Boronic Acid Groups Research Articles

Injectable chitosan hydrogels tailored with antibacterial and antioxidant dual functions for regenerative wound healing

Herein, an injectable self-healing hydrogel with inherent antibacterial activity was fabricated based on the dynamic covalent bond formation between boronic acid and catechol groups in quaternized chitosan as building blocks in conjunct with the in-situ encapsulation of epigallocatechin-3-gallate (EGCG, a green tea derivative). Benefiting from the catechol groups and therapeutic effect of EGCG, the resulting natural-based injectable hydrogels showed excellent antibacterial and antioxidant dual functions in preventing bacterial infection and scavenging radicals. The hydrogels loaded with EGCG also exhibited good biocompatibility along with contact-active antibacterial activity via a “capture and kill” strategy. The dynamic covalent bonding enables shear-thinning delivery of the gels via syringe, followed by rapid self-healing. Additionally, the in vivo wound healing evaluation in a full-thickness skin defect model revealed the appreciable and regenerative wound healing performance of the hydrogels, demonstrating their great potential as novel wound dressings for wound management.

Enhanced photoactivity of Bi2S3 nanoflowers by CS-AgBr and CeO2: Application in photoelectrochemical biosensor for the effect of antibiotics on N6-methyladenosine in rice tissues

• The CS-AgBr greatly improves the photoelectric activity of Bi 2 S 3 . • N 6 -methyladenosine-5′-triphosphate was specifically recognized and detected by PEC biosensor. • The photocurrent response is enhanced by the band matching of Bi 2 S 3 /CS-AgBr/CeO 2 . • The effect of three antibiotics on m 6 ATP expression in rice seedlings was investigated. CS-AgBr and octahedral CeO 2 greatly enhanced the photoactivity of Bi 2 S 3 nanoflowers due to the Bi 2 S 3 can form an energy band match with CS-AgBr and CeO 2 , which can accelerate electron transfer and reduce photogenerated electron-hole pair recombination. Thus, CeO 2 /CS-AgBr/Bi 2 S 3 exhibits good photoelectrochemical (PEC) response. With this as a basis, a novel PEC immunosensor was intended for N 6 -methyladenosine-5′-triphosphate (m 6 ATP) detection, in which m 6 ATP antibody was applied as the recognition unit for m 6 ATP, Bi 2 S 3 /CS-AgBr was utilized towards the photoactive material, and CeO 2 was employed as the signal amplification unit. m 6 ATP antibody was firstly captured on CPBA/CS-AgBr/Bi 2 S 3 /ITO surface through the covalent reaction between the boronic acid group of 4-carboxyphenylboronic acid (CPBA) and the o-diol structure of m 6 ATP antibody. Then, m 6 ATP was specifically recognized based on the specific immune reaction between the antigen and the antibody. Finally, signaling amplification unit of CeO 2 achieved signal enhancement through the capture of the phosphate group of m 6 ATP. Under optimal conditions, the PEC biosensor exhibited a wide linear range of 0.001–150 nM and a low detection limit of 0.48 pM (3σ). The suitability was assessed by investigating the results of the effect of antibiotics on the m 6 A levels in total RNA of rice root and leaf tissues. The results indicated that all of the three antibiotics (tobramycin, amoxicillin and chloramphenicol) inhibited the expression of m 6 ATP within 1, 4 and 7 days of cultivation.

Highly sensitive detection of fluoride based on poly(3-aminophenylboronic acid)-reduced graphene oxide multilayer modified electrode

A novel electrochemical method for detecting fluoride was developed based on gold electrode modified by layer-by-layer (LBL) assembly of poly(3-aminophenylboronic acid)-reduced graphene oxide (PAPBA-RGO) multilayers. The PAPBA-RGO multilayer-modified gold electrode was constructed by using alternating LBL assembly of RGO and PAPBA on a bare gold electrode by one-step electrodeposition. Fluoride was electrochemically determined based on the proposed modified electrode by evaluating the changes in peak current for potassium ferricyanide reduction caused by the conjunction of fluoride and boronic acid groups of PAPBA. The results indicated that the peak current for potassium ferricyanide reduction obviously decreased with the increasing fluoride concentration. The response range of our method for fluoride was 1 × 10–8 to 1 × 10–1 M with a detection limit of 6 × 10–10 M and high sensitivity and selectivity. This method was applied to detect fluoride in tap water, rice, apple, and edible fungi samples.

