Improved detection and recognition of glycoproteins using fluorescent polymers with a molecular imprint based on glycopeptides.

Highly specific novel glycopeptide-based fluorescent molecularly imprinting polymers (g-FMIPs) were constructed to recognize and determine the target glycoprotein in complex biological samples. The glycopeptide of ovalbumin (OVA), with the unique structural characteristics of glycan and peptide, and potential application in improving the specificity recognition of g-FMIPs, was selected as the template molecule. The nitrogen-doped graphene quantum dots (N-GQDs) were introduced for fluorescence response. The obtained g-FMIPs possessed rapid binding kinetics and high adsorption capacity. Notably, the g-FMIPs exhibited remarkable selectivity and sensitivity with a high imprinting factor of 6.57, good linearity of 0.625 - 5.00 µM, and limit of detection of 0.208 µM. After treatment with g-FMIPs, the concentration of OVA in eluted solution was 1.07 µM. The obtained recoveries at 1.43 µM, 2.86 µM, and 4.29 µM spiked concentrations were 97.2%, 93.5%, and 101%, respectively, and the relative standard deviations were 2.6%, 4.2%, and 1.1%, respectively. In summary, the proposed strategy will expand the MIPs construction method and its application prospects in precision recognition and sensitive detection of trace glycoproteins from complex biosamples.

Surface-imprinted magnetic particles for highly selective sulfonamides recognition prepared by reversible addition fragmentation chain transfer polymerization.

In this work, novel magnetic molecularly imprinted polymers (MMIPs) were prepared by reversible addition fragmentation chain transfer (RAFT) polymerization using sulfamerazine as the template. With the controlled/living property of RAFT polymerization, the resulting MMIPs showed high selectivity for sulfonamides recognition. The MMIPs were characterized by transmission electron microscopy, Fourier transform infrared, vibrating sample magnetometer, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The static and selectivity binding experiments demonstrated the desirable adsorption capacity and high selectivity of the MMIPs. The developed MMIPs were used as the solid-phase extraction sorbents to selectively extract four sulfonamides from aqueous solution. The recoveries of the spiked pond water ranged from 61.2 to 94.1% with RSD lower than 6.5%. This work demonstrated a versatile approach for the preparation of well-constructed MMIPs for application in the field of solid-phase extraction.

Development and characterization of magnetic molecularly imprinted polymers for the selective enrichment of endocrine disrupting chemicals in water and milk samples.

Analyses of four endocrine disrupting chemicals (EDCs) in water and milk samples were undertaken by using magnetic molecularly imprinted polymers (MMIPs). These were prepared via the surface molecular imprinting technique using super paramagnetic core-shell nanoparticle as support. Diethylstilbestrol (DES), which is a typical EDC, was employed as the template molecule. The obtained MMIPs were characterized using transmission electron microscope, Fourier transform infrared, X-ray diffraction, and vibrating sample magnetometer. Accordingly, the adsorption capacity and selectivity of prepared MMIPs were investigated. The binding isotherms were obtained for DES and fitted by the Freundlich isotherm model. A corresponding analytical method to determine four EDCs was developed. The recoveries of the spiked samples in pond water and pure milk range from 67.8 to 93.2% and from 65.3 to 92.5%, respectively. Coupled with high-performance liquid chromatography analysis, the prepared MMIPs were successfully applied to the analysis of EDCs in water and milk samples.

Preparation of molecularly imprinted polymers based on magnetic nanoparticles for the selective extraction of protocatechuic acid from plant extracts.

In this study, highly selective core-shell molecularly imprinted polymers on the surface of magnetic nanoparticles were prepared using protocatechuic acid as the template molecule. The resulting magnetic molecularly imprinted polymers were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and vibrating sample magnetometry. The binding performances of the prepared materials were evaluated by static and selective adsorption. The binding isotherms were obtained for protocatechuic acid and fitted by the Langmuir isotherm model and Freundlich isotherm model. Furthermore, the resulting materials were used as the solid-phase extraction materials coupled to high-performance liquid chromatography for the selective extraction and detection of protocatechuic acid from the extracts of Homalomena occulta and Cynomorium songaricum with the recoveries in the range 86.3-102.2%.

Rational construction of fluorescent molecular imprinted polymers for highly efficient glycoprotein detection.

