The preparation of a boronate affinity-based controlled oriented imprinting coating on a silica nanoparticle surface for the separation and purification of shikimic acid in herbal medicine.

Shikimic acid (SA) is one of the most effective drugs against the A (H1N1) virus and has high medicinal value. Additionally, it has the ability to generate non-toxic herbicides and antimicrobial medications. The extraction from plants has proven to be the main route of production of SA with economic benefits and environmental efficiency. Therefore, it is necessary to perform purification of SA from these herbal medicines before quantifying it. In this study, researchers employed a boronate affinity-based controlled oriented surface imprinting technique to produce molecularly imprinted polymers (MIPs) as highly effective solid phase extraction (SPE) adsorbents for the isolation and purification of SA. 3-Fluoro-4-formylphenylboronic acid functionalized silica nanoparticles were used as supporting materials for immobilizing SA. Poly(2-anilinoethanol) with a higher hydrophilic domain can be used as an effective imprinting coating. The prepared SA-imprinted silica nanoparticles exhibited several significant results, such as good specificity, high binding capacity (39.06 ± 2.24 mg g-1), moderate binding constant (6.61 × 10-4 M-1), fast kinetics (8 min) and low binding pH (pH 5.0) toward SA. The replication of SA-imprinted silica nanoparticles was deemed satisfactory. The SA-imprinted silica nanoparticles could be still reused after seven adsorption-desorption cycles, which indicated high chemical stability. In addition, the recoveries of the proposed method for SA at three spiked level analysis in star aniseed and meadow cranesbill were 96.2% to 109.0% and 91.6% to 103.5%, respectively. The SA-imprinted silica nanoparticles that have been prepared are capable of identifying the target SA in real herbal medicines. Our approach makes sample pre-preparation simple, fast, selective and efficient.

Multiplexed colorimetry collaborated with smartphone-based image analysis for simultaneous and fast visualization of dyes in both environmental and food samples.

In this work, a multiplexed colorimetric strategy was initiated for simultaneous and fast visualization of dyes using low-cost and easy-to-prepare indicator papers as sorbents. Response surface methodology (RSM) was employed to model statistically and optimize the process variables for dyes extraction and colorimetric assays. Multiplexed colorimetry was realized by virtue of synchronous color alignments from different dimensions of multiple dyes co-stained colorimetric cards under RSM-optimized conditions, and smartphone-based image analysis was subsequently performed from different modes to double-check the credibility of colorimetric assays. As concept-to-proof trials, simultaneous visualization of dyes in both beverages and simulated dye effluents was experimentally proved with results highly matched to HPLC or spiked amounts at RSM-predicted staining time as short as 50 s ∼3 min, giving LODs as low as 0.97 ± 0.22/0.18 ± 0.08 µg/mL (tartrazine/brilliant blue) for multiplexed colorimetry, which much lower than those obtained by single colorimetry. Since this is the first case to propose such a RSM-guided multiplexed colorimetric concept, it will provide a reference for engineering of other all-in-one devices which can realize synchronous visualization applications within limited experimental steps.

Branched polyethylenimine-assisted boronic acid functionalized magnetic nanoparticles for highly efficient capture of lincomycin and clindamycin.

As lincosamide antibiotics, lincomycin and clindamycin are widely used in the drug manufacturing industry for the health of human beings and animals. Thus, the quantitative detection of them in real samples is of great significance. Due to the presence of complex interfering components in actual samples, the separation and enrichment of lincomycin and clindamycin prior to analysis are key. Therefore, it is necessary to develop a non-complex, cost-effective enrichment method for them. A five- or six-membered boronic cyclic ester is formed through boronate affinity materials binding a cis-diol-containing compound in aqueous media, which is a reversible reaction. However, low binding capacity and affinity, and high binding pH of boronate affinity materials are key concerns. In this study, polyethylenimine-assisted 3-fluoro-4-formylphenylboronic acid functionalized magnetic nanoparticles were developed to capture efficiently cis-diol-containing lincomycin and clindamycin under neutral conditions. Thereinto, polyethylenimine (PEI) was applied as a scaffold to amplify the number of boronic acid moieties. And 3-fluoro-4-formylphenylboronic acid was used as an affinity ligand due to its excellent water solubility and low pKa value toward lincomycin and clindamycin. The results indicated that the prepared branched boronic acid-functionalized MNPs provided high binding capacity and fast binding kinetics under neutral conditions. Furthermore, the obtained MNPs exhibited relatively high binding affinity (Kd ≈ 10-4 M) and low binding pH (pH ≥ 6.0).

