate) (poly(NASS)) was grafted from the surface of the particles using surface-initiated atom transfer radical polymerization (SI-ATRP) to produce a strong cation exchanger. X-ray photoelectron spectroscopy (XPS) confirmed the successful grafting of poly(NASS). The cation exchanger exhibited very good performance for the adsorption of methylene blue (MB) with a high capacity (409.8 mg g−1) and fast speed (equilibrium achieved within 1 min), the removal ratio was more than 96.4–99.2% when the MB concentration ranged from 10 to 800 mg L−1, and the removal efficiency of the cation exchanger for MB was 397.1 mg (g−1 min−1), these properties are much better than those previously reported materials. The cation exchanger can be used for five times with removal ratio higher than 80%. Additionally, the adsorption exhibited no significant pH and temperature dependence, and more than 80% capacity was maintained at high concentrations of sodium chloride up to 0.4 mol L−1, therefore the exchanger is very favorable for removal of MB from wastewater with different pH values and salt concentrations, and can be used in a wide temperature range.

•Cu(II) immobilized Fe3O4 was used for enrichment of biological monoamine.•Monoamine neurotransmitters (MNTs) were selectively enriched in acidic solution.•The acidic enrichment condition improved the recovery of MNTs.In this paper, iminodiacetic acid-Cu(II) functionalized Fe3O4@SiO2 magnetic nanoparticles were prepared and used as new adsorbents for magnetic solid phase extraction (MSPE) of six monoamine neurotransmitters (MNTs) from rabbit plasma. The selective enrichment of MNTs at pH 5.0 was motivated by the specific coordination interaction between amino groups of MNTs and the immobilized Cu(II). The employed weak acidic extraction condition avoided the oxidation of MNTs, and thus facilitated operation and ensured higher recoveries. Under optimal conditions, the recoveries of six MNTs from rabbit plasma were in the range of 83.9–109.4%, with RSD of 2.0–10.0%. When coupled the Cu(II) immobilized MSPE with high-performance liquid chromatography-fluorescence detection, the method exhibited relatively lower detection limits than the previously reported methods, and the method was successfully used to determine the endogenous MNTs in rabbit plasma. The proposed method has potential application for the determination of MNTs in biological samples. Also, the utilization of coordination interaction to improve the selectivity might open another way to selectively enrich small alkaloids from complex samples.

•A novel method for preparation of reversed phase restricted access material (RAM).•The preparation method is simple and versatile.•The RAM has very good ability to retain small molecules and to exclude proteins.•RAM-SPE–HPLC method for detection of phthalate esters in milk was established.Restricted-access materials (RAMs) have been broadly used for sample pretreatment in the chromatographic analysis of biological samples. In the present work, a novel internal surface reversed-phase (ISRP) RAM was prepared via surface-initiated atom transfer radical polymerization (SI-ATRP). Octadecyl and 4-(chloromethyl)phenyl were immobilized on silica using a one-pot synthesis approach to form a reversed-phase layer to retain small hydrophobic molecules, allowing the modified silica to serve as a macro-initiator. Then, poly(glycidyl methacrylate) (pGMA) was grafted onto the surface via SI-ATRP, and the epoxy groups were further hydrolyzed to form an external hydrophilic layer. The properties of this ISRP-RAM for the retention of small molecules and the exclusion of proteins were evaluated using solid-phase extraction (SPE). The removal efficiencies of bovine serum albumin (BSA) and lysozyme were 94.9% and 93.5%, respectively. The recoveries of five drugs, puerarin, p-hydroxybenzaldehyde, loratadine, nifedipine and diazepam, were 93.2–116%. Furthermore, the ISRP-RAM was employed for the SPE of five phthalate esters (PAEs) from bovine milk prior to high-performance liquid chromatography (HPLC) analysis. The results indicate that the prepared ISRP-RAM is qualified for practical bioanalysis.

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is a very efficient therapeutic protein drug which has been widely used in human clinics to treat cancer patients suffering from chemotherapy-induced neutropenia. In this study, rhG-CSF was solubilized from inclusion bodies by using a high-pH solution containing low concentration of urea. It was found that solubilization of the rhG-CSF inclusion bodies greatly depended on the buffer pH employed; alkalic pH significantly favored the solubilization. In addition, when small amount of urea was added to the solution at high pH, the solubilization was further enhanced. After solubilization, the rhG-CSF was renatured with simultaneous purification by using weak anion exchange, strong anion exchange, and hydrophobic interaction chromatography, separately. The results indicated that the rhG-CSF solubilized by the high-pH solution containing low concentration of urea had much higher mass recovery than the one solubilized by 8 M urea when using anyone of the three refolding methods employed in this work. In the case of weak anion exchange chromatography, the high pH solubilized rhG-CSF could get a mass recovery of 73%. The strategy of combining solubilization of inclusion bodies at high pH with refolding of protein using liquid chromatography may become a routine method for protein production from inclusion bodies.

Recombinant human stem cell factor (rhSCF) was solubilized and renatured from inclusion bodies expressed in Escherichia coli. The effect of both pH and urea on the solubilization of rhSCF inclusion bodies was investigated; the results indicate that the solubilization of rhSCF inclusion bodies was significantly influenced by the pH of the solution employed, and low concentration of urea can drastically improve the solubilization of rhSCF when solubilized by high pH solution. The solubilized rhSCF can be easily refolded with simultaneous purification by ion exchange chromatography (IEC), with a specific activity of 7.8 × 105 IU·mg−1, a purity of 96.3%, and a mass recovery of 43.0%. The presented experimental results show that rhSCF solubilized by high pH solution containing low concentration of urea is easier to be renatured than that solubilized by high concentration of urea, and the IEC refolding method was more efficient than dilution refolding and dialysis refolding for rhSCF. It may have a great potential for large-scale production of rhSCF.