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Pyrazolo[3,4-b]pyridine scaffolds have been heavily exploited in the development of nitrogen-containing heterocycles with numerous therapeutic applications in the field of medicinal and pharmaceutical chemistry. The present work describes the synthesis of eighteen biaryl pyrazolo[3,4-b]pyridine ester (6a–i) and hydrazide (7a–i) derivatives via the Suzuki cross-coupling reaction. These derivatives were subsequently screened for their therapeutic potential to inhibit the diabetic α-amylase enzyme, which is a key facet of the development of anti-diabetic agents. Initially, the ethyl 4-(4-bromophenyl)-3-methyl-1-phenyl-1H-pyrazolo[3,4-b]pyridine-6-carboxylate 4 was synthesized through a modified Doebner method under solvent-free conditions, providing an intermediate for further derivatization with a 60% yield. This intermediate 4 was subjected to Suzuki cross-coupling, reacting with electronically diverse aryl boronic acids to obtain the corresponding pyrazolo[3,4-b]pyridine ester derivatives (6a–i). Following this, the biaryl ester derivatives (6a–i) were converted into hydrazide derivatives (7a–i) through a straightforward reaction with hydrazine monohydrate and were characterized using 1H-NMR, 13C-NMR, and LC-MS spectroscopic techniques. These derivatives were screened for their α-amylase inhibitory chemotherapeutic efficacy, and most of the biaryl ester and hydrazide derivatives demonstrated promising amylase inhibition. In the (6a–i) series, the compounds 6b, 6c, 6h, and 6g exhibited excellent inhibition, with almost similar IC50 values of 5.14, 5.15, 5.56, and 5.20 μM, respectively. Similarly, in the series (7a–i), the derivatives 7a, 7b, 7c, 7d, 7f, 7g, and 7h displayed excellent anti-diabetic activities of 5.21, 5.18, 5.17, 5.12, 5.10, 5.16, and 5.19 μM, respectively. These in vitro results were compared with the reference drug acarbose (IC50 = 200.1 ± 0.15 μM), demonstrating better anti-diabetic inhibitory activity in comparison to the reference drug. The in silico molecular docking study results were consistent with the experimental biological findings, thereby supporting the in vitro pharmaceutical efficacy of the synthesized derivatives. [ABSTRACT FROM AUTHOR]

Incorporating nanoparticles into injectable hydrogels is a well-known technique for improving the mechanical properties of these materials. However, significant differences in the mechanical properties of the polymer matrix and the nanoparticles can result in localized stress concentrations at the polymer–nanoparticle interface. This situation can lead to problems such as particle–matrix debonding, void formation, and material failure. This work introduces boronic acid/boronate ester dynamic covalent bonds (DCBs) as energy dissipation sites to mitigate stress concentrations at the polymer–nanoparticle interface. Once boronic acid groups were immobilized on the surface of SiO2 nanoparticles (SiO2-BA) and incorporated into an alginate matrix, the nanocomposite hydrogels exhibited enhanced viscoelastic properties. Compared to unmodified SiO2 nanoparticles, introducing SiO2 nanoparticles with boronic acid on their surface improved the structural integrity and stability of the hydrogel. In addition, nanoparticle-reinforced hydrogels showed increased stiffness and deformation resistance compared to controls. These properties were dependent on nanoparticle concentration. Injectability tests showed shear-thinning behavior for the modified hydrogels with injection force within clinically acceptable ranges and superior recovery. [ABSTRACT FROM AUTHOR]

The general synthesis of boron-containing cyclic compounds (boracycles) necessitates toxic organotin precursors or highly reactive boron halides. Here, we report the synthesis of seven- and five-membered boracycles utilizing arylboronic acid pinacol esters (ArBpins) as stable boron sources. Grignard reagents generated from 2,2′-dibromodibenzyl or 2,2′-dibromobiphenyl reacted with ArBpins, where Ar = 9-anthryl (Anth), 2,4,6-trimethylphenyl (Mes), or 2,4,6-triisopropylphenyl (Tip), to give 10,11-dihydro-5H-dibenzo[b,f]borepins or dibenzoborole derivatives. This Bpin-based method was successfully applied to a one-shot double boracycle formation, providing a dihydrodibenzoborepin–anthracene–dihydrodibenzoborepin triad molecule in a good yield. The dihydrodibenzoborepin bearing the Anth group was directly converted to the unsaturated borepin by NBS/AIBN. All products were characterized by NMR, HRMS, and in some cases, single-crystal X-ray diffraction analysis. Additionally, the photophysical properties of the products are also reported. [ABSTRACT FROM AUTHOR]

Saccharides, being one of the fundamental molecules of life, play essential roles in the physiological and pathological functions of cells. However, their intricate structures pose challenges for detection. Nanopore technology, with its high sensitivity and capability for single-molecule-level analysis, has revolutionized the identification and structural analysis of saccharide molecules. This review focuses on recent advancements in nanopore technology for carbohydrate detection, presenting an array of methods that leverage the molecular complexity of saccharides. Biological nanopore techniques utilize specific protein binding or pore modifications to trigger typical resistive pulses, enabling the high-sensitivity detection of monosaccharides and oligosaccharides. In solid-state nanopore sensing, boronic acid modification and pH gating mechanisms are employed for the specific recognition and quantitative analysis of polysaccharides. The integration of artificial intelligence algorithms can further enhance the accuracy and reliability of analyses. Serving as a crucial tool in carbohydrate detection, we foresee significant potential in the application of nanopore technology for the detection of carbohydrate molecules in disease diagnosis, drug screening, and biosensing, fostering innovative progress in related research domains. [ABSTRACT FROM AUTHOR]

Opportunistic bacterial pathogens can evade the immune response by residing and reproducing within host immune cells, including macrophages. These intracellular infections provide reservoirs for pathogens that enhance the progression of infections and inhibit therapeutic strategies. Current sensing strategies for intracellular infections generally use immunosensing of specific biomarkers on the cell surface or polymerase chain reaction (PCR) of the corresponding nucleic acids, making detection difficult, time-consuming, and challenging to generalize. Intracellular infections can induce changes in macrophage glycosylation, providing a potential strategy for signature-based detection of intracellular infections. We report here the detection of bacterial infection in macrophages using a boronic acid (BA)-based pH-responsive polymer sensor array engineered to distinguish mammalian cell phenotypes by their cell surface glycosylation signatures. The sensor was able to discriminate between different infecting bacteria in minutes, providing a promising tool for diagnostic and screening applications. [ABSTRACT FROM AUTHOR]