Dietary Flavonoids with Catechol Moiety Inhibit Anticancer Action of Bortezomib: What about the other Boronic Acid-based Drugs?

Approval of the first boronic acid group-containing drug, bortezomib, in 2003 for the treatment of multiple myeloma sparked an increased interest of medicinal chemists in boronic acidbased therapeutics. As a result, another boronic acid moiety-harboring medication, ixazomib, was approved in 2015 as a second-generation proteasome inhibitor for multiple myeloma; and dutogliptin is under clinical investigation in combination therapy against myocardial infarction. Moreover, a large number of novel agents with boronic acid elements in their structure are currently in intensive preclinical studies, allowing us to suppose that at least some of them will enter clinical trials in the near future. On the other hand, only some years after bortezomib approval, direct interactions between its boronic acid group and catechol moiety of green tea catechins as well as some other common dietary flavonoids like quercetin and myricetin were discovered, leading to the formation of stable cyclic boronate esters and abolishing the anticancer activities. Although highly relevant, to date, no reports on possible co-effects of catechol group-containing flavonoids with new-generation boronic acidbased drugs can be found. However, this issue cannot be ignored, especially considering the abundance of catechol moiety-harboring flavonoids in both plant-derived food items as well as over-thecounter dietary supplements and herbal products. Therefore, in parallel with the intensified development of boronic acid-based drugs, their possible interactions with catechol groups of plant-derived flavonoids must also be clarified to provide dietary recommendations to patients for maximizing therapeutic benefits. If concurrently consumed flavonoids can indeed antagonize drug efficacy, it may pose a real risk to clinical outcomes.

Self-calibration SERS sensor with “core-satellite” structure for detection of hyaluronidase activity

Hyaluronidase expression is known to be upregulated in various pathological conditions. A method based on a combination of ratiometric surface-enhanced Raman scattering (SERS) and magnetic separation is described for the determination of hyaluronidase (HAase) activity. Gold nanospheres (AuNPs) functionalized by 4-mercaptophenylboronic acid (4-MPBA) form stable cyclic esters with diol on hyaluronic acid (HA) by the boronic acid group, while Fe3O4@DTNB@Au modified with mercaptoethylamine (MEA) was used as a capture substrate to bind to the carboxyl group on the surface of HA, forming the “Au@4-MPBA@HA/Fe3O4@DTNB@Au@MEA” “core-satellite” structure. When HAase is present, HA is enzymatically disrupted, resulting in the destruction of the “core-satellite” structure, the SERS signal of 4-MPBA is subsequently weakened. The gold shell in the substrate protects the 5,5′-Dithio bis-(2-nitrobenzoic acid) (DTNB) from the external environment, which makes it become an ideal internal standard (IS) molecule for subsequent calibration. Under optimal conditions, the I1075/I1324 varied in the range of 10−3 - 10 U‧mL−1 HAase activity, with a limit of detection (LOD) of 0.32 mU‧mL−1，below the level of HAase in normal human body fluids. This method has been successfully applied to the determination of HAase activity in urine and is expected to provide a new method in disease detection, especially in the non-invasive detection of bladder cancer.

