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

Aggregation-induced emission (AIE) of Au(I)-GSH complexes activated by cationic polymer for sensitive foodborne pathogens detection and inactivation

Aggregation-induced emission (AIE) is a novel signal output method but is limited in pathogen sensing. Herein, a multifunctional biosensor based on the AIE properties of Au(I)-GSH complexes as signal conversion tags was firstly constructed for rapid and sensitive total bacteria. Bacteria were captured by the boronic acid group of MNPs@Au@4-MPBA (MAu@MPBA) through recognition of peptidoglycan on their surface. Simultaneously, cationic polymer Poly (diallyldimethylammonium chloride) (PDDA) were electrostatic absorb on bacteria. After magnetic separation, the remaining PDDA induced Au(I)-GSH complexes aggregation to produce strong red fluorescence, which was linearly with the quantity of bacteria. Under optimized conditions, quantitative detection of bacteria can be achieved within 60 min, with a minimum detection concentration of 18 CFU/mL. Moreover, 90 % bacteria can be effectively inactivated while being detected. This strategy is capable of sensitively detecting and killing foodborne pathogens and can be successfully applied to food safety monitoring.

Rapid analysis of six cytokinins in tomato plants using phenylboronic acid and ionic liquid functionalized monolithic capillary column combined with UHPLC-MS/MS

In this study, 4-vinylphenylboronic acid, ionic liquid, and dipentaerythritolhexakis(3-mercaptopropionate) were used as functional monomers to prepare monolithic column in fused-silica capillaries by thermally induced sulfhydryl-alkenyl click polymerization. Based on the properties of 4-vinylphenylboronic acid and ionic liquid, the monolithic capillary column (VPBA-SH-IL) exhibited excellent permeability and chemical stability with the ability to efficiently enrich trace amounts of cytokinins from complex substrates via B←N coordination, π-π interactions, cation-π interactions, S-π interactions and hydrophobic interactions. Under the optimal adsorption conditions, the adsorption efficiency of VPBA-SH-IL for six cytokinins could reach more than 95 %, and the adsorption capacities ranged from 0.18 to 0.99 mg·m-1. A reliable and sensitive method for the determination of six cytokinins in organs of tomato (root, stem, leaf and fruit) was established by using the monolithic capillary column as in-tube solid-phase microextraction coupled with UHPLC-MS/MS. The developed method showed a wide linear range (0.010-10.0 μg·L-1) and low limits of detection (1.6-3.3 ng·L-1). The recoveries of the six cytokinins in spiked samples ranged from 80.6 % to 108 % with the relative standard deviations of 2.4-8.7 % (n = 5). The VPBA-SH-IL shows good potential for extraction and analysis of trace cytokinins in complex matrices such as plants, which is of great significance in exploring the mechanism of plant growth and development.

Speciation of selenium-containing small molecules in urine and cell lysate by CE-ICPMS with in-capillary enrichment

The quantitative speciation of selenium in biological systems is highly important for evaluating health status and elucidating transformations of Se species in physiological and pathological processes. Hyphenation of capillary electrophoresis with inductively coupled plasma mass spectrometry (CE-ICPMS) is promising for this purpose. However, the unfavorable or insufficient sensitivity for selenium analysis with CE-ICPMS seriously limits its practical applications in biological analysis, e.g., cell analysis. Therefore, it is crucial to improve the detection sensitivity for Se species. In this study, CE-ICPMS sensitivities for five selenium species (selenocystamine (SeA), methyl-2-acetamido-2-deoxy-1-seleno-β-d-galactopyranoside (SeSug 1), selenomethionine (SeMet), Se-Methylselenocysteine (MeSeCys) and selenocystine (SeCys)) were improved by in-capillary stacking via pH gradient between the zones of sample-leading buffer and the incorporation of isopropanol. The improvement on sensitivity of up to 9.9 folds was achieved in different biological samples, with LODs of 0.29-0.52 μg L-1. This approach was further applied for Se speciation in cell lysate, urine and culture medium. It showed that SeMet was more readily reduced in the medium and favorably accumulated by HepG2, HuH-7 and HCCLM3 cells with respect to SeSug 1 and MeSeCys. In cells, all the three Se species were largely transformed into other Se species. Furthermore, more than 70 % of SeMet reduced in medium was transformed into unknown Se species after 48-h interaction with cells.