Boronate affinity-based template-immobilization surface imprinted quantum dots as fluorescent nanosensors for selective and sensitive detection of myricetin.

In order to prepare a kind of efficient fluorescence sensors for determination of cis-diol-containing flavonoids, novel imprinted quantum dots for myricetin (Myr) were prepared based on boronate affinity-based template-immobilization surface imprinting. The obtained boronate affinity-based surface imprinted silica (imprinted APBA-functionalized CdTe QDs) was used as recognition elements. The quantum dots were used as signal-transduction materials. Under the optimum conditions, according to fluorescence quenching of imprinted APBA-functionalized CdTe QDs by Myr, the imprinting factor (IF) for Myr was evaluated to be 7.88. The result indicated that the boronate affinity functionalized quantum dots coated with imprinted silica were successfully prepared. The prepared imprinted APBA-functionalized CdTe QDs exhibited good sensitivity and selectivity for Myr. The fluorescence intensity was inversely proportional to the concentration of Myr in the 0.30-40 µM concentration range. And its detection limit was obtained to be 0.08 µM. Using the fluorescence sensors, the detection of Myr in real samples was successfully carried out, and the concentration of Myr in green tea and apple juice samples was evaluated to be 2.26 mg/g and 0.73 mg/g, respectively. The recoveries for the spiked green tea and apple juice samples were 95.2-105.0% and 91.5-111.0%, respectively. This study also provides an efficient fluorescent detection method for cis-diol-containing flavonoids in real samples.

6-Aminopyridine-3-boronic acid functionalized magnetic nanoparticles for highly efficient enrichment of cis-diol-containing biomolecules.

Boronate affinity materials, as efficient sorbents for extraction, separation and enrichment of cis-diol-containing biomolecules, have attracted more and more attention in recent years. However, conventional boronate affinity materials require a basic binding pH (usually 8.5), which gives rise to not only inconvenience in operation but also the risk of degradation of labile compounds, and suffer from low binding affinity, which make the extraction of cis-diol-containing compounds of low concentration difficult or impossible. In order to reduce the binding pH to neutral or acidic conditions and improve binding affinity, we present a type of material, 6-aminopyridine-3-boronic acid functionalized magnetic nanoparticles, with affinity towards cis-diol-containing biomolecules. 6-Aminopyridine-3-boronic acid, exhibiting low binding pH, high affinity and excellent water solubility toward cis-diol-containing compounds, was first employed as an affinity ligand. The result indicated that the boronate affinity MNPs exhibited low binding pH (5.0) and high binding affinity toward cis-diol-containing biomolecules. Such a property enabled the selective extraction of cis-diol-containing biomolecules with low concentration under neutral or acidic conditions. This feature greatly favored the selective enrichment of cis-diol-containing biomolecules with low concentration from real samples. The feasibility for practical applications was demonstrated with the selective enrichment of cis-diol-containing biomolecules with low concentration in a human urine sample.

Determination of cis-diol-containing flavonoids in real samples using boronate affinity quantum dots coated with imprinted silica based on controllable oriented surface imprinting approach.

Novel boronate affinity imprinted quantum dots (BA-CdTe@MIPs QDs) were used to develop a selective and sensitive fluorescent nanosensor for determination of cis-diol-containing flavonoids such as quercetin (Qu), baicalein (Bai) and luteolin (Lut) based on controllable oriented surface imprinting approach. The boronate affinity imprinted silica was used as recognition elements. Under the optimum conditions, the imprinting factor (IF) for Qu, Bai and Lut was evaluated to be 9.42, 6.58 and 10.91, respectively. The results indicated that the boronate affinity quantum dots coated with imprinted silica were successfully prepared. The obtained BA-CdTe@MIPs QDs provided high selectivity and high sensitivity for cis-diol-containing flavonoids such as quercetin and luteolin. The BA-CdTe@MIPs QDs exhibited linear decrease in fluorescence intensity with the increase of concentration of quercetin in the 0.05-25 µM concentration range. The detection limit (LOD) is evaluated to be 0.02 µM. The obtained fluorescent nanosensor could be successfully applied to efficient detection of cis-diol-containing flavonoids in onion skin and human urine samples. The recoveries for the spiked onion skin and urine samples were evaluated to be 83.50-104.00% and 86.67-105.00%, respectively. Clearly, this study provides a rapid and efficient fluorescent detection tool for cis-diol-containing flavonoids in real samples.

