Boronic Acid Groups Research Articles

Photonic Plasticines with Uniform Structural Colors, High Processability, and Self-Healing Properties.

Despite the vast variety of colloidal superstructures available in soft matter photonics, it remains challenging to balance the trade-off between their optical microstructures and material processability. By synergizing colloidal photonics and dynamic chemistry, a type of photonic "plasticine" with characteristics of uniform structural colors, high processability, and self-healing is demonstrated. Specifically, a boronate ester bond-based macromonomer is first prepared through complexation between the diols of polyvinyl alcohol and the boronic acid group of 3-(acrylamido) phenylboronic acid in the presence of concentrated silica colloids. Upon photopolymerization, the dynamic photonic plasticine is formed in situ as the result of the crosslinking of the boronate ester bonded networks. The randomly packed colloids inside the plasticine compose the amorphous photonic crystals, giving rise to angle-independent structural colors that would not compromise during subsequent processing steps; the reversible nature of the boronate ester bonds endows the plasticine with self-adaptable and self-healing properties. Further, the plasticine is also compatible with common shaping methods, that is, cutting, molding, and carving, and thus can be facilely processed into 3D structural colored objects, holding great potentials in fields such as bio-encoding, optical filters, anti-counterfeiting, etc.

A nanosized metal–organic framework for visual detection of fluoride ions with smartphone via colorimetric test kit

Fluoride ion (F−) is an essential micronutrient in the human body, however, an abnormal large intake of F− can result in adverse effects, such as skeletal fluorosis or DNA damage. Therefore, it is of great significance to develop convenient assays for the visual detection of F− with high sensitivity. We rationally developed the nanosized iron-based metal organic frameworks (Fe-MOFs) by using 3,5-dicarboxybenzeneboronic acid as organic linkers and Fe3+ as metal ions through the solvothermal method, which can be applied for detecting F− with high sensitivity and selectivity owing to the specific recognition of boronic acid groups towards F− and the strong binding affinity between F− and Fe3+. The Fe-MOFs possess excellent peroxidase-like activity, which can be effectively inhibited by F−. Moreover, a portable test kit for the determination of F− was developed by embedding Fe-MOFs into hydrogel, and the visual measurement of F− was realized based on smartphone by identifying the color signal of the oxidation of 3,3',5,5'-tetramethylbenzidine dihydrochloride. The output signal (R/G) was linear with F− concentration in the range of 10.0–200.0 μM. The Fe-MOFs-based colorimetric strategy is easy-operation, low-cost and equipment-free, which has been further applied to detect F− in the real water samples.

Photoelectron spectroscopy of arylboronic acids

We report the gas-phase UV photoelectron spectra (UPS) of some arylboronic acids for the first time. The electronic structures of 2-methyl-, 3-methyl- and 3-chloro-phenylboronic acids and 3-thienyl-boronic acid have been studied in the gas phase by HeI/HeII photoelectron spectroscopy and EOM-CCSD quantum chemical calculations. The comparison of the spectra of arylboronic acids with the spectra of toluene, chlorobenzene and thiophene shows remarkably small changes in the ionization energies of the highest occupied π-orbitals upon the attachment of the boronic acid group B(OH)2 to the aryl core. The appearance of additional spectral bands with ionization energies of 10.5–11 eV corresponds to ionization of CB σ-bonding orbitals.

Functionalized polyoxometalate microspheres ensure selective adsorption of phosphoproteins and glycoproteins.

Lacunary polyoxometalate (POM), [PW9O34]9-, grafts with a boronic acid group attached via an organosilane bridge assemble into microspheres, PW9-Si-APBA. The oxygen-rich and hydrophilic surface of POM facilitates the binding of phosphate groups in phosphoproteins and glycans in glycoproteins. While the metal-oxo in POM provides π-π interactions with the phosphate groups of phosphoproteins, the boronic acid group specifically binds to glycoproteins via the cis-diols of glycans. Therefore, these multi-driving forces ensure the selective adsorption of phosphoproteins and glycoproteins by PW9-Si-APBA microspheres in biological sample matrixes, even in the presence of very high protein abundance, i.e., BSA, at mass ratio of β-ca/IgG/OVA/BSA = 1 : 1 : 1 : 200.

Preparation of a magnetic and recyclable superparamagnetic silica support with a boronic acid group for immobilizing Pd catalysts and its applications in Suzuki reactions.