Novel fluorescent pyrazole-containing boron (III) complexes were synthesized employing a one-pot three-component reaction of 3-hydroxy-1-phenyl-1H-pyrazole-4-carbaldehyde, 2-aminobenzenecarboxylic acids, and boronic acids. The structures of the novel heterocyclic compounds were confirmed using 1H-, 13C-, 15N-, 19F-, and 11B-NMR, IR spectroscopy, HRMS, and single-crystal X-ray diffraction data. The photophysical properties of the obtained iminoboronates were investigated using spectroscopic techniques, such as UV–vis and fluorescence spectroscopies. Compounds display main UV–vis absorption maxima in the blue region, and fluorescence emission maxima are observed in the green region of the visible spectrum. It was revealed that compounds exhibit fluorescence quantum yield up to 4.3% in different solvents and demonstrate an aggregation-induced emission enhancement effect in mixed THF–water solutions. [ABSTRACT FROM AUTHOR]

Boronic acids form diester bonds with cis-hydroxyl groups in carbohydrates. The formation of these adducts could impair the physical and chemical properties of precursors, even their biological activity. Two carbohydrate derivatives from d-fructose and d-arabinose and phenylboronic acid were synthesized in a straightforward one-step procedure and chemically characterized via spectroscopy and X-ray diffraction crystallography. Additionally, an acute toxicity test was performed to determine their lethal dose 50 (LD50) values by using Lorke's method. Analytical chemistry assays confirmed the formation of adducts by the generation of diester bonds with the β-d-pyranose of carbohydrates, including signals corresponding to the formation of new bonds, such as the stretching of B–O bonds. NMR spectra yielded information about the stereoselectivity in the synthesis reaction: Just one signal was found in the range for the anomeric carbon in the 13C NMR spectra of both adducts. The acute toxicity tests showed that the LD50 value for both compounds was 1265 mg/kg, while the effective dose 50 (ED50) for sedation was 531 mg/kg. However, differences were found in the onset and lapse of sedation. For example, the arabinose derivative induced sedation for more than 48 h at 600 mg/kg, while the fructose derivative induced sedation for less than 6 h at the same dose without the death of the mice. Thus, we report for the first time two boron-containing carbohydrate derivatives inducing sedation after intraperitoneal administration. They are bioactive and highly safe agents. Further biological evaluation is desirable to explore their medical applications. [ABSTRACT FROM AUTHOR]

The wide use of boronic compounds, especially boronic acids and benzoxaboroles, in virtually all fields of chemistry is related to their specific properties. The most important of them are the ability to form cyclic esters with diols and the complexation of anions. In both cases, the equilibrium of the reaction depends mainly on the acidity of the compounds, although other factors must also be taken into account. Quantification of the acidity (pKa value) is a fundamental factor considered when designing new compounds of practical importance. The aim of the current work was to collect available values of the acidity constants of monosubstituted phenylboronic acids, critically evaluate these data, and supplement the database with data for missing compounds. Measurements were made using various methods, as a result of which a fast and reliable method for determining the pKa of boronic compounds was selected. For an extensive database of monosubstituted phenylboronic acids, their correlation with their Brønsted analogues—namely carboxylic acids—was examined. Compounds with ortho substituents do not show any correlation, which is due to the different natures of both types of acids. Nonetheless, both meta- and para-substituted compounds show excellent correlation. From a practical point of view, acidity constants are best determined from the Hammett equation. Computational approaches for determining acidity constants were also analyzed. In general, the reported calculated values are not compatible with experimental ones, providing comparable results only for selected groups of compounds. [ABSTRACT FROM AUTHOR]

High-performance electrochromic (EC) and electrofluorochromic (EFC) materials have garnered considerable interest due to their diverse applications in smart windows, optoelectronics, optical displays, military camouflage, etc. While many different EC and EFC polymers have been reported, their preparation often requires multiple steps, and their polymer molecular weights are subjected to batch variation. In this work, we prepared two triphenylamine (TPA)-based and two tetraphenylethylene (TPE)-based derivatives functionalized with terminal styryl groups via direct Suzuki coupling with (4-vinylphenyl)boronic acid and vinylboronic acid pinacol ester. The two novel TPE derivatives exhibited green–yellow aggregation-induced emission (AIE). The EC and EFC properties of pre- and post-thermally treated derivatives spin-coated onto ITO–glass substrates were studied. While all four derivatives showed modest absorption changes with applied voltages up to +2.4 V, retaining a high degree of optical transparency, they exhibited obvious EFC properties with the quenching of blue to yellow fluorescence with IOFF/ON contrast ratios of up to 7.0. The findings therefore demonstrate an elegant approach to preparing optically transparent, heat-induced, cross-linkable styryl-functionalized EFC systems. [ABSTRACT FROM AUTHOR]

In this article, we report a very efficient method for the determination of the enantiopurity of 1,2-diacyl-sn-glycero-3-phosphocholine by 1H NMR analysis using a readily available chiral derivatizing boronic acid (CDA), (R)-(2-(((1-phenylethyl)amino)methyl)phenyl)boronic acid. After the removal of the acyl groups of 1,2-diacyl-sn-glycero-3-phosphocholine via methanolysis and washing fatty acid byproducts with CHCl3, the obtained sn-glycero-3-phosphocholine (GPC) with the free diol moiety is derivatized by the chiral boronic acid and analyzed by 1H NMR analysis. The choline methyl resonance of each diastereomer is observed at distinctive chemical shifts in the 1H NMR spectrum. Integration of the respective resonances allows direct determination of the enantiomeric purity. The procedure was tested successfully using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) with different enantiomeric purities and with commercially available 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC). [ABSTRACT FROM AUTHOR]

The reversibility of the covalent interaction between boronic acids and 1,2- or 1,3-diols has put the spotlight on this reaction for its potential in the development of sensors and for the fishing of bioactive glycoconjugates. In this work, we describe the investigation of this reaction for the reversible functionalization of the surface of CdSe/ZnS Quantum Rods (QRs). With this in mind, we have designed a turn-off Förster resonance energy transfer (FRET) system that ensures monitoring the extent of the reaction between the phenyl boronic residue at the meso position of a BODIPY probe and the solvent-exposed 1,2-diols on QRs' surface. The reversibility of the corresponding boronate ester under oxidant conditions has also been assessed, thus envisioning the potential sensing ability of this system. [ABSTRACT FROM AUTHOR]

This editorial provides an overview of a special issue titled "State of the Art in Molecular Catalysis in Europe" in the journal Catalysts. The issue includes eleven contributions covering a wide range of topics related to heterogeneous and homogeneous catalysis. Two reviews discuss the catalytic aspects of Zn-air batteries and organic dyes, while the remaining nine scientific research papers focus on topics such as palladium catalysts, acid hydrolysis/dehydration, and catalysts for polymerization processes. The authors express their gratitude to the contributors and hope that readers will enjoy the special issue. [Extracted from the article]