Branched polyethyleneimine-assisted 3-carboxybenzoboroxole improved Wulff-type boronic acid functionalized magnetic nanoparticles for the specific capture of cis-diol-containing flavonoids under neutral conditions.

Flavonoids have shown a variety of biological activities such as antimicrobial, antibacterial, antifungal, antiviral, antiinflammatory, antitumor, antiatherogenic, and antihyperglycemic activities. A lot of important flavonoids contain cis-diols such as rutin (Ru), quercetin (Qu), luteolin (Lu), myricetin (Myr) and baicalein (Ba) and so on. It is necessary to establish a simple, low-cost and efficient purification method for cis-diol-containing flavonoids from plant extracts. Boronate affinity materials are able to reversibly bind the cis-diols via boronic acids by forming a five- or six-membered boronic cyclic ester in aqueous media. However, conventional boronate affinity materials have to be used in alkaline media, which can lead to the oxidation of cis-diols in compounds. In this study, the polyethyleneimine (PEI)-assisted 3-carboxybenzoboroxole-functionalized magnetic nanoparticles (MNPs) were prepared to achieve efficient capture of cis-diol-containing flavonoids under neutral conditions. Branched PEI was applied as a scaffold to amplify the number of boronic acid moieties, while 3-carboxybenzoboroxole, exhibiting high affinity and excellent water solubility toward flavonoids, was used as an affinity ligand. The prepared boronate affinity MNPs exhibited high binding capacity and fast binding kinetics (equilibrium in 3 min) under neutral conditions. In addition, the obtained boronate affinity MNPs exhibited high binding affinity (K d ≈ 10-4 M), low binding pH (pH ≥ 6.0) and tolerance of the interference to abundant sugars.

Efficient vitamin B12-imprinted boronate affinity magnetic nanoparticles for the specific capture of vitamin B12.

Vitamin B12 (VB12) has an important function in human physiology. However, analysis of VB12 at natural levels in foods or biological samples is difficult because of its very low concentration level and the presence of high-abundance components which can interfere with the measuring system. Thus, it is essential to develop efficient and selective enrichment approaches for VB12. Molecularly imprinted polymers (MIPs) have important applications from separation and sensing to catalysis. However, there is no report on the preparation of MIPs for VB12. Here, we use boronate affinity-based oriented surface imprinting to prepare MIPs for VB12. A VB12 template was first covalently immobilized onto the surface of boronic acid functionalized magnetic nanoparticles. Subsequently, a thin imprinting coating of poly(2-anilinoethanol) was formed to cover the substrate surface via in-water polymerization. After removing the template, 3D cavities complementary to the molecular size and shape of the template were formed in the imprinting layer. The imprinting coating was highly hydrophilic and presented limited residual boronic acid, thus non-specific binding was avoided. The prepared MIPs exhibited several highly favorable features, including excellent specificity, high binding strength and low binding pH. The prepared MIPs were successfully applied to the analysis of VB12 in human milk.

Efficient synthesis of riboflavin-imprinted magnetic nanoparticles by boronate affinity-based surface imprinting for the selective recognition of riboflavin.

Riboflavin (vitamin B2), a cis-diol-containing compound, is an essential vitamin for maintaining human health mainly in energy metabolism and is a critical component of enzyme cofactors and flavoproteins. Thus, the determination of riboflavin in food products is essential in riboflavin-fortified foods. However, analysis of riboflavin at natural levels in foods or biological samples is difficult because of its very low concentration level and the presence of undesirable matrix effects which could interfere with the measuring system. Thus, it is essential to develop efficient and selective enrichment approaches for riboflavin. Molecularly imprinted polymers can be well used for riboflavin extraction and pre-concentration from food samples. In this study, we present riboflavin-imprinted magnetic nanoparticles as an ideal sorbent for the selective enrichment of riboflavin followed by direct fluorometric determination. The riboflavin-imprinted magnetic nanoparticles were prepared according to a newly reported strategy, called boronate affinity-based surface initiated imprinting. Magnetic nanoparticles and vinylphenylboronic acid were used as supporting materials and a functional monomer, respectively. The prepared riboflavin-imprinted magnetic nanoparticles exhibited several significant advantages, such as excellent selectivity, high binding affinity and low binding pH toward riboflavin, which made the molecularly imprinted material become an ideal sorbent for the selective enrichment of riboflavin. The prepared riboflavin-imprinted magnetic nanoparticles were successfully applied to the analysis of riboflavin in milk.

Branched polyethyleneimine-assisted boronic acid-functionalized silica nanoparticles for the selective enrichment of trace glycoproteins.