All‐Small‐Molecule Dynamic Covalent Hydrogels with Heat‐Triggered Release Behavior for the Treatment of Bacterial Infections

AbstractAll‐small‐molecule smart hydrogels fabricated by naturally occurring and commercially available small molecular building blocks have attracted increasing interest due to their unique features such as biofunction integration and multi‐stimuli responsiveness. While a few examples have been well‐explored, the further development of additional kinds of all‐small‐molecule smart hydrogels is severely hindered by the lack of enough commensurate building blocks from nature and market. Therefore, it is crucial to seek new strategies to expand the scope of all‐small‐molecule dynamic covalent hydrogels using well‐established natural and commercial chemicals. Herein, this issue is addressed by introducing a bifunctional adapter bearing an aldehyde group and a boronic acid group to construct a novel all‐small‐molecule smart hydrogel through the dynamical covalent cross‐linking with naturally occurring building blocks (e.g., tobramycin and tannic acid). The prepared hydrogel presents several promising features including tunable mechanical property, multi‐stimuli responsiveness, controlled drug release profiles, and excellent in vitro and in vivo antibacterial performances. This study provides a new strategy to efficiently expand the scope of the all‐small‐molecule smart hydrogels via the integration of the naturally occurring building blocks and the bifunctional adapters.

3-Aminobenzeneboronic acid self-assembled monolayer-modified ITO for efficient and stable OLED devices

Interface modification of indium tin oxide (ITO) is a hot research topic to obtain highly efficient and stable organic light-emitting diodes (OLEDs), and the key point is to improve the hole injection efficiency between the electrode and organic layer. In this study, we demonstrate an optimization strategy based on the use of 3-aminobenzeneboronic acid (3ABBA) for modifying ITO at the anode interface. The protonation reaction of boronic acid groups with oxides and hydroxyl groups forms a self-assembled monolayer (SAM). Since the ionization potential (IP) of 3ABBA-SAM is 5.44 eV, the hole injection barrier at the interface is minimized. Compared with a control device using PEDOT:PSS, the synergistic effects of the optimized 3ABBA-SAM significantly improves the maximum power efficiency (PEmax of 8.52 lm W−1) and maximum current efficiency (CEmax of 10.45 cd A−1) of the device, and the turn-on voltage is reduced by 0.2 V. In addition, effective interface modification reduces the hydrophilicity of the device and provides support for the stability of the OLED in the ambient environment. Therefore, we believe that a simple 3ABBA-SAM interface modification project can promote the development of high-performance and low-cost OLEDs.

Hydroboration of Hollow Microporous Organic Polymers: A Promising Postsynthetic Modification Method for Functional Materials.

This work shows that hydroboration can be efficiently applied to the postsynthetic modification (PSM) of the Sonogashira-Hagihara coupling-based microporous organic polymers (MOPs). Hollow MOPs (H-MOPs) were prepared by template synthesis through the Sonogashira-Hagihara coupling of tetra(4-ethynylphenyl)methane with 1,4-diiodobenzene. The H-MOPs were used as platforms in the PSM-based functionalization. The heat-treatment of H-MOPs in the presence of a neat pinacolborane reagent resulted in the successful addition of pinacolborane groups to the internal alkynes of H-MOPs, generating H-MOPs with pinacolboranes (H-MOP-BPs). The pinacolborane moieties in the H-MOP-BP were further converted to boronic acid groups. The resultant H-MOP-BAs were used as heterogeneous organocatalysts in the CO2 fixation with epoxides to cyclic carbonates at ambient temperature (50 °C). Moreover, H-MOP-BAs could be recycled with retention of the catalytic performance in five successive reactions.

Templating precise multiple binding sites: Promising molecularly imprinted membrane orchestrated by sequential surface imprinting strategy