An overexpression of sialic acid is an indicator of metastatic cancer, and selective detection of sialic acid shows potential for cancer diagnosis. Boronic acid is a promising candidate for this purpose because of its ability to specifically bind to sialic acid under acidic conditions. Notably, the binding strength can be easily modulated by adjusting the pH, which allows for a simple dissociation of the bound sialic acid. In this study, we developed 5-boronopicolinic acid (5-BPA)-modified magnetic particles (BMPs) to selectively capture sialic acid biomolecules. We successfully captured fetuin, a well-known sialoglycoprotein, on BMPs at >104 molecules/particle using an acetate buffer (pH 5.0). Facile dissociation then occurred when the system was changed to a pH 7.6 phosphate buffer. This capture-and-release process could be repeated at least five times. Moreover, this system could enrich fetuin by more than 20 times. In summary, BMPs are functional particles for facile purification and concentration through the selective capture of sialic acid proteins and can improve detection sensitivity compared with conventional methods. This technology shows potential for the detection of sialic acid overexpression by biological particles. [ABSTRACT FROM AUTHOR]

Promoting the uptake of dyes is an important part of the sustainable processing of wool products. This study presents an effective modification approach to enhance the dyeability of wool fabric with adenosine triphosphate as an activator, 3-carboxyphenyl boronic acid as a ligand-binding agent, and chitin whisker as a couple agent. The structure and surface morphology of the as-prepared wool fabric was characterized in detail. Natural luteolin and acid red 1 were used to dye the modified wool fabric, and the effect of different dyeing parameters on dyeing properties was discussed. The results indicated that the modified wool gained better surface color depth (K/S) and uptake without additional agents than the untreated wool fabric. When the modified wool fabric was dyed at 45 °C with luteolin and at 60 °C with acid red 1, the dyeing processes of the two dyes on the modified wool fabrics followed the Langmuir isotherm and the pseudo-second-order kinetic model. Furthermore, the dyed modified wool fabrics possessed improved color fastness. Overall, this work offers a facile, effective, and sustainable way to improve the low-temperature dyeability of wool products. [ABSTRACT FROM AUTHOR]

We have designed and synthesized a series of bioinspired pyrano[2,3-f]coumarin-based Calanolide A analogs with anti-HIV activity. The design of these new calanolide analogs involved incorporating nitrogen heterocycles or aromatic groups in lieu of ring C, effectively mimicking and preserving their bioactive properties. Three directions for the synthesis were explored: reaction of 5-hydroxy-2,2-dimethyl-10-propyl-2H,8H-pyrano[2,3-f]chromen-8-one with (i) 1,2,4-triazines, (ii) sulfonylation followed by Suzuki cross-coupling with (het)aryl boronic acids, and (iii) aminomethylation by Mannich reaction. Antiviral assay of the synthesized compounds showed that compound 4 has moderate activity against HIV-1 on enzymes and poor activity on the cell model. A molecular docking study demonstrates a good correlation between in silico and in vitro HIV-1 reverse transcriptase (RT) activity of the compounds when docked to the nonnucleoside RT inhibitor binding site, and alternative binding modes of the considered analogs of Calanolide A were established. [ABSTRACT FROM AUTHOR]

The complexation of boric acid (BA) with various α-hydroxycarboxylic acids (HCAs) was examined by analyzing the change in the optical rotation after the addition of BA to aqueous HCA solutions, and the catalytic properties of the complexes were examined by catalyzing the esterification of the HCAs. The absolute values of the optical rotation of the HCAs increased with increasing BA-to-HCA molar ratio, and the rate of change of the optical rotation gradually decreased as the BA-to-HCA molar ratio increased, reaching a minimum value at a molar ratio of approximately three. As a catalyst, BA could catalyze the acetylation of hydroxyl groups in addition to the esterification of HCAs. Compared to the conventional synthesis routes of ATBC and ATOC, a synthesis route with BA as the catalyst allowed for a lower frequency of catalyst separation and replacement while providing light-colored products. BA could catalyze the formation of triethyl citrate, and the yield of triethyl citrate reached 93.8%. BA could also catalyze the reaction between malic acid and pinene to produce borneol malate. After saponification of borneol malate, borneol was obtained with a yield of 39%. [ABSTRACT FROM AUTHOR]

The Petasis reaction, also called the Petasis Borono–Mannich reaction, is a multicomponent reaction that couples a carbonyl derivative, an amine and boronic acids to yield substituted amines. The reaction proceeds efficiently in the presence or absence of a specific catalyst and solvent. By employing this reaction, a diverse range of chiral derivatives can easily be obtained, including α-amino acids. A broad substrate scope, high yields, distinct functional group tolerance and the availability of diverse catalytic systems constitute key features of this reaction. In this review article, attention has been drawn toward the recently reported methodologies for executing the Petasis reaction to produce structurally simple to complex aryl/allyl amino scaffolds. [ABSTRACT FROM AUTHOR]

Double crosslinked hydrogels based on a biodegradable polymer were prepared by photocopolymerization of methacrylated hydroxypropyl guar (HPG-MA) and 3-acrylamidophenylboronic acid. Along with irreversible strong covalent crosslinks by methacrylic groups, these hydrogels contained labile boronate crosslinks formed as a result of the interaction of boronic acid with cis-diol moieties of HPG. These hydrogels demonstrated higher elasticity than HPG-MA hydrogels with only irreversible covalent crosslinks. Labile boronate crosslinks not only strengthened the hydrogels but also imparted to them pronounced responsive properties. It was demonstrated that the mechanical properties, the swelling behavior, as well as the uptake and release of some substances from the double crosslinked hydrogel were pH controlled. For instance, the hydrogels could release cationic disinfectant at a rate regulated by pH. Such photocrosslinkable in situ forming hydrogels are very promising for the production of smart coatings that release targeted substances at the desired rate. [ABSTRACT FROM AUTHOR]

Interest in the design of boronated amino acids has emerged, partly due to the utilization of boronophenylalanine (BPA), one of the two agents employed in clinical Boron Neutron Capture Therapy (BNCT). The boronated amino acids synthesized thus far for BNCT investigations can be classified into two categories based on the source of boron: boronic acids or carboranes. Amino acid-based boron carriers, employed in the context of BNCT treatment, demonstrate significant potential in the treatment of challenging tumors, such as those located in the brain. This review aims to shed light on the developmental journey and challenges encountered over the years in the field of amino acid-based boron delivery compound development. The primary focus centers on the utilization of the large amino acid transporter 1 (LAT1) as a target for boron carriers in BNCT. The development of efficient carriers remains a critical objective, addressing challenges related to tumor specificity, effective boron delivery, and rapid clearance from normal tissue and blood. LAT1 presents an intriguing and promising target for boron delivery, given its numerous characteristics that make it well suited for drug delivery into tumor tissues, particularly in the case of brain tumors. [ABSTRACT FROM AUTHOR]