Boronate affinity materials have attracted more and more attention in extraction, separation and enrichment of glycoproteins due to the important roles that glycoproteins take on in recent years. However, conventional boronate affinity materials suffer from low binding affinity mainly because of the use of single boronic acids. This makes the extraction of glycoproteins of trace concentration become rather difficult or impossible. Here we present a novel boronate avidity material, polyethyleneimine (PEI)-assisted boronic acid-functionalized silica nanoparticles (SNPs). Branched PEI was applied as a scaffold to amplify the number of boronic acid moieties. While 3-carboxybenzoboroxole, exhibiting high affinity and excellent water solubility toward glycoproteins, was used as an affinity ligand. Due to the PEI-assisted synergistic multivalent binding, the boronate avidity SNPs exhibited strong binding strength toward glycoproteins with dissociation constants of 10-7 M, which was the highest among reported boronic acid-functionalized materials that can be applied for glycoproteomic analysis. Such a high avidity enabled the selective extraction of trace glycoproteins as low as 0.4 pg/mL. This feature greatly favored the selective enrichment of trace glycoproteins from real samples. Meanwhile, the boronate avidity SNPs was tolerant of the interference of abundant sugars. In addition, the PEI-assisted boronate avidity SNPs exhibited high binding capacity and low binding pH. The feasibility for practical applications was demonstrated with the selective enrichment of trace glycoproteins in human saliva.

Efficient preparation of surface imprinted magnetic nanoparticles using poly (2-anilinoethanol) as imprinting coating for the selective recognition of glycoprotein.

In view of the significance of glycoprotein biomarkers for early clinical diagnostics and treatments of diseases, it is essential to develop efficient and selective enrichment approaches for glycoproteins. Molecularly imprinted polymers (MIPs) have found important applications for separation and enrichment of glycoproteins. In this study, we use boronate affinity-based controllable oriented surface imprinting to prepare glycoprotein-imprinted magnetic nanoparticles. A glycoprotein was first immobilized onto the surface of boronic acid functionalized magnetic nanoparticles by boronate affinity. Subsequently, self-polymerization of 2-anilinoethanol was carried out to form thin imprinting coating on the magnetic nanoparticles surface with appropriate thickness. After removing the template with an acidic solution containing sodium dodecyl sulfate, 3D cavities complementary to the template were efficiently formed in the imprinting layer. The imprinting coating was highly hydrophilic and presented limited residual boronic acid, thus non-specific binding was avoided. Using horseradish peroxidase as a model target, the effects of imprinting conditions on the properties and performance of the prepared MIPs were investigated. The obtained MIPs exhibited several highly favorable features, including excellent specificity, high binding strength and low binding pH. The MIPs were successfully applied to the analysis of transferrin (TRF) in human serum.

Branched polyethyleneimine-assisted boronic acid-functionalized magnetic nanoparticles for the selective enrichment of trace glycoproteins.

Boronate affinity materials, as efficient sorbents for extraction, separation and enrichment of glycoproteins, have attracted more and more attention in recent years. However, conventional boronate affinity materials suffer from low binding affinity due to the use of single boronic acids, which makes the extraction of glycoproteins in trace concentration rather difficult or impossible. Here we present a type of high boronate avidity material, polyethyleneimine (PEI)-assisted boronic acid-functionalized magnetic nanoparticles (MNPs). Branched PEI was used as a scaffold to amplify the number of boronic acid moieties, while 2,4-difluoro-3-formyl-phenylboronic acid (DFFPBA), exhibiting high affinity and excellent water solubility toward cis-diol-containing compounds, was employed as an affinity ligand. Due to the PEI-assisted synergistic multivalent binding, the boronate avidity MNPs exhibited a high binding affinity toward glycoproteins with dissociation constants of 10-6-10-7 M, which was the highest among the reported boronic acid-functionalized materials that can be applied for a glycoproteomic analysis. Such an avidity enabled the selective extraction of trace glycoproteins as low as 2 × 10-15 M. This feature greatly favored the selective enrichment of trace glycoproteins from real samples. Meanwhile, the boronate avidity MNPs were tolerant to the interference of abundant sugars. In addition, the PEI-based boronate avidity MNPs exhibited high binding capacity and low binding pH. The feasibility for practical applications was demonstrated with the selective enrichment of trace glycoproteins in human saliva.

Coupling of metal-organic frameworks-containing monolithic capillary-based selective enrichment with matrix-assisted laser desorption ionization-time-of-flight mass spectrometry for efficient analysis of protein phosphorylation.

