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

Fabrication of micron-sized boronate-decorated polyethyleneimine-grafted magnetic agarose beads for specific enrichment of ribonucleic acid

Exploiting high-performance magnetic beads for specific enrichment of ribonucleic acid (RNA) has important significance in the biomedical research field. Herein, a simple strategy was proposed for fabricating boronate-decorated polyethyleneimine-grafted magnetic agarose beads (BPMAB), which can selectively isolate cis-diol-containing substances through boronate affinity. The size of the basic magnetic agarose beads was controlled through the emulsification of the water-in-oil emulsion with a high-speed shear machine, which enhanced the specific surface area of BPMAB. Subsequently, to modify more boronic acid ligands, branched PEI with excellent hydrophilicity and numerous reaction sites was grafted. 2,4-Difluoro-3-formylphenyl boronic acid (2,4-DFPBA) was covalently immobilized for selectively capturing cis-diol-containing substances under physiological condition (pH 7.4). The BPMAB with a diameter range from 1.86 μm to 11.60 μm possessed clearly spherical structure, and excellent magnetic responsiveness and suspension ability in aqueous solution. β-Nicotinamide adenine dinucleotide (β-NAD), a short-chain cis-diol carrying agent, was selected as a target molecule for evaluating the adsorption property of BPMAB and the maximum adsorption capacity of BPMAB for β-NAD could reach 205.11 mg g-1. In addition, the BPMAB as adsorbent was used to selectively enrich RNA from mammalian cells. The maximum adsorption capacity of BPMAB for RNA was 140.50 mg g-1. Under optimized conditions, the BPMAB-based MSPE successfully enriched the high-quality total RNA with 28S to 18S ribosomal RNA ratios ranging from 2.06 to 2.16. According to the PCR analysis of GADPH gene, the extracted total RNA was successfully reverse transcribed into cDNA. Therefore, we believe that the BPMAB-based MSPE could be applicable for the specific enrichment of RNA from complex biological systems.

Triazine-structured covalent organic framework nanosheets with inherent hydrophilicity for the highly efficient and selective enrichment of glycosylated peptides

Protein glycosylation plays a crucial role in various biological processes and is related to various diseases. Highly specific enrichment of glycopeptides before mass spectrometry detection is crucial for comprehensive glycoproteomic analysis. However, it still remains a great challenge due to the absence of affinity materials with excellent enrichment efficiency. In this work, a triazine structure linked by a -NH- bond of two-dimensional (2-D) covalent organic framework (COF) nanosheets was synthesized as an affinity adsorbent for the selective capture of glycopeptides. In particular, by introducing hydrophilic monomers via a bottom-up approach, the 2-D COF (denoted as NENP-1) nanosheets were provided with abundant amino groups and inherent hydrophilicity. Owing to the specific surface area and excessive accessible sites for hydrophilicity, the resulting NENP-1 nanosheets exhibited an outstanding glycopeptide enrichment efficiency from standard samples with a superior detection sensitivity (1 × 10-10 M), good enrichment selectivity (1 : 800, HRP tryptic digest to BSA protein), excellent binding capacity (100 mg g-1), great reusability, and recovery (60.2%). Furthermore, using the NENP-1 nanosheet adsorbent, twenty-four endogenous glycopeptides in the serum of patients with gastric cancer were successfully identified by LC-MS/MS technology, which illustrates a promising prospective of hydrophilic COF nanosheets in glycoproteomics research.

Dual-modal analysis of cis-diols in traditional Chinese medicine via boronic acid incorporated metal organic frameworks

In this study, a boronic acid incorporated metal organic frameworks (inBA-MIL-100) were prepared via metal-ligand-fragment co-assembly strategy. The prepared frameworks can be served either as enrichment sorbent or SALDI-MS matrix for cis-diol containing molecules. Thus, a dual-modal analysis of cis-diols in traditional Chinese medicine has been established. Several significant advantages of the proposed strategy have been experimentally demonstrated, including high selectivity, high binding capacity (70 mg/g), good generality (5-250 μg/mL for HPLC based sample preparation, 10-500 ng/mL for SALDI-MS), high sensitivity (LOD: 180 ng/mL for HPLC based sample preparation, 5 ng/mL for SALDI-MS) and reliable quantification (RSD<3 % for HPLC based sample preparation, RSD<12 % for SALDI-MS) performance. Finally, the successful analysis of various cis-diols (active component and mycotoxin) in various Chinese traditional medicine was also achieved.

Study on the creation of boronate affinity-based oriented imprinted silica nanoparticles and their selective recognition toward glycopeptide antibiotics in food and water

Taking into account the drug resistance of antibiotics, teicoplanin has been banned in the veterinary field. Also, it brings threat to people's health when they eat foods containing teicoplanin residue. In addition, the abuse of teicoplanin in humans and food animals also poses a potential risk to water. Therefore, it is crucial to purify teicoplanin from food before quantifying its amount. In this study, researchers employed boronate affinity-based controlled oriented surface imprinting technique to produce molecularly imprinted polymers (MIPs) for the isolation of teicoplanin. The 3-fluoro-4-formylphenylboronic acid-functionalized silica nanoparticle substrate was first used as the supporting material for immobilizing teicoplanin. Next, the substrate surface was coated with an imprinting coating whose thickness could be controlled, produced through the self-copolymerization of dopamine and m-aminophenylboronic acid (APBA) in water. After the template was removed, 3D cavities that matched the template were created in the imprinting layer. The prepared teicoplanin-imprinted silica nanoparticles exhibited several significant satisfactory results such as good specificity, high binding capacity (46.9 ± 2.3 mg g-1), moderate binding constant ((5.46 ± 0.18) × 10-5 M-1), fast kinetics (8 min) and low binding pH (pH 5.0) toward teicoplanin. The teicoplanin-imprinted silica nanoparticles could still be reused after seven cycles of adsorption-desorption, which indicated a high chemical stability. In addition, recoveries of the proposed method for teicoplanin at three spiked levels in milk and water ranged from 91.8 to 105.6% and 92.3 to 97.4%, respectively. The teicoplanin-imprinted silica nanoparticles are capable of identifying the target teicoplanin in real samples in a simple, fast, selective and efficient manner.

A double boronic acid affinity "sandwich" SERS biosensor based on magnetic boronic acid controllable-oriented imprinting for high-affinity biomimetic specific recognition and rapid detection of target glycoproteins

Transferrin (TRF), recognized as a glycoprotein clinical biomarker and therapeutic target, has its concentration applicable for disease diagnosis and treatment monitoring. Consequently, this study developed boronic acid affinity magnetic surface molecularly imprinted polymers (B-MMIPs) with pH-responsitivity as the "capture probe" for TRF, which have high affinity similar to antibodies, with a dissociation constant of (3.82 ± 0.24) × 10-8 M, showing 7 times of reusability. The self-copolymerized imprinted layer synthesized with dopamine (DA) and 3-Aminophenylboronic acid (APBA) as double monomers avoided nonspecific binding sites and produced excellent adsorption properties. Taking the gold nanostar (AuNS) with a branch tip "hot spot" structure as the core, the silver-coated AuNS functionalized with the biorecognition element 4-mercaptophenylboronic acid (MPBA) was employed as a surface-enhanced Raman scattering (SERS) nanotag (AuNS@Ag-MPBA) to label TRF, thereby constructing a double boronic acid affinity "sandwich" SERS biosensor (B-MMIPs-TRF-SERS nanotag) for the highly sensitive detection of TRF. The SERS biosensor exhibited a detection limit for TRF of 0.004 ng/mL, and its application to spiked serum samples confirmed its reliability and feasibility, demonstrating significant potential for clinical TRF detection. Moreover, the SERS biosensor designed in this study offers advantages in stability, detection speed (40 min), and cost efficiency. The portable Raman instrument for SERS detection fulfills the requirements for point-of-care testing.