Olive mill wastewater (OMW) is a hazardous environmental effluent due to its high phenolic compounds (PCs) content. Novel strategies affording molecular precision and functional versatility are needed to recover PCs and reduce ecotoxicity. Luteolin (LTL) was selected as a typical PC in the OMW. In this study, we outlined a molecularly imprinted membrane (MPL@CSMIMs) orchestrated by a sequential surface imprinting strategy to selectively separate LTL. Dopamine (DA), as a multifunctional monomer, could self-polymerize in an alkaline solution to form the first LTL-imprinting procedure. A polydopamine (PDA) modulated bottom-up approach was regarded as a molecular linker to enhance the hydrophilicity and binding activity, as well as established a strong and stable adhesion platform for integrated structure. The second imprinting procedure was formed by atom transfer radical polymerization (ATRP). The covalent and non-covalent functional monomers (boronic acid and amino groups) were introduced to create the tailor-made second-imprinted sites. Adsorption isotherm and dynamics, permeation selectivity, and stability were investigated, possessing desirable rebinding ability (49.63 mg g−1) and permselectivity factors (βAGN/LTL = 5.80, βCTC/LTL = 12.82), respectively. In-situ diffuse reflection infrared Fourier transform spectroscopy (In-situ ATR-FTIR) analysis, molecular simulation, and X-ray photoelectron spectroscopy (XPS) analysis revealed that the templating precise adsorption property for LTL was mainly realized by the shape of LTL-imprinted sites and synergistic covalent and non-covalent interactions. Compared to one-step or one-pot imprinting approaches, the proposed sequential surface imprinting strategy offered a more flexible and precise combination to improve the selectivity of MIMs significantly. The efficiency of the sequential imprinting approach made it a competitive and appealing method to develop MIMs.

Boronic acid grafted metal-organic framework for selective enrichment of cis-diol-containing compounds

This study constructed boronic acid grafted Zr-MOF (BA-Zr-MOF) by a simple pre-installation strategy through mixed organic ligands. Typically, BA-Zr-MOF was prepared by one-step hydrothermal method used for enrichment of cis-diol-containing nucleosides through pipette tip solid-phase extraction (PT-SPE) followed by detection of high-performance liquid chromatography. It is worth mentioning that BA is well assembled into MOF and cis-diol-containing compounds can be efficiently and selectively enriched by abundant boronic acid groups. Three groups of different types of compounds were used to evaluate their selectivity and the results showed the excellent selectivity to cis-diol-containing compounds of as-prepared adsorbent. The BA-Zr-MOF adsorbent possesses a high adsorption capacity, which can reach 86.40 mg g−1 for adenosine. Under the optimal extraction condition, a PT-SPE-HPLC method based on BA-Zr-MOF for analysis of nucleosides was established. The linear range of the four nucleosides is 0.01 to 50 µg mL−1 with R2 ≥ 0.99 and the detection limits (LODs) are estimated at between 0.005-0.012 µg mL−1. The recoveries in urine were used to test the reliability of the analytical methods, which ranged from 82.8% to 117.1%, with intra-day relative standard deviations (RSDs) ranged from 0.1% to 4.2% and the inter-day RSDs ranged from 0.2% to 6.2%. All the results show that the pre-installation strategy based on dual ligands is an alternative to fabricate MOF composite material and BA-Zr-MOF is a promising material for the analysis of cis-diol-containing biomolecules.

Facile Fabrication of Hierarchically Porous Boronic Acid Group-Functionalized Monoliths With Optical Activity for Recognizing Glucose With Different Conformation.

At present, various materials based on helical polymers are nanoparticle or microsphere, which is not ease of use in practical application. Accordingly, facile preparation hierarchically porous monolith based on helical polymer needs to be developed. Herein, hierarchically porous boronic acid group-functionalized monoliths that exhibited optical activity were fabricated with a facile method based on crosslinking and polymerization-induced phase separation (CPIPS). Chiral substituted acetylene and achiral substituted acetylene with a boronic acid group were used as monomers. By regulating the composition of the pre-polymerization solution, the permeability and macropore size of the porous structure could be controlled. The hierarchically porous structure and large surface area were confirmed by scanning electron microscopy and nitrogen gas adsorption/desorption isotherms. In particular, the boronic acid functional group that can interact with a cis-diol group was successfully introduced on the skeleton surface of the monoliths. Further, the main chain of the copolymer that constituted the monoliths exhibited a high cis content and tacticity, and the monoliths showed good optical activity. Thus, the present study established a facile method to synthesize hierarchically porous boronic acid group-functionalized monoliths with optical activity via CPIPS, and the monoliths showed potential in recognition, separation, and adsorption of compound with chirality and cis-diol groups.

