Dechun Liu

A highly-efficient imprinted magnetic nanoparticle for selective separation and detection of 17β-estradiol in milk.

In this work, we prepared molecularly imprinted polymers (MIPs) combining surface molecular imprinting technique and magnetic separation for separation and determination of 17β-estradiol (E2) from milk. During the synthesis process, the acryloyl chloride was specially used to graft double bonds on Fe3O4 nanoparticles and served as co-functional monomer cooperating with acrylamide. The morphology, structure property, and the best polymerization and adsorption conditions of the prepared magnetic nanoparticles were investigated in detail. The obtained nanomaterials displayed high adsorption capacity of 12.62mg/g, fast equilibrium time of 10min, and satisfactory selectivity for target molecule. Whats more, the MIPs was successfully applied as sorbents to specifically separate and enrich E2 from milk with a relatively high recovery (88.9-92.1%), demonstrating the potential application of the MIPs as solid phase extractant for rapid, highly-efficient, and cost-effective sample analysis.

Water-compatible magnetic imprinted nanoparticles served as solid-phase extraction sorbents for selective determination of trace 17beta-estradiol in environmental water samples by liquid chromatography

Endocrine disrupting compounds (EDCs) are a potential risk for wildlife and humans for their existence in water. The efficient extraction and clean-up steps are required before detection of low concentration levels of EDCs. In this work, a novel water-compatible magnetic molecularly imprinted nanoparticles is synthesized for the selective extraction of 17β-estradiol (E2) in environmental water samples. The preparation is carried out by introducing aldehyde groups to the surface of amino-functionalized magnetic nanoparticles through a simple one-step modification, followed by copolymerization of functional monomer gelatin and template E2 via surface imprinting technique. The gelatin with abundant active groups could not only act as functional monomer reacting with template, but also assemble covalently at the surface of magnetic nanoparticles. At the same time, gelatin would improve the water-compatibility of imprinted materials for attaining high extraction efficiency. To obtain high imprinting effect, the preparation conditions are optimized in detail using Central composite design-response surface methodology. The resultant polymers have uniform spherical shape with a shell thickness of about 8nm, stable crystalline form, and super-paramagnetic property. Meanwhile, the obtained polymers have high capacity of 12.87mgg(-1) and satisfactory selectivity to template molecule. To testify the feasibility of the magnetic imprinted polymers in sample pretreatment, a method for determination of trace E2 in environmental water samples was set up by combination of solid-phase extraction (SPE) using the prepared polymers as sorbents and HPLC for rapid isolation and determination of E2. The limit of detection of proposed method is 0.04ngmL(-1), the intra- and inter-day relative standard deviations (RSDs) are less than 4.6% and 5.7%, respectively. The recoveries of E2 from environmental water samples are in the range from 88.3% to 99.1% with the RSDs less than 7.2%.

Selective extraction and determination of chlorogenic acid in fruit juices using hydrophilic magnetic imprinted nanoparticles

In this paper, the novel hydrophilic magnetic molecularly imprinted nanoparticles were developed for selective separation and determination of chlorogenic acid in aqueous fruit juices. The polymers were prepared by using amino-functionalized magnetic nanoparticles as carriers, branched polyethyleneimine as functional monomer, and chlorogenic acid as template molecule. Branched polyethyleneimine with abundant active amino groups could react with template sufficiently, and its unique dendritic structure may amplify the number of the imprinted cavities. Meanwhile, it would improve the hydrophilicity of imprinted materials for attaining high extraction efficiency. The resulted polymers exhibit fast kinetics, high adsorption capacity, and favorable selectivity. In addition, the obtained nanoparticles were used as solid-phase extraction sorbents for selective isolation and determination of chlorogenic acid in peach, apple, and grape juices (0.92, 4.21, and 0.75 μg mL(-1), respectively).