Boronate crosslinking-based ratiometric electrochemical assay of glycated albumin

As a product of nonenzymatic glycation, glycated albumin (GA) is a promising serum marker for the short-term glycemic monitoring in patients with diabetes. On the basis of the boronate crosslinking (BCL)-enabled direct labeling of ferrocene (Fc) tags to the nonenzymatically glycated (NEG) sites, we report herein a novel aptamer-based ratiometric electrochemical (apt-REC) platform for the point-of-care (POC) assay of GA. This apt-REC platform is based on the recognition of GA proteins by the methylene blue (MB)-modified aptamer receptors and the labeling of the Fc tags to the NEG sites via the BCL. Using MB as the reference tag and Fc as the quantification tag, the ratio of the oxidation currents (i.e., IFc/IMB) can serve as the yardstick for the ratiometric assay of GA. Due to the presence of tens of the NEG sites, each GA protein can be labeled with tens of quantification tags, permitting the amplified assay in a simple, time-saving, and low-cost manner. The ratiometric signal exhibited a good linear response over the range from 0.1 to 100 μg/mL, with a detection limit of 45.5 ng/mL. In addition to the superior reproducibility and robustness, this apt-REC platform is highly selective (capable of discriminating GA against human serum albumin (HSA)) and applicable to GA assay in serum samples. Due to its low cost, high reproducibility and robustness, simple operation, and high sensitivity and selectivity, this apt-REC platform holds great promise in the POC assay of GA for diabetes management.

pH/H2O2 Cascade-Responsive Nanoparticles of Lipid-Like Prodrugs through Dynamic-Covalent and Coordination Interactions for Chemotherapy

Traditional lipid nanoparticles (LNPs) suffer from low drug loading capacity (DLC), weak stability, and lack of responsiveness. Conventional approaches to address these issues involve the synthesis of lipid-prodrug by incorporating responsive covalent linkers. However, such approaches often result in suboptimal sensitivity for drug release and undermine therapeutic effectiveness. Herein, the study reports a fundamentally different concept for designing lipid-like prodrugs through boron-nitrogen (B-N) coordination and dynamic covalent interaction. The 5-fluorouracil-based lipid-like prodrugs, featuring a borate ester consisting of a glycerophosphoryl choline head and a boronic acid-modified 5Fu/dodecanamine complex tail, are used to prepare pH/H2O2 cascade-responsive LNPs (5Fu-LNPs). The 5Fu-LNPs exhibit enhanced DLC and stability in a neutral physiological environment due to the B-N coordination and enhanced hydrophobicity. In tumors, acidic pH triggers the dissociation of B-N coordination to release prodrugs, which further responds to low H2O2 concentrations to release drugs, showcasing a potent pH/H2O2-cascade-responsive property. Importantly, 5Fu-LNPs demonstrate greater antitumor efficiency and lower toxicity compared to the commercial 5Fu. These results highlight 5Fu-LNPs as a safer and more effective alternative to chemotherapy. This work presents a unique LNP fabrication strategy that can overcome the limitations of conventional LNPs and broaden the range of intelligent nanomaterial preparation techniques.

ROS-responsive hydrogels: from design and additive manufacturing to biomedical applications

Hydrogels with intricate 3D networks and high hydrophilicity have qualities resembling those of biological tissues, making them ideal candidates for use as smart biomedical materials. Reactive oxygen species (ROS) responsive hydrogels are an innovative class of smart hydrogels, and are cross-linked by ROS-responsive modules through covalent interactions, coordination interactions, or supramolecular interactions. Due to the introduction of ROS response modules, this class of hydrogels exhibits a sensitive response to the oxidative stress microenvironment existing in organisms. Simultaneously, due to the modularity of the ROS-responsive structure, ROS-responsive hydrogels can be manufactured on a large scale through additive manufacturing. This review will delve into the design, fabrication, and applications of ROS-responsive hydrogels. The main goal is to clarify the chemical principles that govern the response mechanism of these hydrogels, further providing new perspectives and methods for designing responsive hydrogel materials.

Structure-Assisted Boronic Acid Implanted Mesoporous Metal-Organic Frameworks for Specific Extraction of cis-Diol Molecules

cis-Diol-containing molecules, an essential type of compounds in living organisms, have attracted intensive research interest from various fields. The analysis of cis-diol-containing molecules is still suffering from some drawbacks, including low abundance and abundant interference. Metal-organic frameworks (MOFs) have proven to be an ideal sorbent for sample preparation. However, most of the reported MOFs are mainly restricted to a microporous regime (pore size <2 nm), which greatly limits the application. Herein, a facile strategy is established to construction of boronate affinity MOFs via the postsynthetic ligand-exchange process. Owing to the fact that the ligand-exchange process was assisted by the structural integrity of the primitive metal-organic framework and the great compatibility of click chemistry, the obtained EPBA-PCN-333(Fe) is able to realize the maximum maintaining the porosity and crystallinity of the parent material. Several intriguing features of EPBA-PCN-333(Fe) (e.g., excellent selectivity, efficient diffusion, good accessibility, and size exclusion effect) are experimentally demonstrated via a series of cis-diol-containing molecules with different molecular sizes (small molecules, glycopeptides, and glycoproteins). The binding performance of EPBA-PCN-333(Fe) is evaluated by employing catechol as the test molecule (binding capacity: 0.25 mmol/g, LOD: 200 ng/mL). Finally, the real-world applications of EPBA-PCN-333(Fe) were demonstrated by the detection of nucleosides of human urine samples.

Site-Directed Electrochemical Grafting for Amplified Detection of Antibody Pharmaceuticals

Antibody pharmaceuticals have become the most popular immunotherapeutic drugs and are often administered with low serum drug dosages. Hence, the development of a highly sensitive method for the quantitative assay of antibody levels is of great importance to individualized therapy. On the basis of the dual signal amplification by the glycan-initiated site-directed electrochemical grafting of polymer chains (glyGPC), we report herein a novel strategy for the amplified electrochemical detection of antibody pharmaceuticals. The target of interest was affinity captured by a DNA aptamer ligand, and then the glycans of antibody pharmaceuticals were decorated with the alkyl halide initiators (AHIs) via boronate cross-linking, followed by the electrochemical grafting of the ferrocenyl polymer chains from the glycans of antibody pharmaceuticals through the electrochemically controlled atom transfer radical polymerization (eATRP). As the glycans can be decorated with multiple AHIs and the grafted polymer chains are composed of tens to hundreds of electroactive tags, the glyGPC-based strategy permits the dually amplified electrochemical detection of antibody pharmaceuticals. In the presence of trastuzumab (Herceptin) as the target, the glyGPC-based strategy achieved a detection limit of 71.5 pg/mL. Moreover, the developed method is highly selective, and the results of the quantitative assay of trastuzumab levels in human serum are satisfactory. Owing to its uncomplicated operation and cost-effectiveness, the glyGPC-based strategy shows great promise in the amplified electrochemical detection of antibody pharmaceuticals.

Comprehensive O-Glycan Analysis by Porous Graphitized Carbon Nanoliquid Chromatography-Mass Spectrometry

The diverse and unpredictable structures of O-GalNAc-type protein glycosylation present a challenge for its structural and functional characterization in a biological system. Porous graphitized carbon (PGC) liquid chromatography (LC) coupled to mass spectrometry (MS) has become one of the most powerful methods for the global analysis of glycans in complex biological samples, mainly due to the extensive chromatographic separation of (isomeric) glycan structures and the information delivered by collision induced fragmentation in negative mode MS for structural elucidation. However, current PGC-based methodologies fail to detect the smaller glycan species consisting of one or two monosaccharides, such as the Tn (single GalNAc) antigen, which is broadly implicated in cancer biology. This limitation is caused by the loss of small saccharides during sample preparation and LC. Here, we improved the conventional PGC nano-LC-MS/MS-based strategy for O-glycan analysis, enabling the detection of truncated O-glycan species and improving isomer separation. This was achieved by the implementation of 2.7 μm PGC particles in both the trap and analytical LC columns, which provided an enhanced binding capacity and isomer separation for O-glycans. Furthermore, a novel mixed-mode PGC-boronic acid-solid phase extraction during sample preparation was established to purify a broad range of glycans in an unbiased manner, including the previously missed mono- and disaccharides. Taken together, the optimized PGC nano-LC-MS/MS platform presents a powerful component of the toolbox for comprehensive O-glycan characterization.