The C-3 modification of 1H-indazole has produced active pharmaceuticals for the treatment of cancer and HIV. But, so far, this transformation has seemed less available, due to the lack of efficient C-C bond formation at the less reactive C-3 position. In this work, a series of silica gel-supported PdO2 nanoparticles of 25–66 nm size were prepared by ball milling silica gel with divalent palladium precursors, and then employed as catalysts for the Suzuki–Miyaura cross-coupling of 1H-indazole derivative with phenylboronic acid. All the synthesized catalysts showed much higher cross-coupling yields than their palladium precursors, and could also be reused three times without losing high activity and selectivity in a toluene/water/ethanol mixed solvent. Although the palladium precursors showed an order of activity of PdCl2(dppf, 1,1′-bis(diphenylphosphino)ferrocene) > PdCl2(dtbpf, 1,1′-bis(di-tert-butylphosphino)ferrocene) > Pd(OAc, acetate)2, the synthesized catalysts showed an order of C1 (from Pd(OAc)2) > C3 (from PdCl2(dtbpf)) > C2 (from PdCl2(dppf)), which conformed to the orders of BET (Brunauer–Emmett–Teller) surface areas and acidities of these catalysts. Notably, the most inexpensive Pd(OAc)2 can be used as a palladium precursor for the synthesis of the best catalyst through simple ball milling. This work provides a highly active and inexpensive series of catalysts for C-3 modification of 1H-indazole, which are significant for the large-scale production of 1H-indazole-based pharmaceuticals. [ABSTRACT FROM AUTHOR]

An efficient method for the synthesis of 2-ethylhexanoic acid has been reported. The method involves the 2-ethylhexanal oxidation using oxygen or air in the presence of N-hydroxyphthalimide in isobutanol as a solvent under mild conditions. A high selectivity of >99% for 2-ethylhexanoic acid was achieved. The influence of catalyst amount, solvent type and quantity, temperature, and reaction time on the product composition was studied. The developed method is in line with the global trends aimed at developing green oxidation processes as well as having potential for implementation in industry due to its high selectivity, cost-effective oxidizing agent, and mild reaction conditions. The use of isobutanol as a solvent is of crucial importance providing an opportunity for potential producers of 2-EHAL from butanal to employ the less valuable alcohol. [ABSTRACT FROM AUTHOR]

Thermosetting adhesives are commonly utilized in various applications. However, covalent cross-linked networks prevent thermosetting adhesives from being re-assembled, which necessitates higher machining precision. Additionally, the primary raw materials used in adhesive preparation are derived from non-renewable petroleum resources, which further constrain adhesive development. In this study, a recyclable adhesive was developed by incorporating dynamic boronic esters into epoxy resin derived from soybean oil. The successful synthesis of epoxidized soybean oil and boronic esters was confirmed through the analysis of proton nuclear magnetic resonance spectra and differential scanning calorimetry results. Swelling tests and tensile curves demonstrated the presence of covalently cross-linked networks. Self-healing and reprocessing experiments indicated that the cross-linked network topology could be re-assembled under mild conditions. [ABSTRACT FROM AUTHOR]

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

The new Lewis acid–base adducts of general formula X(nad)B←NC5H4-C5H4N→B(nad)X [nad = 1,8-O2C10H6, X = C6H5 (2c), 3,4,5-F3-C6H2 (2d)] were synthesized in high yields via reactions of 1,8-dihydroxy naphthalene [nadH2] and 4,4′-bipyridine with the aryl boronic acids C6H5B(OH)2 and 3,4,5-F3-C6H2B(OH)2, respectively, and structurally characterized by multi-nuclear NMR spectroscopy and SCXRD. Self-assembled H-shaped Lewis acid–base adduct 2d proved to be effective in forming thermally stable host–guest complexes, 2d × solvent, with aromatic hydrocarbon solvents such as benzene, toluene, mesitylene, aniline, and m-, p-, and o-xylene. Crystallographic analysis of these solvent adducts revealed host–guest interactions to primarily occur via π···π contacts between the 4,4′-bipyridyl linker and the aromatic solvents, resulting in the formation of 1:1 and 1:2 host–guest complexes. Thermogravimetric analysis of the isolated complexes 2d × solvent revealed their high thermal stability with peak temperatures associated with the loss of solvent ranging from 122 to 147 °C. 2d, when self-assembled in an equimolar mixture of m-, p-, and o-xylene (1:1:1), preferentially binds to o-xylene. Collectively, these results demonstrate the ability of 1,8-dihydroxy naphthalene to serve as an effective building block in the selective self-assembly to supramolecular aggregates through dative covalent N→B bonds. [ABSTRACT FROM AUTHOR]

Pyranoquinolinones synthesized from citral were used for Cu-catalyzed N-arylation with a wide range of arylboric acids. The reaction proceeded well with a broad substrate scope, providing a direct way to access highly functional pyranoquinolinone core structure derivatives in yields of up to 80%. Compared to citral, the compounds we obtained have a much better inhibitory effect on HeLa cervical cancer cells, and compound 3p has an IC50 value of 4.6 μM, lower than cisplatin's 5.9 μM. [ABSTRACT FROM AUTHOR]

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

Modification of 5-aryl-4-trifluoroacetyltriazoles at the NH-moiety was investigated. Screening of the alkylation conditions revealed that using Na2CO3 as a base and DMF as a solvent of 2-substituted triazoles can be preferentially prepared in up to 86% yield. In the best cases, the amount of minor 1-alkyl isomer was less than 6%. SNAr reaction of the 5-aryl-4-trifluoroacetyltriazoles with aryl halides having electron-withdrawing groups led to regiospecific formation of 2-aryltriazoles isolated in good-to-high yields. Chan–Lam reaction of the 5-aryl-4-trifluoroacetyltriazoles with boronic acids afforded 2-aryltriazoles as single isomers in up to 89% yield. The subsequent reaction of the prepared 2-aryltriazoles with primary and secondary amines gave a set of amides of 4-(2,5-diaryltriazolyl)carboxylic acid. The fluorescent properties of the prepared 2-substituted derivatives of triazoles were investigated to demonstrate their utility as new efficient luminophores having more than 60% quantum yields. [ABSTRACT FROM AUTHOR]