Advances in the development of N-glycopeptide enrichment materials based on hydrophilic interaction chromatography

Protein glycosylation is one of the most important post-translational modifications, implicated in the development of various diseases, including neurodegenerative diseases, diabetes, and cancers. However, the low content of glycoproteins in biological samples, the diversity and heterogeneity of glycan structures, and insensitive detection methods make glycosylation analysis challenging. As a result, efficient enrichment of glycopeptides from complex samples is a critical step. Efficient enrichment technology can increase the abundance of intact N-glycopeptides in complex biological samples, thereby improving the sensitivity and coverage of glycosylation analysis, which is of great significance for the accurate identification of biomarkers and the development of glycopeptide-based drugs. Among various separation methods for N-glycopeptides, hydrophilic interaction chromatography has received increasing attention, and a variety of enrichment materials have been developed. This article classifies and describes the relevant hydrophilic interaction chromatography materials and provides a comprehensive review of their applications in N-glycopeptide enrichment regarding selectivity, sensitivity, and enrichment performance. Future development trends of ideal glycopeptide enrichment materials are also discussed.

Biologically-driven RAFT polymerization-amplified platform for electrochemical detection of antibody drugs

The individualized administration and pharmacokinetics profiling are integral to the safe use of antibody drugs in immunotherapy. Here, we propose an electrochemical platform for the highly sensitive and selective detection of antibody drugs, taking advantage of the affinity capture by the peptide mimotopes together with the signal amplification by the biologically-driven RAFT polymerization (BDRP). Briefly, the BDRP-based platform involves the capture of antibody drugs by peptide mimotopes, the labeling of multiple reversible addition-fragmentation chain-transfer (RAFT) agents to the glycan chains of antibody drugs, and the BDRP-enabled controlled recruitment of numerous redox labels. The BDRP-based signal amplification relies on the reduction of RAFT agents by NADH coenzymes into the carbon-centered radicals, which can propagate efficiently into long polymer chains by reacting with the ferrocene-derivated monomers, recruiting numerous redox labels to the glycan chains of antibody drugs. The BDRP is conducted at the physiological temperature (i.e., 37 °C) and in the absence of external stimuli or radical sources, holding the advantages of biological compatibility and desirable simplicity over conventional RAFT polymerization approaches. The developed platform is highly selective and the detection limit in the presence of rituximab as the target was determined to be 0.14 ng/mL. Moreover, the applicability of the BDRP-based platform in the sensitive assay of antibody drugs in serum samples has been validated. In view of the biocompatibility, desirable simplicity, and cost-effectiveness, the BDRP-based platform shows great promise in the quantitative assay of antibody drugs.

Biotemplated Platinum Nanozymes: Synthesis, Catalytic Regulation and Biomedical Applications

Platinum (Pt) nanozymes with multiple intrinsic enzyme-mimicking activities have attracted extensive attention in biomedical fields due to their high catalytic activity, ease of modification, and convenient storage. However, the Pt nanozymes synthesized by the traditional method often suffer from uncontrollable morphology and poor stability under physicochemical conditions, resulting in unsatisfactory catalytic behavior in practical applications. To optimize the catalytic ability, biological templates have been introduced recently, which can guide the deposition of platinum ions on their surface to form specific morphologies and then stabilize the resulting Pt nanozymes. Given the promising potential of biotemplated Pt nanozymes in practical applications, it is essential to conduct a systematic and comprehensive review to summarize their recent research progress. In this review, we first categorize the biological templates and discuss the mechanisms as well as characteristics of each type of biotemplate in directing the growth of Pt nanozyme. Factors that impact the growth of biotemplated Pt nanozymes are then analyzed, followed by summarizing their biomedical applications. Finally, the challenges and opportunities in this field are outlined. This review article aims to provide theoretical guidance for developing Pt nanozymes with robust functionalities in biomedical applications.