Photonic Nanochains for Continuous Glucose Monitoring in Physiological Environment

Diabetes is a common disease that seriously endangers human health. Continuous glucose monitoring (CGM) is important for the prevention and treatment of diabetes. Glucose-sensing photonic nanochains (PNCs) have the advantages of naked-eye colorimetric readouts, short response time and noninvasive detection of diabetes, showing immense potential in CGM systems. However, the developed PNCs cannot disperse in physiological environment at the pH of 7.4 because of their poor hydrophilicity. In this study, we report a new kind of PNCs that can continuously and reversibly detect the concentration of glucose (Cg) in physiological environment at the pH of 7.4. Polyacrylic acid (PAA) added to the preparation of PNCs forms hydrogen bonds with polyvinylpyrrolidone (PVP) in Fe3O4@PVP colloidal nanoparticles and the hydrophilic monomer N-2-hydroxyethyl acrylamide (HEAAm), which increases the content of PHEAAm in the polymer shell of prepared PNCs. Moreover, 4-(2-acrylamidoethylcarbamoyl)-3-fluorophenylboronic acid (AFPBA), with a relatively low pKa value, is used as the glucose-sensing monomer to further improve the hydrophilicity and glucose-sensing performances of PNCs. The obtained Fe3O4@(PVP-PAA)@poly(AFPBA-co-HEAAm) PNCs disperse in artificial serum and change color from yellow-green to red when Cg increases from 3.9 mM to 11.4 mM, showing application potential for straightforward CGM.

Synthesis and Characterization of Boronate Affinity Three-Dimensionally Ordered Macroporous Materials

Sample pretreatment is a key step for qualitative and quantitative analysis of trace substances in complex samples. Cis-dihydroxyl (cis-diol) group-containing substances exist widely in biological samples and can be selectively bound by boronate affinity adsorbents. Based on this, in this article, we proposed a simple method for the preparation of novel spherical three-dimensionally ordered macropore (3DOM) materials based on a combination of the boronate affinity technique and colloidal crystal template method. The prepared 3DOM materials were characterized using Fourier transform-infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and thermo-gravimetric analysis, and results showed that they possessed the characteristics of a high specific surface area, high porosity, and more boronic acid recognition sites. The adsorption performance evaluation results showed that the maximum adsorption capacity of the boron affinity 3DOMs on ovalbumin (OVA) could reach to 438.79 mg/g. Kinetic and isothermal adsorption experiments indicated that the boronate affinity 3DOM material exhibited a high affinity and selectivity towards OVA and adenosine. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the proteins in egg whites was conducted and proved that the glycoprotein in the egg whites could be separated and enriched with a good performance. Therefore, a novel boronate affinity 3DOM material a with highly ordered and interconnected pore structure was prepared and could be applied in the separation and enrichment of molecules with cis-diol groups from complex samples with a good selectivity, efficiency, and high throughput.

Synthesis of Boronate Affinity-Based Oriented Dummy Template-Imprinted Magnetic Nanomaterials for Rapid and Efficient Solid-Phase Extraction of Ellagic Acid from Food

Ellagic acid (EA) is a natural polyphenol and possesses excellent in vivo bioactivity and antioxidant behaviors, which play an important role in the treatment of oxidative stress-related diseases, such as cancer. Additionally, EA is also known as a skin-whitening ingredient. The content of EA would determine its efficacy. Therefore, the accurate analysis of EA content can provide more information for the scientific consumption of EA-rich foods and cosmetics. Nevertheless, the analysis of EA in these samples is challenging due to the low concentration level and the presence of interfering components with high abundance. Molecularly imprinted polymers are highly efficient pretreatment materials in achieving specific recognition of target molecules. However, the traditional template molecule (EA) could not be absolutely removed. Hence, template leakage continues to occur during the sample preparation process, leading to a lack of accuracy in the quantification of EA in actual samples, particularly for trace analytes. In addition, another drawback of EA as an imprinting template is that EA possesses poor solubility and a high price. Gallic acid (GA), called dummy templates, was employed for the synthesis of MIPs as a solution to these challenges. The approach used in this study was boronate affinity-based oriented surface imprinting. The prepared dummy-imprinted nanoparticles exhibited several significant advantages, such as good specificity, high binding affinity ((4.89 ± 0.46) × 10-5 M), high binding capacity (6.56 ± 0.35 mg/g), fast kinetics (6 min), and low binding pH (pH 5.0) toward EA. The reproducibility of the dummy-imprinted nanoparticles was satisfactory. The dummy-imprinted nanoparticles could still be reused even after six adsorption-desorption cycles. In addition, the recoveries of the proposed method for EA at three spiked levels of analysis in strawberry and pineapple were 91.0-106.8% and 93.8-104.0%, respectively, which indicated the successful application to real samples.

Imaging the extracellular matrix in live tissues and organisms with a glycan-binding fluorophore

All multicellular systems produce and dynamically regulate extracellular matrices (ECM) that play important roles in both biochemical and mechanical signaling. Though the spatial arrangement of these extracellular assemblies is critical to their biological functions, visualization of ECM structure is challenging, in part because the biomolecules that compose the ECM are difficult to fluorescently label individually and collectively. Here, we present a cell-impermeable small molecule fluorophore, termed Rhobo6, that turns on and red shifts upon reversible binding to glycans. Given that most ECM components are densely glycosylated, the dye enables wash-free visualization of ECM, in systems ranging from in vitro substrates to in vivo mouse mammary tumors. Relative to existing techniques, Rhobo6 provides a broad substrate profile, superior tissue penetration, nonperturbative labeling, and negligible photobleaching. This work establishes a straightforward method for imaging the distribution of ECM in live tissues and organisms, lowering barriers for investigation of extracellular biology.

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.

Homeopathic Formulations of Syzygium jambolanum Alleviate Glycation-Mediated Structural and Functional Modifications of Albumin: Evaluation through Multi-Spectroscopic and Microscopic Approaches

BACKGROUND

 The growing interest in identifying the mode of action of traditional medicines has strengthened its research. Syzygium jambolanum (Syzyg) is commonly prescribed in homeopathy and is a rich source of phytochemicals.

OBJECTIVE

 The present study aims to shed light on the anti-glycation molecular mechanism of Syzyg mother tincture (MT), 30c, and 200c on glycated human serum albumin (HSA) by multi-spectroscopic and microscopic approaches.

METHODS

 The phytochemicals and antioxidant potential of the Syzyg formulations were estimated by the high-performance liquid chromatography and spectroscopic technique, respectively. Glycation was initiated by incubating HSA with methylglyoxal, three Syzyg formulations, and the known inhibitor aminoguanidine in separate tubes at 37°C for 48 hours. The formation of glycation adducts was assessed by spectrofluorometer and affinity chromatography. The structural modifications were analyzed through circular dichroism, Fourier transform infrared spectroscopy, turbidity, 8-anilinonapthalene-1-sulfonic acid fluorescence, and nuclear magnetic resonance. Further, the formation of the aggregates was examined by thioflavin T, native-polyacrylamide gel electrophoresis, and transmission electron microscopy. Additionally, the functional modifications of glycated HSA were determined by esterase-like activity and antioxidant capacity. The binding analysis of Syzyg formulations with glycated HSA was evaluated by surface plasmon resonance (SPR).

RESULTS

 Syzyg formulations MT, 30c, and 200c contained gallic acid and ellagic acid as major phytochemicals, with concentrations of 16.02, 0.86, and 0.52 µg/mL, and 227.35, 1.35, and 0.84 µg/mL, respectively. Additionally, all three formulations had remarkable radical scavenging ability and could significantly inhibit glycation compared with aminoguanidine. Further, Syzyg formulations inhibited albumin's structural and functional modifications. SPR data showed that Syzyg formulations bind to glycated HSA with an equilibrium dissociation constant of 1.10 nM.

CONCLUSION

 Syzyg formulations inhibited the glycation process while maintaining the structural and functional integrity of HSA.

Rational design of nanozyme with integrated sample pretreatment for colorimetric biosensing

Nanozymes have been widely used in the field of biosensing owing to their high stability, low cost, adjustable catalytic activity, and convenient modification. However, achieving high selectivity and sensitivity simultaneously in nanozyme-based colorimetric sensing remains a major challenge. Nanozymes are nanomaterials with enzyme-simulating activity that are often used as solid-phase adsorbents for sample pretreatment. Our design strategy integrated sample pretreatment function into the nanozyme through separation and enrichment, thereby improving the selectivity and sensitivity of nanozyme-based colorimetric biosensing. As a proof-of-concept, glucose was used as the model analyte in this study. A phenylboric acid-modified magnetic nanozyme (Cu/Fe3O4@BA) was rationally designed and synthesized. Selectivity was enhanced by boronate-affinity specific adsorption and the elimination of interference after magnetic separation. In addition, magnetic solid-phase extraction enrichment was used to improve the sensitivity. A recovery rate of more than 80% was reached when the enrichment factor was 50. The synthesized magnetic Cu/Fe3O4@BA was recyclable at least five times. The proposed method exhibited excellent selectivity and sensitivity, simple operation, and recyclability, providing a novel and practical strategy for designing multifunctional nanozymes for biosensing.