Fibroblast activation protein (FAP) is a membrane-tethered serine protease overexpressed in the reactive stromal fibroblasts of >90% human carcinomas, which makes it a promising target for developing radiopharmaceuticals for the imaging and therapy of carcinomas. Here, we synthesized two novel (R)-pyrrolidin-2-yl-boronic acid-based FAP-targeted ligands: SB02055 (DOTA-conjugated (R)-(1-((6-(3-(piperazin-1-yl)propoxy)quinoline-4-carbonyl)glycyl)pyrrolidin-2-yl)boronic acid) and SB04028 (DOTA-conjugated ((R)-1-((6-(3-(piperazin-1-yl)propoxy)quinoline-4-carbonyl)-D-alanyl)pyrrolidin-2-yl)boronic acid). natGa- and 68Ga-complexes of both ligands were evaluated in preclinical studies and compared to previously reported natGa/68Ga-complexed PNT6555. Enzymatic assays showed that FAP binding affinities (IC50) of natGa-SB02055, natGa-SB04028 and natGa-PNT6555 were 0.41 ± 0.06, 13.9 ± 1.29 and 78.1 ± 4.59 nM, respectively. PET imaging and biodistribution studies in HEK293T:hFAP tumor-bearing mice showed that while [68Ga]Ga-SB02055 presented with a nominal tumor uptake (1.08 ± 0.37 %ID/g), [68Ga]Ga-SB04028 demonstrated clear tumor visualization with ~1.5-fold higher tumor uptake (10.1 ± 0.42 %ID/g) compared to [68Ga]Ga-PNT6555 (6.38 ± 0.45 %ID/g). High accumulation in the bladder indicated renal excretion of all three tracers. [68Ga]Ga-SB04028 displayed a low background level uptake in most normal organs, and comparable to [68Ga]Ga-PNT6555. However, since its tumor uptake was considerably higher than [68Ga]Ga-PNT6555, the corresponding tumor-to-organ uptake ratios for [68Ga]Ga-SB04028 were also significantly greater than [68Ga]Ga-PNT6555. Our data demonstrate that (R)-(((quinoline-4-carbonyl)-d-alanyl)pyrrolidin-2-yl)boronic acid is a promising pharmacophore for the design of FAP-targeted radiopharmaceuticals for cancer imaging and radioligand therapy. [ABSTRACT FROM AUTHOR]

Chemotherapy is currently one of the most widely used treatments for cancer. However, traditional chemotherapy drugs normally have poor tumor selectivity, leading to insufficient accumulation at the tumor site and high systemic cytotoxicity. To address this issue, we designed and prepared a boronic acid/ester-based pH-responsive nano-drug delivery system that targets the acidic microenvironment of tumors. We synthesized hydrophobic polyesters with multiple pendent phenylboronic acid groups (PBA-PAL) and hydrophilic PEGs terminated with dopamine (mPEG-DA). These two types of polymers formed amphiphilic structures through phenylboronic ester linkages, which self-assembled to form stable PTX-loaded nanoparticles (PTX/PBA NPs) using the nanoprecipitation method. The resulting PTX/PBA NPs demonstrated excellent drug encapsulation efficiency and pH-triggered drug-release capacity. In vitro and in vivo evaluations of the anticancer activity of PTX/PBA NPs showed that they improved the pharmacokinetics of drugs and exhibited high anticancer activity while with low systemic toxicity. This novel phenylboronic acid/ester-based pH-responsive nano-drug delivery system can enhance the therapeutic effect of anticancer drugs and may have high potential for clinical transformations. [ABSTRACT FROM AUTHOR]

The Petasis borono-Mannich reaction, commonly described as the Petasis reaction, was one of the latest famous multicomponent reactions described in the literature. Currently celebrating its 30th anniversary since it was first reported by Petasis and Akritopoulou in 1993, this reaction has emerged as a powerful tool for the synthesis of biologically relevant molecules (such as substituted amines or amino acids), among others. This three-component catalyst-free reaction (the classic model), involving the coupling of an aldehyde, an amine, and a boronic acid, enables the synthesis of polysubstituted amine-containing molecules. Several accounts regarding the catalyst-free version using different carbonyl, amine, and boron-type components have been reported thus far. In contrast, the asymmetric version is still in its infancy since it was first reported in 2007. In this work, we aim to review the asymmetric versions of the Petasis reaction reported over the last 15 years, considering the chiral pool approach (asymmetric induction by one reaction component) and the use of catalysts (organocatalysts, transition-metal catalysts, and others) to access enantiomeric and diastereomeric pure amino-derivatives. Insights regarding the catalyzed Petasis reaction and consequent sustainable synthesis will be highlighted. [ABSTRACT FROM AUTHOR]

A systematic synthetic study was performed to explain the usual trend in selectivity towards multi-coupling, over mono-coupling, in Suzuki–Miyaura reactions. This preference was observed under different reaction conditions: for various halobenzenes, using substituents on the boronic acid, and changing the catalyst and temperature. Moreover, this reaction selectivity was found to increase for more reactive systems towards oxidative addition and more diluted media. The results constitute experimental evidence that the formation of the totally substituted coupling product is kinetically favoured by a reaction path location—the proximity between the regenerated catalyst and the newly formed coupling intermediate promotes the subsequent reaction. [ABSTRACT FROM AUTHOR]

Non-enzymatic sensors with the capability of long-term stability and low cost are promising in glucose monitoring applications. Boronic acid (BA) derivatives offer a reversible and covalent binding mechanism for glucose recognition, which enables continuous glucose monitoring and responsive insulin release. To improve selectivity to glucose, a diboronic acid (DBA) structure design has been explored and has become a hot research topic for real-time glucose sensing in recent decades. This paper reviews the glucose recognition mechanism of boronic acids and discusses different glucose sensing strategies based on DBA-derivatives-based sensors reported in the past 10 years. The tunable pKa, electron-withdrawing properties, and modifiable group of phenylboronic acids were explored to develop various sensing strategies, including optical, electrochemical, and other methods. However, compared to the numerous monoboronic acid molecules and methods developed for glucose monitoring, the diversity of DBA molecules and applied sensing strategies remains limited. The challenges and opportunities are also highlighted for the future of glucose sensing strategies, which need to consider practicability, advanced medical equipment fitment, patient compliance, as well as better selectivity and tolerance to interferences. [ABSTRACT FROM AUTHOR]

Cold physical plasma is a partially ionized gas operated at body temperature and utilized for heat-sensitive technical and medical purposes. Physical plasma is a multi-component system consisting of, e.g., reactive species, ions and electrons, electric fields, and UV light. Therefore, cold plasma technology is an interesting tool for introducing biomolecule oxidative modifications. This concept can be extended to anticancer drugs, including prodrugs, which could be activated in situ to enhance local anticancer effects. To this end, we performed a proof-of-concept study on the oxidative prodrug activation of a tailor-made boronic pinacol ester fenretinide treated with the atmospheric pressure argon plasma jet kINPen operated with either argon, argon–hydrogen, or argon–oxygen feed gas. Fenretinide release from the prodrug was triggered via Baeyer–Villiger-type oxidation of the boron–carbon bond based on hydrogen peroxide and peroxynitrite, which were generated by plasma processes and chemical addition using mass spectrometry. Fenretinide activation led to additive cytotoxic effects in three epithelial cell lines in vitro compared to the effects of cold plasma treatment alone regarding metabolic activity reduction and an increase in terminal cell death, suggesting that cold physical plasma-mediated prodrug activation is a new direction for combination cancer treatment studies. [ABSTRACT FROM AUTHOR]