Adhesive lipophilic gels delivering rapamycin prevent oral leukoplakia from malignant transformation

Oral leukoplakia (OLK) is the most emblematic oral potentially malignant disorder that may precede the diagnosis of oral squamous cell carcinoma (OSCC) and has an overall malignant transformation rate of 9.8 %. Early intervention is crucial to reduce the malignant transformation rate from OLK to OSCC but the lack of effective local pharmaceutical preparations poses a challenge to clinical management. Rapamycin is speculated to prevent OLK from carcinogenesis and its inherent lipophilicity facilitates its penetration into stratum corneum. Nevertheless, hydrophilic hydrogels frequently encounter challenges when attempting to deliver lipophilic drugs. Furthermore, the oral cavity presents a complex environment defined by oral motor functions, saliva secretion cycles, dynamic fluctuations, and protective barriers comprising mucus and lipid layers. Consequently, addressing issues of muco-penetration and muco-adhesion is imperative for developing an effective drug delivery system aiming at delivering rapamycin to target oral potentially malignant disorders. Here, a dual-function hydrogel drug delivery system integrating adhesion and lipophilicity was successfully developed based on polyvinyl alcohol (PVA) and dioleoyl phosphatidylglycerol (DOPG) via dynamic boronic ester bonds. Rheological experiments based on orthogonal design revealed that PVA-DOPG hydrogels exhibited ideal adhesive strength (around 6 kPa) and could adhere to various surfaces in both dry and wet conditions. PVA-DOPG hydrogels also significantly promoted lipophilic molecules' penetration into stratum corneum (integrated fluorescence density of 6.95 ± 0.52 × 106 and mean fluorescence depth of 0.96 ± 0.07 mm) of ex-vivo porcine buccal mucosa (p < 0.001). Furthermore, PVA-DOPG hydrogels incorporating rapamycin inhibited malignant transformation of OLK mouse model induced by 4-Nitroquinoline N-oxide (4-NQO), distinct improvements in survival (the neoplasm incidence density at the 40th day is 0.0091) (p < 0.05), decrease in neoplasm incidence density of 36.36 % and inhibition rate in neoplasm volume of 75.04 ± 33.67 % have been demonstrated, suggesting the hydrogels were valuable candidates for potential applications in the management of OLK.

Zein and 3-Aminophenyl Boronic Acid Conjugated Polyvinylpyrrolidone Polymer Blend: Electrospinning, Characterization, and Mucoadhesive Drug Delivery

The era of mucoadhesive polymers has advanced to the next generation, focusing on targeted adhesion of chemical functional groups with mucosa. This work aims to develop boronic acid functionalized polymers, which could facilitate reversible binding with the mucin in the mucosa. Pendant groups of boronic acid were conjugated on the chains of polyvinylpyrrolidone (PVP) via C═N bonding. The evidence from FTIR spectroscopy, XPS analysis, and UV spectroscopy has been used for the confirmation of the chemical conjugation of 3-aminophenyl boronic acid (APBA) to PVP. Boronate ester formation is a pH-dependent process. High pKa values of APBA preferably cause the binding of trigonal-shaped boronic acid with sialic acid groups of mucin. Boronic acid moieties additionally benefited in mucoadhesion in comparison to PVP alone, which is a result of the formation of a five-membered boronate ester complex. The presence of boronic acid moieties enhanced the force of adhesion on porcine buccal mucosal tissue from 13.12 ± 1.52 to 19.04 ± 1.97 g force. Specific binding of the polymer to the mucosal surface caused prolonged adhesion of the polymer to the mucosal surface. A polymer blend of boronic acid functionalized PVP and zein has been explored for its potential for mucoadhesive delivery of propranolol hydrochloride.