Electrospun Fiber Membrane with the Dual Affinity of Chelation and Covalent Interactions for the Efficient Enrichment of Glycoproteins

As important biomarkers of many diseases, glycoproteins are of great significance to biomedical science. It is essential to develop efficient glycoprotein enrichment platforms and investigate their adsorption mechanism. In this work, a conspicuous enrichment strategy for glycoproteins was developed by using an electrospun fiber membrane wrapped with polydopamine (PDA) and modified with 3-aminophenylboronic acid and nickel ions, named PAN/DA@PDA@APBA/Ni. The enrichment characteristics of PAN/DA@PDA@APBA/Ni toward glycoproteins were explored through adsorption behavior. Thanks to the existence of two sites of interaction (metal ion chelation and boronate affinity), PAN/DA@PDA@APBA/Ni exhibited significant enrichment capacity for glycoproteins, ovalbumin (604.6 mg/g), and human immunoglobulin G (331.0 mg/g). The adsorption kinetic results of glycoprotein ovalbumin on PAN/DA@PDA@APBA/Ni conform to the pseudo-first-order kinetic model in the first adsorption stage, while the second half adsorption stage is more in line with the pseudo-second-order kinetic model. Moreover, the physical characteristics of PAN/DA@PDA@APBA/Ni and subsequent adsorption experiments on electrospun fiber modified with only phenylboronic acid or nickel ions both confirmed two sites of interaction (metal ion chelation and boronate affinity, respectively). Furthermore, a stepwise elution method with dual-affinity interaction was designed and successfully applied to enrich glycoproteins in real biological samples. This work provides an idea for sample pretreatment, especially for the design of dual-affinity materials in glycoproteins enrichment.

Phenylboronate-salicylate ester cross-linked self-healing hydrogel composed of modified hyaluronan at physiological pH

Several hydrogels with boronate/diol ester cross-linking have been reported. However, multiple synthetic steps or expensive reagents are required to modify some diol moieties into polymers. Therefore, diol-modified polymers, which are easily and inexpensively prepared via a single-step process, are required for the formation of boronate esters. This study reports a novel hydrogel composed of phenylboronic acid-modified hyaluronic acid and salicylic acid-modified hyaluronic acid. This hydrogel is injectable, can self-heal at physiological pH, and can be easily and inexpensively prepared. The polymer system behaved as a sol at pH 12.0 and a weak gel at pH 9.4 and 11.2, whereas it behaved as a gel over a wide pH range of 4.0-8.2. The viscoelasticity of the system decreased in response to sugar at pH 7.3. Thus, salicylic acid can be considered a promising diol moiety for hydrogel formation via boronate ester cross-linking.

Visualized sensing of erythritol using a simple enzyme-free catechol-based hydrogel film

Based on the versatile properties of bio-derived materials, non-enzymatic assays in combination with electronic devices have attracted increasing interest. Here, we report a novel enzyme-free visualization approach for the detection of erythritol, which is a zero-calorie natural sweetener and serves as an ideal sucrose substitute for diabetics or overweight people who need sugar control. The recognition element of the electrochemical biosensor was constructed by catechol modification on a chitosan-based hydrogel film. The signal transduction was achieved by the competitive binding assay of sweeteners. The results show that 2-fluorophenylboronic acid (FPBA) can form a cyclic boronate ester with the ortho-hydroxyls of both reduced catechol and oxidized quinone, impeding the electron transfer and leading to redox signal attenuation. The addition of sweeteners caused a competitive reaction resulting in bonding between the 1,2-diols and FPBA moieties, and in the recovery of the redox signals. Importantly, the pattern of redox signal changes of catechol can be detected optically, as the oxidized quinone state is darker in color than the reduced catechol state. Using a simple cell phone imaging application, we demonstrate that erythritol can be distinguished from other sweeteners in real samples using the oxidized catechol-Chit0/agarose hydrogel film. Thus, we envision that this method could allow diabetics and people who need to control their sugar intake to detect whether the product contains only erythritol in the field or at home. In addition, this work further illustrates the potential of bio-derived materials for performing redox-based functions and enzyme-free visualization assays.

The Rise of Boron-Containing Compounds: Advancements in Synthesis, Medicinal Chemistry, and Emerging Pharmacology

Boron-containing compounds (BCC) have emerged as important pharmacophores. To date, five BCC drugs (including boronic acids and boroles) have been approved by the FDA for the treatment of cancer, infections, and atopic dermatitis, while some natural BCC are included in dietary supplements. Boron's Lewis acidity facilitates a mechanism of action via formation of reversible covalent bonds within the active site of target proteins. Boron has also been employed in the development of fluorophores, such as BODIPY for imaging, and in carboranes that are potential neutron capture therapy agents as well as novel agents in diagnostics and therapy. The utility of natural and synthetic BCC has become multifaceted, and the breadth of their applications continues to expand. This review covers the many uses and targets of boron in medicinal chemistry.

Chemo-Selective Single-Cell Metabolomics Reveals the Spatiotemporal Behavior of Exogenous Pollutants During Xenopus Laevis Embryogenesis

In-depth profiling of embryogenesis-associated endogenous and exogenous metabolic changes can reveal potential bio-effects resulting from human-made chemicals and underlying mechanisms. Due to the lack of potent tools for monitoring spatiotemporal distribution and bio-transformation behavior of dynamic metabolites at single-cell resolution, however, how and to what extent environmental chemicals may influence or interfere embryogenesis largely remain unclear. Herein, a zero-sample-loss micro-biopsy-based mass spectrometric platform is presented for quantitative, chemo-selective, high-coverage, and minimal-destructive profiling of development-associated cis-diol metabolites, which are critical for signal transduction and epigenome regulation, at both cellular level and tissue level of Xenopus laevis. Using this platform, three extraordinary findings that are otherwise hard to achieve are revealed: 1) there are characteristically different cis-diol metabolic signatures among oocytes, anterior and posterior part of tailbud-stage embryos; 2) halogenated cis-diols heavily accumulate at the posterior part of tailbud-stage embryos of Xenopus laevis; 3) dimethachlon, a kind of exogenous fungicide that is widely used as pesticide, may be bio-transformed and accumulated in vertebrate animals in environment. Thus, this study opens a new avenue to simultaneously monitoring intercellular and intraembryonic heterogeneity of endogenous and exogenous metabolites, providing new insights into metabolic remolding during embryogenesis and putting a warning on potential environmental risk.

Surface Modification of Polystyrene with Boronic Acid for Immunoaffinity-Based Cell Enrichment

Obtaining an enriched and phenotypically pure cell population from heterogeneous cell mixtures is important for diagnostics and biosensing. Existing techniques such as fluorescent-activated cell sorting (FACS) and magnetic-activated cell sorting (MACS) require preincubation with antibodies (Ab) and specialized equipment. Cell immunopanning removes the need for preincubation and can be done with no specialized equipment. The majority of the available antibody-mediated analyte capture techniques require a modification to the Abs for binding. In this work, no antibody modification is used because we take advantage of the carbohydrate chain in the Fc region of Ab. We use boronic acid as a cross-linker to bind the Ab to a modified surface. The process allows for functional orientation and cleavable binding of the Ab. In this study, we created an immunoaffinity matrix on polystyrene (PS), an inexpensive and ubiquitous plastic. We observed a 37% increase in Ab binding compared with that of a passive adsorption approach. The method also displayed a more consistent antibody binding with 17 times less variation in Ab loading among replicates than did the passive adsorption approach. Surface topography analysis revealed that a dextran coating reduced nonspecific antibody binding. Elemental analysis (XPS) was used to characterize the surface at different stages and showed that APBA molecules can bind upside-down on the surface. While upside-down antibodies likely remain functional, their elution behavior might differ from those bound in the desired way. Cell capture experiments show that the new surface has 43% better selectivity and 2.4-fold higher capture efficiency compared to a control surface of passively adsorbed Abs. This specific surface chemistry modification will allow the targeted capture of cells or analytes with the option of chemical detachment for further research and characterization.