Methacrolein (MAL) is an important intermediate extensively used in the manufacture of methyl methacrylate and other materials (polymers and resins). In this study, a series of secondary amines/acids were explored as catalysts for the condensation of formaldehyde and propionaldehyde to prepare MAL. It was found that the structure of the amines and acids directly affected the yield of MAL. The effect of the catalyst was closely related to the nucleophilicity of the amines as well as the steric hindrance effect, while acids also played a role as co-catalysts. Dibutylamine acetate was selected as the catalyst after investigation. The catalytic performance of the system was systematically studied by a series of single-factor experiments, including stirring rate, temperature, reaction time, acid/amine ratio, and the solvent, and the optimized reaction conditions were obtained. In the optimum condition, the yield of MAL was up to 97.3%. Kinetic experiments were performed for the condensation of formaldehyde and propionaldehyde to MAL, and the activation energies, reaction orders, and rate-limiting step of the reaction were determined. The results indicate that the decomposition of the Mannich base is a rate-limiting step. [ABSTRACT FROM AUTHOR]

Molecular immobilization and recognition are two key events for the development of biosensors. The general ways for the immobilization and recognition of biomolecules include covalent coupling reactions and non-covalent interactions of antigen–antibody, aptamer–target, glycan–lectin, avidin–biotin and boronic acid–diol. Tetradentate nitrilotriacetic acid (NTA) is one of the most common commercial ligands for chelating metal ions. The NTA–metal complexes show high and specific affinity toward hexahistidine tags. Such metal complexes have been widely utilized in protein separation and immobilization for diagnostic applications since most of commercialized proteins have been integrated with hexahistidine tags by synthetic or recombinant techniques. This review focused on the development of biosensors with NTA–metal complexes as the binding units, mainly including surface plasmon resonance, electrochemistry, fluorescence, colorimetry, surface-enhanced Raman scattering spectroscopy, chemiluminescence and so on. [ABSTRACT FROM AUTHOR]

A heterostructured nanocomposite MCM-41 was formed using the encapsulation method, where a silicon dioxide matrix—MCM-41 was the host matrix and synthetic fulvic acid was the organic guest. Using the method of nitrogen sorption/desorption, a high degree of monoporosity in the studied matrix was established, with a maximum for the distribution of its pores with radii of 1.42 nm. According to the results of an X-ray structural analysis, both the matrix and the encapsulate were characterized by an amorphous structure, and the absence of a manifestation of the guest component could be caused by its nanodispersity. The electrical, conductive, and polarization properties of the encapsulate were studied with impedance spectroscopy. The nature of the changes in the frequency behavior of the impedance, dielectric permittivity, and tangent of the dielectric loss angle under normal conditions, in a constant magnetic field, and under illumination, was established. The obtained results indicated the manifestation of photo- and magneto-resistive and capacitive effects. In the studied encapsulate, the combination of a high value of ε and a value of the tgδ of less than 1 in the low-frequency range was achieved, which is a prerequisite for the realization of a quantum electric energy storage device. A confirmation of the possibility of accumulating an electric charge was obtained by measuring the I-V characteristic, which took on a hysteresis behavior. [ABSTRACT FROM AUTHOR]

It has been demonstrated that different organoboron compounds interact with some well-known molecular targets, including serine proteases, transcription factors, receptors, and other important molecules. Several approaches to finding the possible beneficial effects of boronic compounds include various in silico tools. This work aimed to find the most probable targets for five aromatic boronic acid derivatives. In silico servers, SuperPred, PASS-Targets, and Polypharmacology browser 2 (PPB2) suggested that the analyzed compounds have anticancer properties. Based on these results, the antiproliferative effect was evaluated using an in vitro model of triple-negative breast cancer (4T1 cells in culture). It was demonstrated that phenanthren-9-yl boronic acid and 6-hydroxynaphthalen-2-yl boronic acid have cytotoxic properties at sub-micromolar concentrations. In conclusion, using in silico approaches and in vitro analysis, we found two boronic acid derivatives with potential anticancer activity. [ABSTRACT FROM AUTHOR]

A simple and convenient synthesis of (–)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline-1-carboxylic acid is described, applying a combination of two synthetic methods: the Petasis reaction and Pomeranz–Fritsch–Bobbitt cyclization. The diastereomeric morpholinone derivative N-(2,2-diethoxyethyl)-3-(3,4-dimethoxyphenyl)-5-phenyl-1,4-oxazin-2-one formed in the Petasis reaction was further transformed into 1,2,3,4-tetrahydroisoquinoline-1-carboxylic acid via Pomeranz–Fritsch–Bobbitt cyclization, a classical method of synthesis leading to the tetrahydroisoquinoline core. We review important examples of applications of the Pomeranz–Fritsch process and its modifications in the synthesis of chiral tetrahydroisoquinoline derivatives that have been published in the past two decades. [ABSTRACT FROM AUTHOR]

Acinetobacter baumannii is a Gram-negative organism listed as an urgent threat pathogen by the World Health Organization (WHO). Carbapenem-resistant A. baumannii (CRAB), especially, present therapeutic challenges due to complex mechanisms of resistance to β-lactams. One of the most important mechanisms is the production of β-lactamase enzymes capable of hydrolyzing β-lactam antibiotics. Co-expression of multiple classes of β-lactamases is present in CRAB; therefore, the design and synthesis of "cross-class" inhibitors is an important strategy to preserve the efficacy of currently available antibiotics. To identify new, nonclassical β-lactamase inhibitors, we previously identified a sulfonamidomethaneboronic acid CR167 active against Acinetobacter-derived class C β-lactamases (ADC-7). The compound demonstrated affinity for ADC-7 with a Ki = 160 nM and proved to be able to decrease MIC values of ceftazidime and cefotaxime in different bacterial strains. Herein, we describe the activity of CR167 against other β-lactamases in A. baumannii: the cefepime-hydrolysing class C extended-spectrum β-lactamase (ESAC) ADC-33 and the carbapenem-hydrolyzing OXA-24/40 (class D). These investigations demonstrate CR167 as a valuable cross-class (C and D) inhibitor, and the paper describes our attempts to further improve its activity. Five chiral analogues of CR167 were rationally designed and synthesized. The structures of OXA-24/40 and ADC-33 in complex with CR167 and select chiral analogues were obtained. The structure activity relationships (SARs) are highlighted, offering insights into the main determinants for cross-class C/D inhibitors and impetus for novel drug design. [ABSTRACT FROM AUTHOR]