Boronic Acid-Decorated Multivariate Photosensitive Metal-Organic Frameworks for Combating Multi-Drug-Resistant Bacteria.

Metal-organic frameworks (MOFs) are promising photosensitized materials that have displayed great advantages in antibacterial application. However, their bactericidal activity is still limited by the ultrashort diffusion distance of biocidal reactive oxygen species (ROS). Herein, we integrate the bacterial-binding boronic acid ligand and photosensitized porphyrin into one single MOF, synergistically boosting antibiotic capability. The introduction of the boronic acid group with a closed physical gap makes multivariate MOFs more powerful for eradicating multi-drug-resistant (MDR) bacteria. The MOFs that are decorated with boronic acid possess antibacterial efficiencies (10-20 times) higher than those without the targeting ligand. Moreover, the MOFs exhibit excellent biocompatibility. They significantly decrease the inflammatory responses and accelerate the healing of chronic wounds infected with MDR bacteria (nearly 2 times faster). This work provides a strategy to develop multivariate MOFs that target bacteria, which will further inspire specific bacterial-binding therapy in the future.

Boronate-Based Fluorescent Probes as a Prominent Tool for H2O2 Sensing and Recognition.

Given the crucial association of hydrogen peroxide with a wide range of human diseases, this compound has currently earned the reputation of being a popular biomolecular target. Although various analytical methods have attracted our attention, fluorescent probes have been used as prominent tools to determine H2O2 to reflect the physiological and pathological conditions of biological systems. The sensitive responsive part of these probes is the boronate ester and boronic acid groups, which are important reporters for H2O2 recognition. In this review, we summarize boronate ester/boronic acid group-based fluorescent probes for H2O2 reported from 2012 to 2020, and we have generally classified the fluorophores into six categories to exhaustively elaborate the design strategy and comprehensive systematic performance. We hope that this review will inspire the exploration of new fluorescent probes based on boronate ester/boronic acid groups for the detection of H2O2 and other relevant analytes.

A Radiolabeling Method for Precise Quantification of Polymers

Radiolabeling a protein, molecule, or polymer can provide accurate and precise quantification in biochemistry, biomaterials, pharmacology, and drug delivery research. Herein, we describe a method to 125I label two different polymers for precise quantification in different applications. The surfaces of model contact lenses were modified with phenylboronic acid to bind and release the natural polymer, hyaluronic acid (HA); HA uptake and release were quantified by radiolabeling. In the second example, the in vivo distribution of a mucoadhesive micelle composed of the block copolymer of poly(lactide)-b-poly(methacrylic acid-co-acrylamidophenylboronic acid) was investigated. The presence of phenyl boronic acid groups (PBA), which bind to mucosal surfaces, was proposed to improve the retention of the micelle. 125I labeling of polymers was examined for quantification of microgram amounts of HA present on a contact lens or to evaluate the enhanced retention of PBA micelles on mucosal surfaces in vivo. The introduction of phenol groups onto the polymers allowed for the labeling. HA was modified with phenol groups through a coupling reaction of its carboxylic acid with hydroxybenzylamine. Phenol functional block copolymer micelles with and without PBA were synthesized by including N-(4-hydroxyphenethyl)acrylamide during polymerization. The phenol groups of HA and the block copolymers were labeled with 125I using a modified ICl labeling method. 125I labeling enabled quantification of HA loading and release including the effect of varying amounts of PBA on the contact lens surfaces. Micelles made from 125I-labeled block copolymers with and without PBA were administered intranasally to Brown Norway rats. The animals were sacrificed either immediately after or 4 h after their last nasal instillation, and the nasopharyngeal tissues were removed and quantified. Radioactivity measurements demonstrated that the presence of the PBA mucosal binding groups led to approximately four times higher retention. The HA and block copolymer 125I labeling presented in this article demonstrates the utility of the method for quantification and tracking of microgram quantities of polymers in diverse applications.