Quantification of Plasma Dopamine in Depressed Patients Using Silver-Enriched Silicon Nanowires as SERS-Active Substrates

A decrease in the levels of dopamine (DA)─a key catecholamine biomarker for major depressive disorder─highlights the need for quantitative analysis of biological fluids to aid in the early diagnosis of diverse neuropsychiatric disorders. This study developed silicon nanowires enriched with silver nanoparticles to serve as a surface-enhanced Raman scattering (SERS) substrate to enable precise and sensitive quantification of blood plasma DA levels in humans. The silver-enriched silicon nanowires (SiNWs@Ag) yielded flower-like assemblies with densely populated SERS "hot spots," allowing sensitive DA detection. By correlating DA concentration with Raman intensity at 1156 cm-1, the plasma DA levels in treatment-naïve patients with major depression (n = 18) were 2 orders of magnitude lower than those in healthy controls (n = 18) (6.56 × 10-10 M vs 1.43 × 10-8 M). The plasma DA concentrations differed significantly between the two groups (two-tailed p = 5.77×10-7), highlighting a distinct demarcation between depression patients and healthy controls. Furthermore, the SiNWs@Ag substrate effectively differentiated between DA and norepinephrine (NE) in mixtures at nanomolar levels, demonstrating its selective detection capability. This study represents the first report on the quantitative detection of DA levels in human blood samples from individuals with major depression using an SERS technique, emphasizing its potential clinical utility in the evaluation and diagnosis of neuropsychiatric disorders.

Glycan-specific molecularly imprinted polymers towards cancer diagnostics: merits, applications, and future perspectives

Aberrant glycans are a hallmark of cancer states. Notably, emerging evidence has demonstrated that the diagnosis of cancers with tumour-specific glycan patterns holds great potential to address unmet medical needs, especially in improving diagnostic sensitivity and selectivity. However, despite vast glycans having been identified as potent markers, glycan-based diagnostic methods remain largely limited in clinical practice. There are several reasons that prevent them from reaching the market, and the lack of anti-glycan antibodies is one of the most challenging hurdles. With the increasing need for accelerating the translational process, numerous efforts have been made to find antibody alternatives, such as lectins, boronic acids and aptamers. However, issues concerning affinity, selectivity, stability and versatility are yet to be fully addressed. Molecularly imprinted polymers (MIPs), synthetic antibody mimics with tailored cavities for target molecules, hold the potential to revolutionize this dismal progress. MIPs can bind a wide range of glycan markers, even those without specific antibodies. This capacity effectively broadens the clinical applicability of glycan-based diagnostics. Additionally, glycoform-resolved diagnosis can also be achieved through customization of MIPs, allowing for more precise diagnostic applications. In this review, we intent to introduce the current status of glycans as potential biomarkers and critically evaluate the challenges that hinder the development of in vitro diagnostic assays, with a particular focus on glycan-specific recognition entities. Moreover, we highlight the key role of MIPs in this area and provide examples of their successful use. Finally, we conclude the review with the remaining challenges, future outlook, and emerging opportunities.

Magnetic dendritic mesoporous silica nanoparticles based integrated platform for rapid and efficient analysis of saccharides

BACKGROUND

As an essential compound in living organism, saccharides have attracted enormous attentions from scientists in various fields. Understanding the distribution of saccharides in various samples is of great scientific importance. However, the low signal response and lack of specific recognition technology of saccharides and the complex matrix of samples make the analysis of saccharides a very challenge task. Thus, the development of a simple and straightforward strategy for the analysis of saccharides would represent a great contribution to the field.

RESULTS

In this study, by employing the sulfonyl functionalized magnetic dendritic mesoporous silica nanoparticles as the substrate, we develop an integrated platform for analysis of saccharides. The construction of the platform mainly relied on multi-functional boronic acid, which serves as separation and derivation ligands at the same time. In the general procedure, the boronic acid is first immobilized onto the surface of substrate, then the selective enrichment of saccharides can be realized via boronate affinity separation. Finally, by the rational choice of the solution, we are able to elute the labelled complex (boronic acid-saccharide) from the substrate, which can be direct subjected to HPLC-UV analysis. The reliable precision (<15 %), accuracy (80-100 %), reproducibility (<10 %), improved sensitivity (20x) and limited time-consuming (down to minutes) of the proposed platform are experimentally demonstrated.

SIGNIFICANCE AND NOVELTY

The successful quantification of different saccharides (alditols, glucose) in real samples is achieved. The proposed strategy is not only straightforward and fast, but also avoid the requirement of special equipment. With these attractive features, we believe that this strategy will greatly prompt the analysis of saccharides in various samples (eg. food, pharmaceutics and biosamples).

Arylazo sulfones: multifaceted photochemical reagents and beyond

The photochemical action of arylazo sulfones under visible light irradiation has recently gained considerable attention for the construction of carbon-carbon and carbon-heteroatom bonds in organic synthesis. The inherent dyedauxiliary group (-N2SO2R) embedded in the reagent is responsible for the absorption of visible light even in the absence of a photocatalyst, additive or oxidant, leading to the generation of three different radicals, viz. aryl (carbon-centred), sulfonyl (sulphur-centred) and diazenyl (nitrogen-centred) radicals, under different reaction conditions. Encountering a reagent with such a versatile behaviour is quite rare, which makes arylazo sulfones a highly interesting class of compounds. The mild reaction conditions under which these reagents can operate are an added advantage. Recently, they are also being used as non-ionic photoacid generators (PAGs), electron acceptors, and hydrogen atom transfer (HAT) and imination reagents in a number of synthetic transformations. They have displayed substantial damaging effect on the structure of DNA in the presence of light which can lead to their use as phototoxic pharmaceuticals for cancer treatment. Moreover, their photochemistry is also being exploited in polymerization reactions (as photoinitiators) and in materials chemistry (surface modification).

Boronic Acid-Decorated Carbon Dot-Based Semiselective Multichannel Sensor Array for Cytokine Discrimination and Oral Cancer Diagnosis

Cytokines are essential components of the immune system and are recognized as significant biomarkers. However, detection of a single cytokine is not precise and reliable enough to satisfy the requirements for diagnosis. Herein, we developed a pattern recognition-based method for the multiplexed sensing of cytokines, which involves three-color-emitting boronic acid-decorated carbon dots (BCDs) and arginine-modified titanium carbide (Ti3C2 MXenes) as the sensor array. Initially, the fluorescence signals of the three BCDs were quenched by Ti3C2 MXenes. In the presence of cytokines, the fluorescence intensity of the BCDs was restored or further quenched by different cytokines. The fluorescence response occurs in two steps: first, boronic acid interacts with cis-diol functional groups of cytokines, and second, arginine headgroup selectively interacts with glycans. By exploiting the different competing binding of the BCDs and the cytokines toward Ti3C2 MXenes, seven cytokines and their mixtures can be effectively discriminated at a concentration of 20 ng mL-1. Furthermore, our sensor array demonstrated an excellent performance in classifying human oral cancer saliva samples from healthy individuals with clinically relevant specificity. The noninvasive method offers a rapid approach to cytokine analysis, benefiting early and timely clinical diagnosis and treatment.

Enrichment of sialic acid-containing casein glycomacropeptide in protein hydrolysates using phenylboronic acid-functionalized mesoporous silica nanoparticles

Glycomacropeptide (GMP) is a bioactive peptide of high value, rich in glycosylation sites and with physiological and dietary therapeutic value. The enrichment and detection of GMP facilitates the accurate quantification and the identification of adulteration of GMP in food products. In GMP, sialic acid is an abundant glycosyl group and is mainly located at the end of the sugar chain. Here, we propose a novel GMP enrichment strategy based on the affinity of sialic acid for phenylboronic acid groups that shift with environmental pH. As an enrichment material, mesoporous silica nanoparticles were progressively modified with aminopropyl and phenylboronic acid groups. The developed material showed excellent selectivity for sialic acid in the presence of galactose and fucose as interferents. The adsorption behavior of sialic acid-containing GMP fits the Langmuir adsorption model, offering a recovery of 71.72% (in terms of sialic acid content) and a GMP relative purity of 0.957. Results from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and size exclusion chromatography confirm that the enriched GMP contains almost no other unexpected proteins and peptides, indicating that the developed strategy holds promise for purifying GMP in various dairy systems.