The C-3 functionalization of 1H-indazole could produce a lot of highly valuable pharmaceutical precursors, which could be used for the treatment of cancer and many other inflammatory diseases. This work was focused on the C-3 functionalization of 1H-indazole through Suzuki–Miyaura cross-coupling of 3-iodo-1H-indazole with organoboronic acids, catalyzed by various palladium catalysts immobilized over imidazolium ionic liquids, as well as catalyst recycling. A series of reaction parameters, including the substrate, catalyst, and ionic liquid, were fully investigated. It is significant to note that the yields of the present Suzuki–Miyaura cross-coupling were mainly determined by the catalyst and the solvent used, more than the chemical structure of the substrate. Furthermore, ferrocene-based divalent palladium complexes showed better catalytic outputs compared to simple palladium salts. Moreover, using two imidazolium ionic liquids, BMImX (BMIm+ = 1-n-butyl-3-methylimidazolium, X− = BF4−, PF6−) not only improved the yields of cross-coupled products, but also avoided the formation of Pd(0) black, as compared to the non-ionic liquid facilitated reactions, and simultaneously making catalyst recycling more effective. On average, BMImBF4 performed better than BMImPF6. Additionally, scientific calculations revealed that 1,1′-bis(diphenylphosphino)ferrocene-palladium(II)dichloride dichloromethane complex (PdCl2(dppf)) showed a lower energy barrier in the formation of intermediates than [1,1′-bis(di-tert-butylphosphino)ferrocene]dichloropalladium(II) (PdCl2(dtbpf)), leading to higher catalytic outputs. This work may contribute to the development of 1H-indazole-derived new pharmaceuticals. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has given a strong impetus to the search for antivirals active on SARS-associated coronaviruses. Over these years, numerous vaccines have been developed and many of these are effective and clinically available. Similarly, small molecules and monoclonal antibodies have also been approved by the FDA and EMA for the treatment of SARS-CoV-2 infection in patients who could develop the severe form of COVID-19. Among the available therapeutic tools, the small molecule nirmatrelvir was approved in 2021. It is a drug capable of binding to the Mpro protease, an enzyme encoded by the viral genome and essential for viral intracellular replication. In this work, by virtual screening of a focused library of β-amido boronic acids, we have designed and synthesized a focused library of compounds. All of them were biophysically tested by microscale thermophoresis, attaining encouraging results. Moreover, they also displayed Mpro protease inhibitory activity, as demonstrated by performing enzymatic assays. We are confident that this study will pave the way for the design of new drugs potentially useful for the treatment of SARS-CoV-2 viral infection. [ABSTRACT FROM AUTHOR]

Background. The global spread of carbapenemase-producing Enterobacterales has become an epidemiological risk for healthcare systems by limiting available antimicrobial treatments. The COVID-19 pandemic worsened this scenario, prompting the emergence of extremely resistant microorganisms. Methods. Between March 2020 and September 2021, the NRL confirmed 82 clinical Enterobacterales isolates harboring a combination of blaKPC and MBL genes. Molecular typing was analyzed by PFGE and MLST. Modified double-disk synergy (MDDS) tests were used for phenotypic studies. Results. Isolates were submitted from 28 hospitals located in seven provinces and Buenos Aires City, including 77 K. pneumoniae, 2 K. oxytoca, 2 C. freundii, and 1 E. coli. Almost half of K. pneumoniae isolates (n = 38; 49.4%), detected in 15 hospitals, belong to the CC307 clone. CC11 was the second clone, including 29 (37.7%) isolates (22, ST11 and 7, ST258) from five cities and 12 hospitals. Three isolates belonging to CC45 were also detected. The carbapenemase combinations observed were as follows: 55% blaKPC-2 plus blaNDM-5; 32.5% blaKPC-2 plus blaNDM-1; 5% blaKPC-3 plus blaNDM-1; 5% blaKPC-2 plus blaIMP-8; and 2.5% strain with blaKPC-2 plus blaNDM-5 plus blaOXA-163. Aztreonam/avibactam and aztreonam/relebactam were the most active combinations (100% and 91% susceptible, respectively), followed by fosfomycin (89%) and tigecycline (84%). Conclusions. The MDDS tests using ceftazidime-avibactam/EDTA and aztreonam/boronic acid disks improved phenotypic classification as dual producers. The successful high-risk clones of K. pneumoniae, such as hyper-epidemic CC307 and CC11 clones, drove the dissemination of double carbapenemase-producing isolates during the COVID-19 pandemic. [ABSTRACT FROM AUTHOR]

Boron-containing compounds (BCC), particularly boronic acids and derivatives, are being increasingly tested as diagnostic and therapeutic agents. Some effects of BCC involve phenomena linked to the action of steroid or thyroid hormones; among these, are the effects on muscle mass or basal metabolism. Additionally, some toxicology reports on mammals, including humans, sound an alert concerning damage to several systems, among which are the negative effects on the induction of male infertility. Systemic and local mechanisms to explain changes in metabolism and impaired fertility were collected and presented. Then, we presented the putative pharmacodynamic and pharmacokinetic mechanisms involved and demonstrated in these events. In addition, it is proposed that there are adducts of some oxygenated BCC with cis-diols in fructose, an essential source of energy for sperm–cell motility, an uncoupling of sex hormone-binding globulin (SHBG) and its ligands, and the modulation of the DNA synthetic rate. These effects share the reactivity of boron-containing compounds on the cis-diols of key molecules. Moreover, data reporting no DNA damage after BCC administration are included. Further studies are required to support the clear role of BCC through these events to disrupt metabolism or fertility in mammals. If such phenomena are confirmed and elucidated, an advance could be useful to design strategies for avoiding BCC toxicity after BCC administration, and possibly for designing metabolism regulators and contraceptive drugs, among other purposes. Boronic derivatives and carboranes have been proposed and studied in this field. [ABSTRACT FROM AUTHOR]

A unique class of β-boron-functionalized non-steroidal anti-inflammatory compound (pinB-NSAID) was previously synthesized via copper-catalyzed 1,2-difunctionalization of the respective vinyl arene with CO2 and B2pin2 reagents. Here, pinacolylboron-functionalized ibuprofen (pinB-ibuprofen) was used as a model substrate to develop the conditions for pinacol deprotection and subsequent boron functionalization. Initial pinacol-boronic ester deprotection was achieved by transesterification with diethanolamine (DEA) from the boralactonate organic salt. The resulting DEA boronate adopts a spirocyclic boralactonate structure rather than a diazaborocane–DABO boronate structure. The subsequent acid-mediated hydrolysis of DEA and transesterification/transamination provided a diverse scope of new boron-containing ibuprofen derivatives. [ABSTRACT FROM AUTHOR]