Novel polydopamine imprinting layers coated magnetic carbon nanotubes for specific separation of lysozyme from egg white

Novel core-shell nanocomposites, consisting of magnetic carbon nanotubes (MCNTs) core surrounded by a thin polydopamine (PDA) imprinting shell for specific recognition of lysozyme (Lyz), were fabricated for the first time. The obtained products were characterized and the results showed that the PDA layer was successfully attached onto the surface of MCNTs and the corresponding thickness of imprinting layer was just about 10nm which could enable the template access the recognition cavities easily. The polymerization conditions and adsorption performance of the resultant nanomaterials were investigated in detail. The results indicated that the obtained imprinted polymers showed fast kinetic and high affinity towards Lyz and could be used to specifically separate Lyz from real egg white. In addition, the prepared materials had excellent stability and no obvious deterioration after five adsorption-regeneration cycles. Easy preparation, rapid separation, high binding capacity, and satisfactory selectivity for the template protein make this polymer attractive in biotechnology and biosensors.

A facile and general approach for preparation of glycoprotein-imprinted magnetic nanoparticles with synergistic selectivity

In light of the significance of glycoprotein biomarkers for early clinical diagnostics and treatments of diseases, it is essential to develop efficient and selective enrichment platforms for glycoproteins. In this study, we present a facile and general strategy to prepare the boronate affinity-based magnetic imprinted nanoparticles. Boronic acid ligands were first grafted on the directly aldehyde-functionalized magnetic nanoparticles through amidation reaction. Then, template glycoproteins were immobilized on the boronic acid-modified magnetic nanoparticles via boronate affinity binding. Subsequently, a thin layer of dopamine was formed to coat the surface of magnetic nanoparticles through self-polymerization. After the template glycoproteins were removed, the cavities that can specific bind the template glycoproteins were fabricated. Adopting horseradish peroxidase as model template, the effects of imprinting conditions as well as the properties and performance of the obtained products were investigated. The resultant imprinted materials exhibit highly favorable features, including uniform surface morphology with thin imprinted shell of about 8nm, super-paramagnetic property, fast kinetics of 40min, high adsorption capacity of 60.3mgg(-1), and satisfactory reusability for at least five cycles of adsorption-desorption without obvious deterioration. Meanwhile, the obtained magnetic imprinted nanoparticles could capture target glycoprotein from nonglycoproteins, but also from other glycoproteins because the synergistic selectivity of boronate affinity and imprinting effect. In addition, the facile preparation method shows feasibility in the imprinting of different glycoproteins.

One-step preparation of magnetic imprinted nanoparticles adopting dopamine-cupric ion as a co-monomer for the specific recognition of bovine hemoglobin.

A novel magnetic core-shell polydopamine-cupric ion complex imprinted polymer was prepared in one-step through surface imprinting technology, which could specifically recognize bovine hemoglobin from the real blood samples. The polymerization conditions and adsorption performance of the resultant nanomaterials were investigated in detail. The results showed that the cupric ion played an important role in the recognition of template proteins. The saturating adsorption capacity of this kind of imprinted polymers was 2.23 times greater than those of imprinted polymers without cupric ion. The imprinting factor of the imprinted materials was as high as 4.23 for the template molecule. The selective separation bovine hemoglobin from the real blood sample is successfully applied. In addition, the prepared materials had excellent stability and no obvious deterioration after five adsorption-regeneration cycles. Easy preparation, rapid separation, high binding capacity and satisfactory selectivity for the template protein make this polymer attractive in the separation of high-abundance proteins.

Novel magnetic multi-template molecularly imprinted polymers for specific separation and determination of three endocrine disrupting compounds simultaneously in environmental water samples

In order to improve the practical applied value of molecularly imprinted polymers, a novel concept of multiple templates was introduced to prepare an original type of magnetic molecularly imprinted polymers. The magnetic multi-template molecularly imprinted polymers were obtained by selecting silica-coated magnetic nanoparticles as supporters, three endocrine disrupting compounds (17β-estradiol (E2), estriol (E3), and diethylstilbestrol (DES)) as the multi-template, and two kinds of silane coupling agents (3-aminopropyltriethoxysilane (APTES) and phenyltrimethoxysilane (PTMOS)) as bifunctional monomers for simultaneously specific recognition of E2, E3, and DES. The as-synthesized polymers possessed homogeneous imprinting shells, stable crystalline phase, and super-paramagnetic properties. Meanwhile, the imprinted nanomaterials displayed not only extraordinarily fast kinetics, but also satisfactory adsorption capacity, as well as favorable selectivity. More importantly, the prepared polymers exhibited a similar recognition performance to a physical mixture of three single-template polymers, but the synthetic procedure of the former was simplified with significant reduction in both preparation time and solvent consumption. In addition, the imprinted nanoparticles were applied as a specific adsorbent coupled with HPLC-UV for rapid isolation and determination of E2, E3, and DES simultaneously. The limits of detection (LODs) of proposed method for three target estrogens of E2, E3, and DES were 0.27, 0.19, and 0.08 ng mL−1, respectively, which were lower than that obtained by some other sample pretreatment methods followed by HPLC-UV analysis. Furthermore, the developed method was successfully applied for detection of multiple aimed estrogens in environmental water samples with satisfactory recoveries in the range of 92.3–98.6%.