Highly efficient determination of trace ascorbic acid in vitamin C tablets by boronate affinity-modified magnetic metal-organic frameworks

Ascorbic acid (AA) plays an important role in many life processes. The chronic nutritional deficiency of AA will lead to the symptoms of scurvy. Therefore, the sensitive quantitative detection of AA is most important in the pharmaceutical analysis, food industry and diagnostic application. In this study, a dual-functional magnetic metal-organic frameworks (Fe3O4@SiO2@UiO-PBA) nanoparticles was synthesized by modifying phenylboronic acid to the surface of magnetic UiO-66-NH2 via postsynthetic modification for selectively and sensitively florescent detection of AA. Due to the abundant amino groups and grafted phenylboronic acid, the proposed nanoparticles have the dual properties of hydrophilicity and boronate affinity. Under optimum conditions, the obtained Fe3O4@SiO2@UiO-PBA nanoparticles can detect AA within 30 s, and has a good linear relationship with the concentration of AA in the range of 5.0-60 μM with a detection limit of 2.5 μM (S/N = 3). In addition, the prepared Fe3O4@SiO2@UiO-PBA nanoparticles showed excellent selectivity and great potential application in the highly efficient determination of trace AA in vitamin C tablets. These results indicated that a convenient method was proposed to develop fluorescent probes for rapid and sensitive detection of trace AA in real samples.

Highly efficient production and simultaneous purification of d-tagatose through one-pot extraction-assisted isomerization of d-galactose

A one-pot extraction-assisted d-galactose-to-d-tagatose isomerization strategy was proposed based on the selective extraction of d-tagatose by phenylborate anions. 4-Vinylphenylboronic acid was selected with high extraction efficiency and selectivity towards d-tagatose. The extracted sugars could be desorbed through a two-staged stripping process with the purity of d-tagatose significantly increased. In-situ extraction-assisted d-galactose-to-d-tagatose isomerization was implemented for the first time ever reported, and the effect of boron-to-sugar ratio (boron: sugar) was investigated. The conversion yield of d-tagatose at 60 °C increased from ∼ 39 % (boron: sugar = 0.5) to ∼ 56 % (boron: sugar = 1) but then decreased to ∼ 44 % (boron: sugar = 1.5). With temperature increased to 70 °C, the conversion yield of d-tagatose was further improved to ∼ 61 % (boron: sugar = 1.5), with the minimized formation of byproducts. Moreover, high purity (∼83 %) and concentrated d-tagatose solution (∼40 g/L) was obtained after sequential desorption. The proposed extraction-assisted isomerization strategy achieved improving the yield and purity of d-tagatose, proving its feasibility in industrial applications.

Comprehensive Overview the Role of Glycosylation of Extracellular Vesicles in Cancers

Extracellular vesicles (EVs) are membranous structures secreted by various cells carrying diverse biomolecules. Recent advancements in EV glycosylation research have underscored their crucial role in cancer. This review provides a global overview of EV glycosylation research, covering aspects such as specialized techniques for isolating and characterizing EV glycosylation, advances on how glycosylation affects the biogenesis and uptake of EVs, and the involvement of EV glycosylation in intracellular protein expression, cellular metastasis, intercellular interactions, and potential applications in immunotherapy. Furthermore, through an extensive literature review, we explore recent advances in EV glycosylation research in the context of cancer, with a focus on lung, colorectal, liver, pancreatic, breast, ovarian, prostate, and melanoma cancers. The primary objective of this review is to provide a comprehensive update for researchers, whether they are seasoned experts in the field of EVs or newcomers, aiding them in exploring new avenues and gaining a deeper understanding of EV glycosylation mechanisms. This heightened comprehension not only enhances researchers' knowledge of the pathogenic mechanisms of EV glycosylation but also paves the way for innovative cancer diagnostic and therapeutic strategies.

Production of high-purity lactulose via an integrated one-pot boronate affinity adsorbent based adsorption-assisted isomerization and simultaneous purification

High-purity lactulose is mandatory for its medical uses and food applications. This work developed an efficient lab-scale strategy for the synthesis of high-purity lactulose by combining lactose-to-lactulose isomerization with simultaneous recovery of lactulose, which was conducted concurrently and semi-continuously in a boronate affinity adsorbent-packed column. The first step covers the boronate affinity adsorbent-based adsorption-assisted lactose-to-lactulose isomerization. Under optimized conditions, in situ selectively binding of the newly formed lactulose onto the boronate affinity adsorbent enables a much-enhanced lactulose yield up to 80.20% with the lowest byproducts yield of 6.30%. Afterward, over 90% of the adsorbed lactulose can be recovered through sequential desorption with purity >98%. The net outcome of the applied strategy was the yield of high-purity lactulose up to 72.31%, the highest value ever reported. Moreover, the packed column displayed excellent operational stability. The encouraging results validate the high potential of this approach in the sustainable production of high-purity lactulose.

Simultaneous Mapping of Amino Neurotransmitters and Nucleoside Neuromodulators on Brain Tissue Sections by On-Tissue Chemoselective Derivatization and MALDI-MSI

Neurotransmitters (NTs) and neuromodulators (NMs) are two of the most important neurochemicals in the brain, and their imbalances in specific brain regions are thought to underlie certain neurological disorders. We present an on-tissue chemoselective derivatization mass spectrometry imaging (OTCD-MSI) method for the simultaneous mapping of NTs and NMs. Our derivatization system consists of a pyridiniumyl-benzylboronic acid based derivatization reagent and pyrylium salt, which facilitate covalent charge labeling of molecules containing cis-diol and primary amino, respectively. These derivatization systems improved the detection sensitivity of matrix-assisted laser desorption/ionization (MALDI)-MSI and simplified the identification of amino NTs and nucleoside NMs by the innate chemoselectivity of derivatization reagents and the unique isotopic pattern of boron-derivative reagents. We demonstrated the ability of the developed method on brain sections from a hypoxia mouse model and control. The simultaneous imaging of NTs and NMs provided a method for exploring how hypoxic stress and drugs affect specific brain regions through neurotransmitter modulation.

Discrimination of cis-diol-containing molecules using fluorescent boronate affinity probes by principal component analysis

Fluorescent boronate affinity molecules have gained increasing attention in the field of fluorescence sensing and detection due to their selective recognition capability towards cis-diol-containing molecules (cis-diols). However, the conventional fluorescent boronate affinity molecules face a challenge in differentiating the type of cis-diol only by their fluorescence responses. In this study, a simple method was used to discriminate different types of cis-diols, including nucleosides, nucleotides, sugars, and glycoproteins based on the phenylboronic acid-functionalized fluorescent molecules combined with principal component analysis (PCA). Both fluorescent molecules were simply synthesized by the covalent interaction between the amino group in 3-aminophenyl boronic acid and the isothiocyanate group in fluorescein or rhodamine B. In view of their fluorescence-responsive behaviors to these cis-diols directly, it is impossible to differentiate their types even under the optimized experimental conditions. When PCA was employed to treat the fluorescence response data and the quenching constants with their molecular weight, different types of cis-diols can be distinguished successfully. As a result, by integrating the fluorescence response of the boronate affinity probes with PCA, it can greatly improve the specific recognition capability of the boronic acids, providing a simple and direct way to distinguish and identify different types of cis-diols.

Platelet Rich Plasma Loaded Multifunctional Hydrogel Accelerates Diabetic Wound Healing via Regulating the Continuously Abnormal Microenvironments

Continuous oxidative stress and cellular dysfunction caused by hyperglycemia are distinguishing features of diabetic wounds. It has been a great challenge to develop a smart dressing that can accelerate diabetic wound healing through regulating abnormal microenvironments. In this study, a platelet rich plasma (PRP) loaded multifunctional hydrogel with reactive oxygen species (ROS) and glucose dual-responsive property is reported. It can be conveniently prepared with PRP, dopamine (DA) grafted alginate (Alg-DA), and 6-aminobenzo[c][1,2]oxaborol-1(3H)-ol (ABO) conjugated hyaluronic acid (HA-ABO) through ionic crosslinks, hydrogen-bond interactions, and boronate ester bonds. The hydrogel possesses injectability, moldability, tissue adhesion, self-healing, low hemolysis, and hemostasis performances. Its excellent antioxidant property can create a low oxidative stress microenvironment for other biological events. Under an oxidative stress and/or hyperglycemia state, the hydrogel can degrade at an accelerated rate to release a variety of cytokines derived from activated blood platelets. The result is a series of positive changes that are favorable for diabetic wound healing, including fast anti-inflammation, activated macrophage polarization toward M2 phenotype, promoted migration and proliferation of fibroblasts, as well as expedited angiogenesis. This work provides an efficient strategy for chronic diabetic wound management and offers an alternative for developing a new-type PRP-based bioactive wound dressing.