In this paper, a simple and efficient synthetic route for the preparation of new heterocyclic amino acid derivatives containing azetidine and oxetane rings was described. The starting (N-Boc-azetidin-3-ylidene)acetate was obtained from (N-Boc)azetidin-3-one by the DBU-catalysed Horner–Wadsworth–Emmons reaction, followed by aza-Michael addition with NH-heterocycles to yield the target functionalised 3-substituted 3-(acetoxymethyl)azetidines. Methyl 2-(oxetan-3-ylidene)acetate was obtained in a similar manner, which was further treated with various (N-Boc-cycloaminyl)amines to yield the target 3-substituted 3-(acetoxymethyl)oxetane compounds. The synthesis and diversification of novel heterocyclic amino acid derivatives were achieved through the Suzuki–Miyaura cross-coupling from the corresponding brominated pyrazole–azetidine hybrid with boronic acids. The structures of the novel heterocyclic compounds were confirmed via 1H-, 13C-, 15N-, and 19F-NMR spectroscopy, as well as HRMS investigations. [ABSTRACT FROM AUTHOR]

Drug delivery systems, which use components at the nanoscale level as diagnostic tools or to release therapeutic drugs to particular target areas in a regulated manner, are a fast-evolving field of science. The active pharmaceutical substance can be released via the drug delivery system to produce the desired therapeutic effect. The poor bioavailability and irregular plasma drug levels of conventional drug delivery systems (tablets, capsules, syrups, etc.) prevent them from achieving sustained delivery. The entire therapy process may be ineffective without a reliable delivery system. To achieve optimal safety and effectiveness, the drug must also be administered at a precision-controlled rate and the targeted spot. The issues with traditional drug delivery are overcome by the development of stimuli-responsive controlled drug release. Over the past decades, regulated drug delivery has evolved considerably, progressing from large- and nanoscale to smart-controlled drug delivery for several diseases. The current review provides an updated overview of recent developments in the field of stimuli-responsive boron-based materials in drug delivery for various diseases. Boron-containing compounds such as boron nitride, boronic acid, and boron dipyrromethene have been developed as a moving field of research in drug delivery. Due to their ability to achieve precise control over drug release through the response to particular stimuli (pH, light, glutathione, glucose or temperature), stimuli-responsive nanoscale drug delivery systems are attracting a lot of attention. The potential of developing their capabilities to a wide range of nanoscale systems, such as nanoparticles, nanosheets/nanospheres, nanotubes, nanocarriers, microneedles, nanocapsules, hydrogel, nanoassembly, etc., is also addressed and examined. This review also provides overall design principles to include stimuli-responsive boron nanomaterial-based drug delivery systems, which might inspire new concepts and applications. [ABSTRACT FROM AUTHOR]

We report an efficient method to prepare polysubstituted 3-hydroxypyridines from amino acids, propargyl alcohols, and arylboronic acids. The process involves Pd(0)-catalyzed anti-selective arylative cyclizations of N-propargyl-N-tosyl-aminoaldehydes with arylboronic acids ("anti-Wacker"-type cyclization), oxidation of the resulting 5-substituted-3-hydroxy-1,2,3,6-tetrahydropyridines to 3-oxo derivatives, and elimination of p-toluenesulfinic acid. This method provides diverse polysubstituted 3-hydroxypyridines, whose hydroxy group can be further substituted by a cross-coupling reaction via a triflate. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis and catalytic testing of a palladium complex with a 5-membered chelating [N,O] ligand, derived from the condensation of 2,6-diisopropylphenyl aniline and maple lactone. This catalyst was active towards the Suzuki-Miyaura cross-coupling reaction, and its activity was optimised through the selection of base, solvent, catalytic loading and temperature. The optimised conditions are mild, occurring at room temperature and over a short timescale (1 h) using solvents considered to be 'green'. A substrate scope was then carried out in which the catalyst showed good activity towards aryl bromides with electron-withdrawing groups. The catalyst was active across a broad scope of electron-donating and high-withdrawing aryl bromides with the highest activity shown for weak electron-withdrawing groups. The catalyst also showed good activity across a range of boronic acids and pinacol esters with even boronic acids featuring strong electron-withdrawing groups showing some activity. The catalyst was also a capable catalyst for the cross-coupling of aryl chlorides and phenylboronic acid. This more challenging reaction requires slightly elevated temperatures over a longer timescale but is still considered mild compared to similar examples in the literature. [ABSTRACT FROM AUTHOR]

A diboronic acid anthracene-based fluorescent system for detecting blood glucose could be used for 180 days. However, there has not yet been a boronic acid immobilized electrode to selectively detect glucose in a signal-increased way. Considering malfunctions of sensors at high sugar levels, the electrochemical signal should be increased proportionally to the glucose concentration. Therefore, we synthesized a new diboronic acid derivative and fabricated the derivative-immobilized electrodes for the selective detection of glucose. We performed cyclic voltammetry and electrochemical impedance spectroscopy with an Fe(CN)63−/4− redox pair for detecting glucose in the range of 0–500 mg/dL. The analysis revealed increased electron-transfer kinetics such as increased peak current and decreased semicircle radius of Nyquist plots as the glucose concentration increased. The cyclic voltammetry and impedance spectroscopy showed that the linear detection range of glucose was 40 to 500 mg/dL with limits of detection of 31.2 mg/dL and 21.5 mg/dL, respectively. We applied the fabricated electrode to detect glucose in artificial sweat and obtained 90% of the performance of the electrodes in PBS. Cyclic voltammetry measurements of other sugars such as galactose, fructose, and mannitol also showed linear increased peak currents proportional to the concentrations of the tested sugars. However, the slopes of the sugars were lower than that of glucose, indicating selectivity for glucose. These results proved the newly synthesized diboronic acid is a promising synthetic receptor for developing a long-term usable electrochemical sensor system. [ABSTRACT FROM AUTHOR]

Sialic acid (SA) is a well-known component of glycoproteins, which have applications in various functional processes on the cell's surface. The colorimetric is a simpler and more convenient method for measuring SA due to its low-cost apparatus and visual signal changes. This work focused on the unpredictable interparticle crosslinking aggregation of the functionalized gold nanoparticles (AuNPs) in complex media. We proposed a balance of the Derjaguin–Landau–Verwey–Overbeek (DLVO)-type aggregation and molecule-based interaction method to solve this problem. Here, we report a novel colorimetric assay for the determination of SA using 4-mercaptophenyl boronic acid (4-MPBA) as an analyte's recognition molecule, and negative charge PEG400 was used to repulsive the interparticle crosslinking. The proposed sensing platform shows a linear relationship between the ratio of the absorbance intensity (A525/A660) and concentration of SA from 0.05 to 8 mM (R2 = 0.997) and a detection limit of 48 μM was observed. The novel gold-based colorimetric sensor is easy to fabricate, reproducible in its test performance and has been successfully applied for the detection of SA in biological and healthcare product samples. [ABSTRACT FROM AUTHOR]