Specific and Reversible Enrichment of Early-Stage Glycated Proteome Based on Thiazolidine Chemistry and Palladium-Mediated Cleavage.

Comprehensive analysis of protein glycation is important for better understanding of its formation mechanism and biological significance. The current preconcentration methods of glycated proteome mainly depend on the reversible combination of boronic acid and cis-dihydroxy group by pH adjustment, but it has inherent limitations (e.g., poor specificity and time-consuming). Herein, for the first time, a novel enrichment method for glycated peptides is proposed based on the reversible chemical reaction between aldehyde and 1,2-aminothiol groups, in which oxidized glycated peptides are captured onto the magnetic nanoparticles via thiazolidine chemistry and then released by palladium-mediated cleavage. The method is rapid, with excellent selectivity (even at a 1:1000 molar ratio of glycated peptides/nonglycated peptides) and high sensitivity (1 fmol/μL). As a good evidence, 1549 glycated peptides were identified from glycated human serum with 94.6% specificity, providing a powerful technique for high-throughput analysis of glycated peptides.

Controlled and Predictably Selective Oxidation of Activated and Unactivated C(sp3)-H Bonds Catalyzed by a Molybdenum-Based Metallomicellar Catalyst in Water.

The synthesis of carbonyl derivatives from renewable feedstocks, by direct oxidation/functionalization of activated and unactivated C(sp3)-H bonds under a controlled and predictably selective fashion, especially in late stages, remains a formidable challenge. Herein, for the first time, cost-effective and widely applicable protocols for controlled and predictably selective oxidation of petroleum waste and feedstock ingredients like methyl-/alkylarenes to corresponding value-added carbonyls have been developed, using a surfactant-based oxodiperoxo molybdenum catalyst in water. The methodologies use hydrogen peroxide (H2O2) as an environmentally benign green oxidant, and the reactions preclude the need of any external base, additive, or cocatalyst and can be operated under mild eco-friendly conditions. The developed protocols show a wide substrate scope and eminent functional group tolerance, especially oxidation-liable and reactive boronic acid groups. Upscaled multigram synthesis of complex steroid molecules by late-stage oxidation proves the robustness and practical utility of the current protocol since it employs an inexpensive recyclable catalyst and an easily available oxidant. A plausible mechanism has been proposed with the help of few controlled experiments and kinetic and computational studies.

Molecularly imprinted polymer based electrochemical sensor for quantitative detection of SARS-CoV-2 spike protein

The continued spread of the coronavirus disease and prevalence of the global pandemic is exacerbated by the increase in the number of asymptomatic individuals who unknowingly spread the SARS-CoV-2 virus. Although remarkable progress is being achieved at curtailing further rampage of the disease, there is still the demand for simple and rapid diagnostic tools for early detection of the COVID-19 infection and the following isolation. We report the fabrication of an electrochemical sensor based on a molecularly imprinted polymer synthetic receptor for the quantitative detection of SARS-CoV-2 spike protein subunit S1 (ncovS1), by harnessing the covalent interaction between 1,2-diols of the highly glycosylated protein and the boronic acid group of 3-aminophenylboronic acid (APBA). The sensor displays a satisfactory performance with a reaction time of 15 min and is capable of detecting ncovS1 both in phosphate buffered saline and patient’s nasopharyngeal samples with LOD values of 15 fM and 64 fM, respectively. Moreover, the sensor is compatible with portable potentiostats thus allowing on-site measurements thereby holding a great potential as a point-of-care testing platform for rapid and early diagnosis of COVID-19 patients.