Effective enrichment of glycated proteome using ultrasmall gold nanoclusters functionalized with boronic acid

Glycated proteins play a crucial role in various biological pathways and the pathogenesis of human diseases. A comprehensive analysis of glycated proteins is essential for understanding their biological significance. However, their low abundance and heterogeneity in complex biological samples necessitate an enrichment procedure prior to their detection. Current enrichment strategies primarily rely on the boronic acid (BA) affinity method combined with functional nanoparticles; however, the effectiveness of these approaches is often suboptimal. In this study, a novel nanocluster (NC)-based enrichment material was synthesized for the first time, characterized as Au22SG18 functionalized with 24 BA groups, in which SG is glutathione. The functionalized BA established a reversible covalent bond with the cis-dihydroxy group through pH adjustment, enabling selective enrichment of glycated peptides. After the optimization of the enrichment protocol, we demonstrated highly sensitive and selective enrichment of standard glycopeptides using the NC-based enrichment material, exhibiting excellent reusability. Efficient enrichment was also demonstrated for the glycated proteome from human serum. These results highlight the potential of the atomically well-defined ultrasmall Au NCs as a powerful tool for high-throughput analysis of glycated peptides.

Boronic Acid-Based Glucose Detection for Liver Three-Dimensional Cellular Models

Liver 3D cell models are regularly employed as a screening platform for predicting the metabolic safety of drugs, by monitoring the physiological responses of the spheroids, through the measurement of relevant markers of normal liver physiology, notably glucose. Measuring glucose levels within the spheroids and their surroundings provides insight into the metabolic homeostasis of liver cells and may be employed as an indication of potential drug-induced toxicity. Several ortho-aminomethyl phenylboronic acid (PDBA) glucose sensors have been developed. Most recently, Mc-CDBA ((((((2-(methoxycarbonyl)anthracene-9,10-diyl)bis(methylene)) bis(methylazanediyl))bis(methylene))bis(4-cyano-2,1-phenylene))diboronic acid) was reported. Although Mc-CDBA exhibits good water solubility and sensitivity toward glucose, its ability for intra- and extracellular glucose monitoring in spheroids has not been determined. Here, we present a set of Mc-CDBA derivatives: carboxylic (BA) and amide (BA 5)-based Mc-CDBA sensors for extra- and intracellular glucose monitoring, respectively. Both sensors exhibit superior spectroscopic features. BA 5 showed selective intracellular accumulation in liver spheroids and exhibited more than 3-fold higher basal fluorescence sensitivity compared to Mc-CDBA. These observations led to the development of an extracellular hydrogel-embedded sensor (HG-BA 21) to monitor extracellular glucose levels under persistent solution flow mimicking physiological conditions. We have therefore demonstrated that the sensors developed by our team are suitable for a variety of assays, notably with liver spheroids, and provide powerful new tools for organ-on-a-chip applications predicting drug-induced liver injury in the early stages of drug development.

Phenylboronic acid-functionalized biomaterials for improved cancer immunotherapy via sialic acid targeting

Phenylboronic acid (PBA) is recognized as one of the most promising cancer cell binding modules attributed to its potential to form reversible and dynamic boronic ester covalent bonds. Exploring the advanced chemical versatility of PBA is crucial for developing new anticancer therapeutics. The presence of a specific Lewis acidic boron atom-based functional group and a Π-ring-connected ring has garnered increasing interest in the field of cancer immunotherapy. PBA-derivatized functional biomaterials can form reversible bonds with diols containing cell surface markers and proteins. This review primarily focuses on the following topics: (1) the importance and versatility of PBA, (2) different PBA derivatives with pKa values, (3) specific key features of PBA-mediated biomaterials, and (4) cell surface activity for cancer immunotherapy applications. Specific key features of PBA-mediated materials, including sensing, bioadhesion, and gelation, along with important synthesis strategies, are highlighted. The utilization of PBA-mediated biomaterials for cancer immunotherapy, especially the role of PBA-based nanoparticles and PBA-mediated cell-based therapeutics, is also discussed. Finally, a perspective on future research based on PBA-biomaterials for immunotherapy applications is presented.