Protein phosphorylation is a major post-translational modification, which plays a vital role in cellular signaling of numerous biological processes. Mass spectrometry (MS) has been an essential tool for the analysis of protein phosphorylation, for which it is a key step to selectively enrich phosphopeptides from complex biological samples. In this study, metal-organic frameworks (MOFs)-based monolithic capillary has been successfully prepared as an effective sorbent for the selective enrichment of phosphopeptides and has been off-line coupled with matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) for efficient analysis of phosphopeptides. Using s-casein as a representative phosphoprotein, efficient phosphorylation analysis by this off-line platform was verified. Phosphorylation analysis of a nonfat milk sample was also demonstrated. Through introducing large surface areas and highly ordered pores of MOFs into monolithic column, the MOFs-based monolithic capillary exhibited several significant advantages, such as excellent selectivity toward phosphopeptides, superb tolerance to interference and simple operation procedure. Because of these highly desirable properties, the MOFs-based monolithic capillary could be a useful tool for protein phosphorylation analysis.

Investigation on the interaction between isorhamnetin and bovine liver catalase by spectroscopic techniques under different pH conditions.

The binding of isorhamnetin to bovine liver catalase (BLC) was first investigated at 302, 310 and 318 K at pH 7.4 using spectroscopic methods including fluorescence spectra, circular dichroism (CD) and UV-vis absorption. Spectrophotometric observations are rationalized mainly in terms of a static quenching process. The binding constants and binding sites were evaluated by fluorescence quenching methods. Enzymatic activity of BLC in the absence and presence of isorhamnetin was measured using a UV/vis spectrophotometer. The result revealed that the binding of isorhamnetin to BLC led to a reduction in the activity of BLC. The positive entropy change and enthalpy change indicated that the interaction of isorhamnetin with BLC was mainly driven by hydrophobic forces. The distance r between the donor (BLC) and acceptor (isorhamnetin) was estimated to be 2.99 nm according to fluorescence resonance energy transfer. Fluorescence, synchronous fluorescence, and CD spectra showed no obvious change in the conformation of BLC upon the binding of isorhamnetin. In addition, the influence of pH on the binding of isorhamnetin to BLC was investigated and the binding ability of the drug to BLC deceased under other pH conditions (pH 9.0, 6.5, 5.0, 3.5, or 2.0) as compared with that at pH 7.4. Copyright © 2016 John Wiley & Sons, Ltd.

Coupling of Phosphate-Imprinted Mesoporous Silica Nanoparticles-Based Selective Enrichment with Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry for Highly Efficient Analysis of Protein Phosphorylation.

Protein phosphorylation is a major post-translational modification and represents a ubiquitous mechanism for the cellular signaling of many different biological processes. Selective enrichment of phosphopeptides from the complex biological samples is a key step for the mass spectrometric (MS) analysis of protein phosphorylation. Herein, we present phosphate-imprinted mesoporous silica nanoparticles (MSNs) as an ideal sorbent for selective enrichment of phosphopeptides and an off-line combination with matrix-asisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) for highly efficient analysis of protein phosphorylation. The phosphate-imprinted MSNs were prepared according to a newly reported strategy called dual-template docking oriented molecular imprinting (DTD-OMI). The prepared molecularly imprinted mesoporous material exhibited several significant merits, such as excellent selectivity toward phosphopeptides, tolerance to interference, fast binding equilibrium, and large binding capacity, which made the molecularly imprinted mesoporous material an ideal sorbent for selective enrichment of phosphopeptides. Using ß-casein as a representative phosphoprotein, highly efficient phosphorylation analysis by the off-line platform was verified. Phosphorylation analysis of a nonfat milk sample was also well demonstrated. Because of their highly desirable properties, the phosphate-imprinted MSNs could find more applications in the analysis of protein phosphorylation.

Boronate affinity materials for separation and molecular recognition: structure, properties and applications.

Boronate affinity materials, as unique sorbents, have emerged as important media for the selective separation and molecular recognition of cis-diol-containing compounds. With the introduction of boronic acid functionality, boronate affinity materials exhibit several significant advantages, including broad-spectrum selectivity, reversible covalent binding, pH-controlled capture/release, fast association/desorption kinetics, and good compatibility with mass spectrometry. Because cis-diol-containing biomolecules, including nucleosides, saccharides, glycans, glycoproteins and so on, are the important targets in current research frontiers such as metabolomics, glycomics and proteomics, boronate affinity materials have gained rapid development and found increasing applications in the last decade. In this review, we critically survey recent advances in boronate affinity materials. We focus on fundamental considerations as well as important progress and new boronate affinity materials reported in the last decade. We particularly discuss on the effects of the structure of boronate ligands and supporting materials on the properties of boronate affinity materials, such as binding pH, affinity, selectivity, binding capacity, tolerance for interference and so on. A variety of promising applications, including affinity separation, proteomics, metabolomics, disease diagnostics and aptamer selection, are introduced with main emphasis on how boronate affinity materials can solve the issues in the applications and what merits boronate affinity materials can provide.