A reactive matrix for in situ chemical derivatisation and specific detection of cis-diol compounds by matrix-assisted laser desorption/ionisation mass spectrometry

Analysis of cis-diol compounds is essential, because they play important roles in cosmetics, food, pharmaceuticals, and living organisms. Herein, we describe the development of a matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS) method to analyse cis-diol compounds. In this method, a 6-borono-1-methylquinoline-1-ium (BMQI) reactive matrix was designed for in situ derivatisation of cis-diol compounds based on the boronate affinity interaction between boronic acid and cis-diol groups. Compared to traditional commercial matrices and other boronic acid reagents, BMQI can significantly accelerate the desorption/ionisation process, improve reproducibility, exhibit free background interference, and enhance signal intensity in the analysis of various cis-diol compounds even for amounts as low as 1 nmol. The BMQI-assisted laser desorption/ionisation mass spectrometry (LDI-MS) was successfully applied to the rapid screening and identification of sugar alcohols in different sugar-free foods. This work provides an alternative method to the LDI-MS analysis of cis-diol-containing molecules, and the method can be extended to other food samples and biofluids.

Amplification-Free Ratiometric Electrochemical Aptasensor for Point-of-Care Detection of Therapeutic Monoclonal Antibodies

The rapid quantification of therapeutic monoclonal antibodies (mAbs) is of great significance to their pharmacokinetics/pharmacodynamics (PK/PD) research and the personalized medication for disease treatment. Taking advantage of the direct decoration of tens of redox tags to the target of interest, we illustrate herein an amplification-free ratiometric electrochemical aptasensor for the point-of-care (POC) detection of trace amounts of therapeutic mAbs. The POC detection of therapeutic mAbs involved the use of the methylene blue (MB)-conjugated aptamer as the affinity element and the decoration of therapeutic mAbs with ferrocene (Fc) tags via the boronate crosslinking, in which the MB-derived peak current was used as the reference signal, and the peak current of the Fc tag was used as the output signal. As each therapeutic mAb carries tens of diol sites for the site-specific decoration of the Fc output tags, the boronate crosslinking enabled the amplification-free detection, which is cost-effective and quite simple in operation. In the presence of bevacizumab (BevMab) as the target, the resulting ratiometric signal (i.e., the IFc/IMB value) exhibited a good linear response over the range of 0.025-2.5 μg/mL, and the limit of detection (LOD) of the electrochemical aptasensor was 6.5 ng/mL. Results indicated that the aptamer-based affinity recognition endowed the detection of therapeutic mAbs with high selectivity, while the ratiometric readout exhibited satisfactory reproducibility and robustness. Moreover, the ratiometric electrochemical aptasensor is applicable to the detection of therapeutic mAbs in serum samples. Taking together, the amplification-free ratiometric electrochemical aptasensor holds great promise in the POC detection of therapeutic mAbs.

Benzoxaborole-grafted high molecular weight chitosan from prawn: Synthesis, characterization, target recognition and antibacterial properties

Boronated polymers are in the focus of dynamic functional materials due to the versatility of the B-O interactions and accessibility of precursors. Polysaccharides are highly biocompatible, and therefore, an attractive platform for anchoring boronic acid groups for further bioconjugation of cis-diol containing molecules. We report for the first time the introduction of benzoxaborole by amidation of the amino groups of chitosan improving solubility and introducing cis-diol recognition at physiological pH. The chemical structures and physical properties of the novel chitosan-benzoxaborole (CS-Bx) as well as two phenylboronic derivatives synthesized for comparison, were characterized by nuclear magnetic resonance (NMR), infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic light scattering (DLS), rheology and optical spectroscopic methods. The novel benzoxaborole grafted chitosan was perfectly solubilized in an aqueous buffer at physiological pH, extending the possibilities of boronated materials derived from polysaccharides. The dynamic covalent interaction between boronated chitosan and model affinity ligands, was studied by means of spectroscopy methods. A glycopolymer derived from poly(isobutylene-alt-anhydride) was also synthesized to study the formation of dynamic assemblies with benzoxaborole-grafted chitosan. A first approximation to apply fluorescence microscale thermophoresis for the interactions of the modified polysaccharide is also discussed. Additionally, the activity of CSBx against bacterial adhesion was studied.

Electrochemical detection of glycoproteins using boronic acid-modified metal-organic frameworks as dual-functional signal reporters

The sensitive analysis of glycoproteins is of great importance for early diagnosis and prognosis of diseases. In this work, a sandwich-type electrochemical aptasensor was developed for the detection of glycoproteins using 4-formylphenylboric acid (FPBA)-modified Cu-based metal-organic frameworks (FPBA-Cu-MOFs) as dual-functional signal probes. The target captured by the aptamer-modified electrode allowed the attachment of FPBA-Cu-MOFs based on the interaction between boronic acid and glycan on glycoproteins. Large numbers of Cu2+ ions in FPBA-Cu-MOFs produced an amplified signal for the direct voltammetric detection of glycoproteins. The electrochemical aptasensor showed a detection limit as low as 6.5 pg mL-1 for prostate specific antigen detection. The method obviates the use of antibody and enzymes for molecular recognition and signal output. The dual-functional MOFs can be extended to the design of other biosensors for the determination of diol-containing biomolecules in clinical diagnosis.

Review of recent advances in development and applications of organic-silica hybrid monoliths

Organic-silica hybrid monoliths attracted attention as an alternative to extensively researched organic polymer-based and silica-based counterparts. The development and applications of these materials as extraction and separation media in capillary liquid chromatography and capillary electrochromatography were previously reviewed in several manuscripts. In this review, we will concentrate on work published since mid-2016 focusing on advances in their development using sol-gel chemistry of tetra- and trialkoxysilanes and subsequent surface modification with organic monomers, and "one-pot" strategy incorporating sol-gel chemistry of alkoxysilanes and free-radical polymerization, ring-opening polymerization, or thiol-based click polymerization with organic monomers. Approaches adapted to the preparation of hybrid monoliths made with polyhedral oligomeric silsesquioxanes will be covered as well.

Combining multisite functionalized magnetic nanomaterials with interference-free SERS nanotags for multi-target sepsis biomarker detection

Surface-enhanced Raman scattering (SERS) is an ultra-sensitive vibration spectroscopy technology, with the advantages of multi-index and non-destructive quantitative detection, has attracted much attention in the joint detection of biomarkers. A novel SERS biosensor with multisite capture and interference-free quantification was designed for the joint detection of the sepsis biomarker interleukin-6 (IL-6) and procalcitonin (PCT). This biosensor had two interference-free core-shell SERS probes with highly efficient electromagnetic enhancement and a multisite functionalized magnetic nanomaterial with high adsorption capacity. They formed sandwich structure with the targets through boronic affinity and immunoreaction, and the multi-target quantitative analysis of biomarkers in serum was performed using a portable Raman spectrometer in the Raman-silent region. The SERS biosensor was exhibited highly sensitive with detection limits of 0.584 and 2.99 pg/mL for IL-6 and PCT, respectively. In addition, it exhibited excellent selectivity and specificity even with the interference of other proteins. As this SERS method showed excellent performance in the detection of sepsis, it has great potential for multi-index detection in clinical diagnosis of major diseases.

pH-responsive magnetic graphene oxide composite as an adsorbent with high affinity for rapid capture of nucleosides

A novel pH-responsive magnetic graphene oxide composite (MGO@PEI-BA) is proposed for the first time as an adsorbent for the rapid capture and detection of nucleosides (cytidine, uridine, guanosine, and adenosine). The morphology, structure, and magnetic properties of the composite were evaluated using various characterization techniques. The results indicated that the composite was successfully fabricated. A series of parameters that affect extraction and elution were optimized through one-factor-at-a-time and Box-Behnken design of response surface methodology (BBD-RSM). The unique layered structures and easily accessible active sites of the composite facilitated molecular transport, resulting in instantaneous equilibrium of nucleosides adsorption within 5 min. Based on this study, a magnetic dispersive micro-solid-phase extraction (MD-μ-SPE) method assisted by the MGO@PEI-BA was developed in combination with UHPLC-UV analysis for the determination of nucleosides in rat urine. Under the optimum conditions, a wide linear range (10-2000 ng mL-1), good linearity (r > 0.99), low detection limits (1-3 ng mL-1), low relative standard deviations (RSDs ≤ 3.9%), and satisfactory recoveries (82.7-96.3%) were achieved. These results demonstrate that the MGO@PEI-BA is an excellent adsorbent for extracting nucleosides from biological samples.