A pH Self‐Monitoring Heterogeneous Multicompartmental Proteinosome with Spatiotemporal Regulation of Insulin Transportation

Main observation and conclusionInspired by the intricate eukaryotic cell structure, the spontaneously assembling multicompartments capable of spatiotemporally regulated biomacromolecules transportation is still a challenge. Here, a heterogeneous proteinosome‐based multicompartment was designed and constructed by combining aqueous two‐phase system and Pickering emulsion methods. By loading PEGylated insulin with boronic acid group into the multicompartment and glucose oxidase (GOx) into the innermost microgel domain, a short‐ or long‐term transportation pathway of the loaded insulin was constructed by responding to the concentration of glucose. Moreover, the diminution of dynamic boronic ester bonding, the hindrance of polyethylene oxide micro‐chamber, electrostatic interaction and the swelling behavior of hydrogel triggered by GOx/glucose reaction resulted in spatiotemporally controlled multi‐pathway transportation mode with the releasing of insulin loaded inside the innermost microgel at high concentration of glucose (10 mg·mL–1). Specially, by incorporating rhodamine B and fluorescein labelled BSA into the multicompartment, the release procedure of the loaded insulin can be monitored by the fluorescence color‐change. Overall, a multimode microcompartment is constructed which is then expected to provide a promising platform for further therapeutic protein, gene and drug delivery, as well as towards the design of complicated cell biomimetics.

A colorimetric and SERS dual-readout sensor for sensitive detection of tyrosinase activity based on 4-mercaptophenyl boronic acid modified AuNPs

Tyrosinase (TYR) is as a well-known polyphenol oxidase and important biomarker of melanocytic lesions. Thus, developing powerful methods to determine TYR activity is of great value in the early diagnosis of skin disease. Direct surface-enhanced Raman scattering (SERS) detection of biomolecules is usually affected by non-specific interference and complicate structure of the analytes. It is a challenge to develop Raman-active molecules with specific recognition to analytes in complex media. Here, we report a novel colorimetric and surface-enhanced Raman scattering (SERS) dual-readout assay for the determination of TYR using commercially available and economical 4-mercaptophenyl boronic acid (4-MPBA) as a Raman-active and recognition molecule. 4-MPBA provides a unique interactive boronic acid group to the diol group of TYR substrate and exhibits good SERS signal. Also, the introduction of magnetic beads could promptly improve the anti-interference ability of dual-mode sensor. The TYR-incubated tyramine-modified magnetic beads could obviously change the concentration of 4-MPBA-AuNPs in the presence of O2 and ascorbic acid, where the ultraviolet visible (UV–vis) absorption and SERS intensity were directly related to the concentration of TYR added. The dual-mode sensor had a rapid response to TYR within 1 min under optimized conditions and had high selectivity for TYR with a limit of detection at 0.001 U/mL. In addition, the dual-mode strategy showed promising prospects in the determination of TYR activity in serum samples and could be used to screen TYR inhibitors.

Glycosyl imprinted mesoporous microspheres for the determination of glycopeptide antibiotics using ultra-high performance liquid chromatography coupled with tandem mass spectrometry

Glycopeptide antibiotics are critical weapons against serious Gram-positive resistant bacteria, and therefore the development of analytical methods for their determination is essential. In this work, with the aim of extending the scope of molecularly imprinted mesoporous materials to the recognition of large molecules such as proteins and peptides, we selected the glycosyl moiety of glycopeptide antibiotics as a template and synthesised a boronic acid functional monomer by click chemistry reaction to prepare glycosyl imprinted mesoporous microspheres. On the basis of boronate affinity, the template and the functional monomer formed a self-assembly structure that was incorporated into the silica framework during polymerisation. The removal of the glycosyl moiety created cavities with boronic acid groups covalently anchored to the pore walls of the glycosyl imprinted mesoporous microspheres. The resultant microspheres showed regular spherical shape, narrow size distribution and porous structure and exhibited high adsorption capability and fast adsorption kinetics. The size exclusion effect of the mesoporous structure prevents large molecules from entering the cavities, while the glycosyl imprinted cavities provide selectivity for glycopeptide antibiotics. The glycosyl imprinted mesoporous microspheres were employed to separate six glycopeptide antibiotics in serum samples, which were then determined using ultra-high performance liquid chromatography tandem mass spectrometry. The proposed method exhibited satisfactory linearity in the range of 0.1 to 20.0 μg/L, demonstrating great potential for the determination of glycopeptide antibiotics in serum samples.