The enrichment of glycoproteins by fluorescence molecular imprinting has shown an attractive application prospect, however, its specificity and sensitivity in actual sample analysis remain a significant challenge. In this work, a novel fluorescent molecular imprinted nanoplatform (MMIPs@QDs) was constructed for the efficient recognition and determination of glycoproteins by combining the glycopeptide template and the post-imprinting modification of nitrogen-doped graphene quantum dots. The synthetic MMIPs@QDs exhibited high adsorption capacity and rapid binding kinetics. Satisfying selectivity and sensitivity were obtained using MMIPs@QDs, with an imprinting factor of 7.71 and a limit of detection of 0.20 µg mL-1, respectively. The efficiency and applicability of this proposed method were validated by the detection of ovalbumin in egg white samples, showed high recoveries (94.3%-100.2%) and acceptable relative standard deviation (1.79%-7.36%). This fluorescent molecular imprinted nanoplatform provides a new approach to address the limitations of existing protein detection techniques.

Open syntaxin overcomes exocytosis defects of diverse mutants in C. elegans.

Assembly of SNARE complexes that mediate neurotransmitter release requires opening of a 'closed' conformation of UNC-64/syntaxin. Rescue of unc-13/Munc13 mutant phenotypes by overexpressed open UNC-64/syntaxin suggested a specific function of UNC-13/Munc13 in opening UNC-64/ syntaxin. Here, we revisit the effects of open unc-64/syntaxin by generating knockin (KI) worms. The KI animals exhibit enhanced spontaneous and evoked exocytosis compared to WT animals. Unexpectedly, the open syntaxin KI partially suppresses exocytosis defects of various mutants, including snt-1/synaptotagmin, unc-2/P/Q/N-type Ca2+ channel alpha-subunit and unc-31/CAPS, in addition to unc-13/Munc13 and unc-10/RIM, and enhanced exocytosis in tom-1/Tomosyn mutants. However, open syntaxin aggravates the defects of unc-18/Munc18 mutants. Correspondingly, open syntaxin partially bypasses the requirement of Munc13 but not Munc18 for liposome fusion. Our results show that facilitating opening of syntaxin enhances exocytosis in a wide range of genetic backgrounds, and may provide a general means to enhance synaptic transmission in normal and disease states.

Synthesis of magnetic molecularly imprinted polymers by reversible addition fragmentation chain transfer strategy and its application in the Sudan dyes residue analysis.

Magnetic molecularly imprinted polymers (MMIPs) have become a hotspot owing to the dual functions of target recognition and magnetic separation. In this study, the MMIPs were obtained by the surface-initiated reversible addition fragmentation chain transfer (RAFT) polymerization using Sudan I as the template. The resultant MMIPs were characterized by transmission electron microscope, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, vibrating sample magnetometer, and X-ray diffraction. Benefiting from the controlled/living property of the RAFT strategy, the uniform MIP layer was successfully grafted on the surface of RAFT agent-modified Fe3O4@SiO2 nanoparticles, favoring the fast mass transfer and rapid binding kinetics. The developed MMIPs were used as the solid-phase extraction sorbents to selectively extract four Sudan dyes (Sudan I, II, III, and IV) from chili powder samples. The recoveries of the spiked samples in chili powder samples ranged from 74.1 to 93.3% with RSD lower than 6.4% and the relative standard uncertainty lower than 0.029. This work provided a good platform for the extraction and removal of Sudan dyes in complicated matrixes and demonstrated a bright future for the application of the well-constructed MMIPs in the field of solid-phase extraction.

Preparation of magnetic molecularly imprinted polymer for selective recognition of resveratrol in wine.

The magnetic molecularly imprinted polymers (MMIPs) for resveratrol were prepared by using surface molecular imprinting technique with a super paramagnetic core-shell nanoparticle as a supporter. Rhapontigenin, which is the analogues of resveratrol, was selected as dummy template molecules to avoid the leakage of trace amount of resveratrol. Acrylamide and ethylene glycol dimethacrylate were chosen as functional monomers and cross-linker, respectively. The obtained MMIPs were characterized by using scanning electron microscopy, Fourier transform infrared spectrum, X-ray diffraction and vibrating sample magnetometer. High performance liquid chromatography was used to analyze the target analytes. The resulting MMIPs exhibited high saturation magnetization of 53.14emug(-1) leading to the fast separation. The adsorption test showed that the MMIPs had high adsorption capacity for resveratrol and contained homogeneous binding sites. The MMIPs were employed as adsorbent of solid phase extraction for determination of resveratrol in real wine samples, and the recoveries of spiked samples ranged from 79.3% to 90.6% with the limit of detection of 4.42ngmL(-1). The prepared MMIPs could be employed to selectively pre-concentrate and determine resveratrol from wine samples.