Dual-template docking oriented molecular imprinting: a facile strategy for highly efficient imprinting within mesoporous materials.

We present a new strategy, called dual-template docking oriented molecular imprinting (DTD-OMI), for facile and highly efficient imprinting within mesoporous materials. As compared with bulk imprinting, which is a widely used strategy, DTD-OMI did not require additional steps, but provided significantly improved imprinting efficiency and binding properties.

Highly Efficient Solid-Phase Labeling of Saccharides within Boronic Acid Functionalized Mesoporous Silica Nanoparticles.

Labeling is critical for the detection, quantitation, and structural identification of saccharides. However, conventional liquid-phase labeling suffers from apparent disadvantages, such as time-consuming, the presence of excessive labeling reagent, and high applicable saccharide concentration. A solid-phase approach is presented for highly efficient labeling of saccharides, using boronic acid functionalized mesoporous silica nanoparticles (MSNs) as a selective extraction sorbent and nanoscale reactor. The solid-phase labeling approach exhibited several significant advantages, including: much faster reaction speed (taking only 2 min), high product purity, and much lower applicable saccharide concentration (four orders of magnitude lower than that of liquid-phase labeling). Thus, this labeling approach opens up new avenues to the facile and efficient labeling of saccharides.

Pattern recognition of monosaccharides via a virtual lectin array constructed by boronate affinity-based pH-featured encoding.

Lectin array is an important tool in the fields of carbohydrate chemistry, glycobiology, and glycomics. Because natural lectins are associated with some apparent disadvantages such as tedious purification and easy loss of activity, artificial materials are applied to overcome such shortages by mimicking and replacing lectins in an artificial lectin array, among which boronate affinity-based materials are very outstanding and widely used. However, complicated synthetic works are often involved to design and create boronate affinity-based lectin-mimics. In this work, a facile and novel method was proposed to establish a virtual lectin array based on boronate affinity-based pH-featured encoding for discrimination of monosaccharides by pattern recognition. The dependence of boronate affinity on environmental pH was selected to encode each monosaccharide for feature generation, and the pH-featured encoding was used to construct the virtual lectin array. On the basis of the virtual array, pattern recognition algorithms were applied for data analysis. Monosaccharides were discriminated by principal component analysis, and the relations in the virtual lectin array were unraveled by cluster analysis. In this proof-of-concept work, without complicated synthesis or preparation, the proposed method was successful in mimicking lectin array and discriminating nine elementary monosaccharides found in nature, and it was also a new way of encoding in expanding the applications of boronate affinity-based materials and methods in the field of biomimetics.

A high boronate avidity monolithic capillary for the selective enrichment of trace glycoproteins.

Boronate affinity materials, as effective sample enrichment sorbents for glycoproteomic analysis, have attracted increasing attention in recent years. However, most of boronate affinity materials suffer from an apparent limitation, limited binding strength. As a result, extraction of glycoproteins of trace concentration is rather difficult or impossible. In this study, we present a high boronate avidity monolithic capillary. Branched polyethyleneimine (PEI) was used as a scaffold to amplify the number of boronic acid moieties. While 2,4-difluoro-3-formyl-phenylboronic acid (DFFPBA), which exhibited ultrahigh affinity toward cis-diol-containing compounds, was employed as an affinity ligand. Due to the PEI-assisted synergistic multivalent binding, the monolithic column exhibited high boronate avidity toward glycoproteins, with binding constants of 10(-6)-10(-7)M. Such binding strength was the highest among already reported boronic acid-functionalized materials that can be used for glycoproteomic analysis. Besides, the boronate avidity monolithic column exhibited one additional beneficial feature, lowered binding pH (≥6.5). These features greatly favored the selective enrichment of trace glycoproteins from real samples. The feasibility for practical applications was demonstrated with the selective enrichment of trace glycoproteins in human saliva. As compared with other boronate avidity/affinity materials, the boronate avidity monolithic capillary exhibited the best performance.