Oriented surface imprinted 96-well microplate-based fluorescent biosensor for glycoprotein detection by boronate affinity sandwich assay

Glycoproteins perform vital functions in numerous biological processes and have important clinical implications. Many glycoproteins have been used as biomarkers and therapeutic targets for disease diagnosis. Due to low concentration of glycoprotein biomarkers and the presence of high-abundance interfering species in biological samples, a selective and sensitive detection method for glycoprotein is essential for real-world applications. In this study, we develop an oriented surface imprinted microplate-based fluorescent biosensor by boronate-affinity sandwich assay (BASA) for the specific, sensitive and high throughput determination of glycoproteins in complex samples. The structure of the BASA is based on sandwich formation between boronate affinity-oriented surface-imprinted microplates, target glycoproteins, and boronate affinity fluorescence probes. The imprinted microplates ensure the high specificity, high affinity and high throughput, while the fluorescence probes, consisting of boronic acid-modified CdTe QDs, provide high sensitivity. The proposed approach could exhibit a wide linear range of 1 ng/mL-105 ng/mL, with a low LOD of 0.528 ng/mL using horseradish peroxidase (HRP) as a model glycoprotein. As compared with traditional "turn off" fluorescent sensor, the developed "turn on" fluorescent sensor provided three orders of magnitude higher sensitivity at least. The fluorescent biosensor achieved average recoveries ranging from 96.8 % to 106.0 % in urine samples.

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.

Revolutionizing the capture efficiency of ultrasensitive digital ELISA via an antibody oriented-immobilization strategy

Bead-based digital ELISA, the most sensitive protein quantification method, has drawn much attention to exploring ultra-low abundance biomarkers in the life sciences and clinical applications. However, its major challenge refers to the low antigen capture efficiency in the immunoreaction process due to the low probability of collision between the deficient concentration of the analytes and the captured antibody-immobilized on the beads. Here, we achieved significantly improved reaction efficiency in the digital signal formation by fixing the orientation of antibodies and revealed the kinetic mechanism for the first time. A facile and fast antibody conjugation strategy that formed boronate ester complexes was designed to retain the uniform orientation of antibodies with controllable antibody density. Remarkably, the oriented immobilized antibody exhibited stronger antigen-binding capacity and faster antigen-binding speed compared to randomly immobilized antibodies, with capture efficiency increasing approximately 14-fold at 15 μg of antibody per 1 mg microbeads (0.035 antibody nm-2) under 0.5 h incubation. Combined with theoretical analysis, we verified that the improved capture efficiency of the oriented antibodies mainly originated from the considerable rise in the binding rate constant (kon) rather than the increase in antigen-binding sites, which further prominently decreased the limit of detection (LoD) in a shorter incubation time compared with the randomly immobilized antibody. In conclusion, the antibody oriented conjugation method effectively overcomes the low capture efficiency challenge of bead-based digital ELISA. It paves a promising way for further improving the digital immunoassay performance and promotes the early diagnosis of diseases by recognizing more ultra-low abundance significant biomarkers.

Metal Ion-/Proton-Coupled Electron Transfer (MPCET) on ortho-Quinone

Quinol/quinone equilibria are ubiquitous in nature and find multiple technological applications, most recently in electrical charge storage. Much research has been devoted to proton-coupled electron transfer (PCET) in such systems and to bidentate complexation of ortho-quinol (catechol) ligands with multivalent metal ions but rarely to the interplay of these two reactions. Here, we investigate the impact of a redox-inactive metal ion, as a complexing and charge-compensating agent, on redox processes of catechol in aqueous solutions, that is, in the presence of proton equilibria. We pay separate attention to their thermodynamics and kinetics, which can be regulated by the pH and buffer capacity. As the proton buffer concentration decreases, proton equilibria during catechol PCET are slower to establish, thus kinetically prioritizing the participation of the metal ion rather than the proton in the redox charge compensation. Making use of this kinetic interplay can be a general strategy to conceive organic battery cathodes for proton-free metal-ion aqueous batteries.