Programmable supramolecular chirality in non-equilibrium systems affording a multistate chiroptical switch

The dynamic regulation of supramolecular chirality in non-equilibrium systems can provide valuable insights into molecular self-assembly in living systems. Herein, we demonstrate the use of chemical fuels for regulating self-assembly pathway, which thereby controls the supramolecular chirality of assembly in non-equilibrium systems. Depending on the nature of different fuel acids, the system shows pathway-dependent non-equilibrium self-assembly, resulting in either dynamic self-assembly with transient supramolecular chirality or kinetically trapped self-assembly with inverse supramolecular chirality. More importantly, successive conducting of chemical-fueled process and thermal annealing process allows for the sequential programmability of the supramolecular chirality between four different chiral hydrogels, affording a new example of a multistate supramolecular chiroptical switch that can be recycled multiple times. The current finding sheds new light on the design of future supramolecular chiral materials, offering access to alternative self-assembly pathways and kinetically controlled non-equilibrium states.

Biosensors with Boronic Acid-Based Materials as the Recognition Elements and Signal Labels

It is of great importance to have sensitive and accurate detection of cis-diol-containing biologically related substances because of their important functions in the research fields of metabolomics, glycomics, and proteomics. Boronic acids can specifically and reversibly interact with 1,2- or 1,3-diols to form five or six cyclic esters. Based on this unique property, boronic acid-based materials have been used as synthetic receptors for the specific recognition and detection of cis-diol-containing species. This review critically summarizes the recent advances with boronic acid-based materials as recognition elements and signal labels for the detection of cis-diol-containing biological species, including ribonucleic acids, glycans, glycoproteins, bacteria, exosomes, and tumor cells. We also address the challenges and future perspectives for developing versatile boronic acid-based materials with various promising applications.

Streptavidin-Conjugated DNA for the Boronate Affinity-Based Detection of Poly(ADP-Ribose) Polymerase-1 with Improved Sensitivity

This work reports the development of a fluorescence method for the detection of poly(ADP-ribose) polymerase-1 (PARP1), in which a phenylboronic acid-modified fluorescein isothiocyanate dye (FITC-PBA) was used to recognize the formed poly(ADP-ribose) (PAR) polymer. The detection system was designed by conjugating recombinant streptavidin (rSA) with PARP1-specific double-stranded DNA (dsDNA) through streptavidin-biotin interaction. Capture of PARP1 via rSA-biotin-dsDNA allowed for the poly-ADP-ribosylation (PARylation) of both rSA and PARP1 in a homogeneous solution. The resulting rSA-biotin-dsDNA/PAR conjugates were then captured and separated via the commercialized nitrilotriacetic acid-nickel ion-modified magnetic bead (MB-NTA-Ni) through the interaction between NTA-Ni on MB surface and oligohistidine (His₆) tag in rSA. The PAR polymer could capture the dye of FITC-PBA through the borate ester interaction between the boronic acid moiety in PBA and the cis-diol group in ribose, thus causing a decrease in fluorescence signal. The PARylation of streptavidin and the influence of steric hindrance on PARylation efficiency were confirmed using reasonable detection strategies. The method showed a wide linear range (0.01~20 U) and a low detection limit (0.01 U). This work should be valuable for the development of novel biosensors for the detection of poly(ADP-ribose) polymerases and diol-containing species.

A universal boronate affinity capture-antibody-independent lateral flow immunoassay for point-of-care glycoprotein detection

Protein glycosylation and other post-translational modifications are involved in many biological processes including growth, development and immune responses, and glycoproteins are also known as biomarkers for cancer, diabetes and cardiovascular diseases. In traditional lateral flow immunoassay (LFIA) for glycoprotein detection, capture antibody (CA) is often required to label targets. However, the production of CA is complicated and expensive, restricting the wide application of LFIA. In this study, we developed a universal boronate affinity CA-independent LFIA method for glycoprotein detection. 4-Mercaptophenylboronic acid (4-MPBA)-modified Au nanoparticles (namely 4-MPBA-AuNPs) were used as LFIA labels, which could generate colorimetric signal and showed outstanding capability to bind glycoprotein. Compared with CA, 4-MPBA molecular as a glycoprotein recognition element had more prominent advantages, e.g., low cost, easy availability and good quality controllability. Take carcinoembryonic antigen (CEA) as model glycoprotein, the limit of detection of this CA-independent LFIA was 1.25 ng/mL by naked eyes, which was 8-fold lower than conventional CA-dependent sandwich LFIA. Significantly, the developed 4-MPBA-AuNPs-based CA-independent LFIA successfully detected 23 CEA-positive samples from 64 suspected human serum samples within 50 min in a nonlaboratory environment, with a 100% accuracy compared to clinical detection method. Therefore, this diagnostic platform could provide an effective tool for point-of-care glycoprotein detection with excellent reproducibility and high specificity.

Highly-tumor-targeted PAD4 inhibitors with PBA modification inhibit tumors in vivo by specifically inhibiting the PAD4-H3cit-NETs pathway in neutrophils

As a new target for tumor therapy, PAD4 protein, shows excellent antitumor activity, and phenylboronic acid (PBA) could combine with sialic acid on the tumor surface to achieve dual targeting in situ and for metastatic tumors. The purpose of this study was therefore to modify PAD4 protein inhibitors with different phenylboronic acid groups in order to obtain highly-targeted PAD4 inhibitors. The activity and mechanism of these PBA-PAD4 inhibitors were studied in vitro by MTT assay, laser confocal analysis, and flow cytometry. The effects of the compounds on primary tumor and lung metastasis in mice were evaluated in vivo using a S180 sarcoma model and a 4T1 breast cancer model. In addition, cytometry mass (CyTOF) was used to analyze the immune microenvironment, and the results show that the PAD4 inhibitor 5i modified by m-PBA at the carboxyl terminal of ornithine skeleton had the best antitumor activity. In vitro evaluation of this activity revealed that 5i could not directly kill tumor cells but had a significant inhibitory effect on tumor cell metastasis. Further mechanism studies showed that 5i could be taken up by 4T1 cells in a time-dependent manner and distributed around the cell membrane but could not be taken up by normal cells. In addition, although 5i was distributed in the cytoplasm of tumor cells while in the nucleus of neutrophils, it could both decrease the histone 3 citrullination (H3cit) in the nucleus. In vivo 4T1 tumor-bearing mouse models, 5i inhibited breast cancer growth and metastasis in a concentration-dependent manner, and NET formation in tumor tissues was significantly reduced. In conclusion, PBA-PAD4 inhibitors show high targeting of tumor cells and good safety in vivo. By specifically inhibiting PAD4 protein in the neutrophil nucleus, PBA-PAD4 inhibitors also show excellent antitumor activity toward growth and metastasis in vivo, which provides a new idea for the design of highly-targeted PAD4 inhibitors.

Hierarchical Macroporous Agarose Materials with Polyethyleneimine-Assisted Multiple Boronate Affinity Binding Sites for the Separation of Neomycin

Quantification of neomycin residues in food samples demands an efficient purification platform. Herein, hierarchical macroporous agarose monoliths with multiple boronate affinity sites were established for selective separation of neomycin. The silica core was synthesized by "one-step" Stöber procedures followed by modification with amino group and incorporation of polyethyleneimine. A versatile macroporous agarose monolith was prepared by emulsification strategies and functionalized with epoxy groups. After introducing polyethyleneimine-integrated silica nanoparticles onto the agarose monolith, fluorophenylboronic acids were immobilized. The physical and chemical characteristics of the composite monolith were analyzed systematically. After optimization, neomycin showed high binding ability of 23.69 mg/g, and the binding capacity can be manipulated by changing the pH and adding monosaccharides. The composite monolith was subsequently utilized to purify neomycin from the spiked model aquatic products followed by high-performance liquid chromatography analysis, which revealed a remarkable neomycin purification effect, indicating the great potential in the separation of neomycin from complicated aquatic products.