Preparation of biocompatible molecularly imprinted shell on superparamagnetic iron oxide nanoparticles for selective depletion of bovine hemoglobin in biological sample

Bovine hemoglobin (BHb), as one of the high-abundance proteins, could seriously mask and hamper the analysis of low-abundance proteins in serum. To selectively deplete BHb, we design a simple and effective strategy for preparation of biocompatible molecularly imprinted shell on superparamagnetic iron oxide nanoparticles through surface imprinting technique combined with template immobilization strategy. Firstly, template proteins are immobilized on the directly aldehyde-functionalized magnetic nanoparticles through imine bonds. Then, with gelatin as functional monomer, a polymeric network molded around the immobilized template proteins is obtained. Finally, the specific cavities for BHb are fabricated after removing the template proteins. The effects of imprinting conditions were investigated and the optimal imprinting conditions are found to be 40mg of BHb, 150mg of gelatin, and 8h of polymerization time. The resultant materials exhibit good dispersion, high crystallinity, and satisfactory superparamagnetic property with a high saturation magnetization (33.43emug(-1)). The adsorption experiments show that the imprinted nanomaterials have high adsorption capacity of 93.1mgg(-1), fast equilibrium time of 35min, and satisfactory selectivity for target protein. Meanwhile, the obtained polymers could be used without obvious deterioration after six adsorption-desorption cycles. In addition, the resultant polymers are successfully applied in the selective isolation BHb from bovine blood sample, which could provide an alternative solution for the preparatory work of proteomics.

Synthesis of magnetic dual‐template molecularly imprinted nanoparticles for the specific removal of two high‐abundance proteins simultaneously in blood plasma

Novel core-shell dual-template molecularly imprinted superparamagnetic nanoparticles were synthesized using bovine hemoglobin and bovine serum albumin as the templates for the efficient depletion of these two high-abundance proteins from blood plasma for the first time. The preparation process combined surface imprinting technique and a two-step immobilized template strategy. The obtained polymers were fully characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. The results showed that the as-synthesized nanomaterials possessed homogeneous and thin imprinted shells with a thickness of about 5 nm, stable crystalline phase, and superparamagnetism. The binding performance of the imprinted polymers was investigated through a series of adsorption experiments, which indicated that the products had satisfactory recognition ability for bovine hemoglobin and bovine serum albumin. The resultant nanoparticles were also successfully applied to simultaneously selective removal of two proteins from a real bovine blood sample.

Facile and green synthesis of polysaccharide-based magnetic molecularly imprinted nanoparticles for protein recognition

In this study, a facile and green approach to prepare core–shell magnetic molecularly imprinted nanoparticles based on a layer-by-layer assembly and surface imprinting technique was developed. Two types of natural polysaccharides (sodium alginate and chitosan) were firstly employed as hydrophilic double-monomers to synthesize water-compatible imprinted nanomaterials via a two-step self-assembly strategy for recognizing protein ovalbumin. The obtained products exhibited a desired level of magnetic susceptibility (45.30 emu g−1), resulting in the convenient and highly efficient separation process. The imprinted layer with thickness about 8 nm was homogeneously coated on the surface of Fe3O4, which was favorable for the fast mass transfer and rapid binding kinetics. The results of adsorption experiments showed that the saturation adsorption capacity of imprinted products could reach 92.22 mg g−1 within 40 min, which illustrated the high binding capacity. Meanwhile, the imprinting factor was as high as 4.07, demonstrating the potential selectivity of the prepared products. More importantly, the test of validation suggested that the proposed strategy would be a general method for imprinting different proteins in aqueous media by virtue of the peculiarity of polysaccharides as well as the efficient preparation process.