Properties, evaluation and application of naringin magnetic molecularly imprinted polymer based on synergistic imprinting strategy

A novel and facile surface molecularly imprinted polymer coated on magnetic chitosan (Fe3O4@CS@MIP) was fabricated for the selective recognition and enrichment of naringin (NRG). The Fe3O4@CS@MIP was prepared based on covalent-noncovalent synergistic imprinting strategies, utilizing 4-vinyl phenyl boric acid as covalent functional monomer, deep eutectic solvent (choline chloride/methacrylic acid [ChCl/MAA]) as non-covalent functional monomer and Fe3O4@CS nanoparticles as the magnetic support. The obtained Fe3O4@CS@MIP exhibited a uniform morphology, excellent crystallinity, outstanding magnetic properties, and high surface area. Owing to the double recognition abilities, the resultant polymer showed exceptional binding performance and rapid mass transfer in phosphate buffer (pH 7.0). The maximum binding amount of Fe3O4@CS@MIP was found to be 15.08 mg g-1, and the equilibrium adsorption could be achieved within 180 min. Moreover, they also exhibited stronger selectivity for NRG and satisfactory reusability, with only 11.0% loss after five adsorption-desorption cycles. Additionally, the Fe3O4@CS@MIP, serving as an adsorbent, presented practical application potential in the separation and enrichment of NRG from pummelo peel, with extraction efficiency in the range of 79.53% to 84.63%. This work provided a new strategy for improving the performance of MIP and contributed an attractive option for the extraction of NRG in complex samples.

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.

A Highly Efficient Fluorescent Turn-Off Nanosensor for Quantitative Detection of Teicoplanin Antibiotic from Humans, Food, and Water Based on the Electron Transfer between Imprinted Quantum Dots and the Five-Membered Cyclic Boronate Esters

Teicoplanin has been banned in the veterinary field due to the drug resistance of antibiotics. However, teicoplanin residue from the antibiotic abuse of humans and animals poses a threat to people's health. Therefore, it is necessary to develop an efficient way for the highly accurate and reliable detection of teicoplanin from humans, food, and water. In this study, novel imprinted quantum dots of teicoplanin were prepared based on boronate affinity-based precisely controlled surface imprinting. The imprinting factor (IF) for teicoplanin was evaluated and reached a high value of 6.51. The results showed excellent sensitivity and selectivity towards teicoplanin. The relative fluorescence intensity was inversely proportional to the concentration of teicoplanin, in the range of 1.0-17 μM. And its limit of detection (LOD) was obtained as 0.714 μM. The fluorescence quenching process was mainly controlled by a static quenching mechanism via the non-radiative electron-transfer process between QDs and the five-membered cyclic boronate esters. The recoveries for the spiked urine, milk, and water samples ranged from 95.33 to 104.17%, 91.83 to 97.33, and 94.22 to 106.67%, respectively.

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.

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.

Harnessing a bis-electrophilic boronic acid lynchpin for azaborolo thiazolidine (ABT) grafting in cyclic peptides

Chemical modifications of native peptides have significantly advanced modern drug discovery in recent decades. On this front, the installation of multitasking molecular grafts onto macrocyclic peptides offers numerous opportunities in biomedical applications. Here, we showcase a new class of borono-cyclic peptides featuring an azaborolo thiazolidine (ABT) graft, which can be readily assembled utilizing a bis-electrophilic boronic acid lynchpin while harnessing the inherent reactivity difference (>103 M-1 s-1) between the N-terminal cysteine and backbone cysteine for rapid and highly regioselective macrocyclization (∼1 h) under physiological conditions. The ABT-crosslinked peptides are fairly stable in endogenous environments, but can provide the linear diazaborine peptides via treatment with α-nucleophiles. This efficient peptide crosslinking protocol was further extended for regioselective bicyclizations and engineering of α-helical structures. Finally, ABT-grafted peptides were exploited in biorthogonal conjugation, leading to highly effective intracellular delivery of an apoptotic peptide (KLA) in cancer cells. The mechanism of action by which ABT-grafted KLA peptide induces apoptosis was also explored.

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.

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.