Palladium is one of the best metal catalysts for Suzuki cross-coupling reaction to synthesize unsymmetrical biaryl compounds. However, homogeneous palladium (Pd) is limited in an industrial scale due to the high cost, separation, removal, and recovery issues. In this paper, a novel, high activity magnetic nanoparticles (Fe3O4@SiO2-APBA-Pd) catalyst was prepared by a simple, cost-effective procedure. The as-prepared functional nanoparticles (Fe3O4@SiO2-APBA) with boric acid group immobilized Pd through adding Pd(OAc)2 to Fe3O4@SiO2-APBA in absolute ethanol and maintaining for a certain time under a nitrogen atmosphere. The as-prepared catalyst was characterized by FT-IR, SEM, EDX, TEM, ICP-MS, XPS, and XRD. The results showed that the Pd (0.2–0.6 nm) was successfully anchored on the magnetic silica material with boric acid group. The amount of Pd was 0.800 mmol g−1. This magnetic nanostructure (8–15 nm) is especially beneficial as a nanocatalyst because each nanoparticle can catalyze a reaction in a certain time without steric restriction, which could effectively improve the reaction efficiency. The current nanoparticles with the Pd catalyst could be used as a novel, green, and efficient heterogeneous catalyst for Suzuki reactions. This catalyst showed promising catalytic activity and excellent yields toward 14 kinds of Suzuki coupling reactions under mild reaction conditions, which was similar to homogeneous Pd and many reported heterogeneous Pd catalysts. In addition, the turnover number (TON) and turnover frequency (TOF) for the Suzuki reaction were high. TOF and TON were 9048 h−1 and 20 250 for the Suzuki reaction of bromobenzene and phenylboronic acid. Furthermore, the nanoparticles could be easily separated by a magnet, and could be used repeatedly seven times without any significant loss in activity.

Using boronic acid functionalization to simultaneously enhance electrical conductivity and thermoelectric performance of free-standing polythiophene film

Poly(3-thiophene boronic acid) (PTBA) as a boronic acid functionalized conducting polymer has been developed in sensors and electrochromics due to the characteristic feature of boronic acid groups, however, the previously reported PTBA had a very low electrical conductivity of 2.0 × 10−9 S cm−1, and up to day there are no researches on PTBA used as thermoelectric materials. In this study, a free-standing PTBA film with high-quality was firstly electrosynthesized in acetonitrile containing boron trifluoride diethyl etherate (1:1 by volume). SEM, FT-IR, UV–vis and TG were conducted to investigate morphologies, structures and thermal stability of PTBA films. Notably, the introduction of boronic acid groups in polythiophene significantly increases the Seebeck coefficient from 72.5 to 125.0 μV K−1, electrical conductivity from 0.014 to 0.027 S cm−1, and power factor from 0.0074 to 0.0422 μW m−1 K−2. Free-standing PTBA film will be a promising material in the field of thermoelectric.

Boronic Acid-Mediated Activity Control of Split 10-23 DNAzymes.

The 10–23 DNAzyme is an artificially developed Mg2+‐dependent catalytic oligonucleotide that can cleave an RNA substrate in a sequence‐specific fashion. In this study, new split 10–23 DNAzymes made of two nonfunctional fragments, one of which carries a boronic acid group at its 5′ end, while the other has a ribonucleotide at its 3′ end, were designed. Herein it is demonstrated that the addition of Mg2+ ions leads to assembly of the fragments, which in turn induces the formation of a new boronate internucleoside linkage that restores the DNAzyme activity. A systematic evaluation identified the best‐performing system. The results highlight key features for efficient control of DNAzyme activity through the formation of boronate linkages.

A novel electrochemical non-enzymatic glucose sensor based on Au nanoparticle-modified indium tin oxide electrode and boronate affinity

In this article, a sandwich-type electrochemical sensor for selective determination of glucose based on the formation of glucose-boronic bidentate complex has been developed. 3-aminophenylboronic acid (m-APBA) was immobilized on the gold nanoparticles modified ITO electrode with the linker molecule 4-mercaptobenzoic acid (p-MBA). Then, glucose was captured by boronic acid group from m-APBA as the primary receptor and further grafted with an electroactive ferroceneboronic acid (FcBA) as the secondary receptor to form the sandwich-type sensor for selective detection of glucose. For comprehensively understanding the effect of the charge and structure of the terminal boronic acid group of 3-APBA on its binding to glucose, surface pKa was studied by electrochemical titration method, and it was proved the feasibility of examining glucose in physiological condition by the sandwich-type electrochemical sensor. The electrochemical characteristics of the as-prepared sensor were investigated by using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The electrochemical sensor displayed a linear detection range of glucose from 0.5 mmol L−1 to 30 mmol L−1, with detection limit of 43 µmol L−1. The sensor exhibited good performance in selectivity study with the coexistence of galactose, fructose, mannose and other common interferences in physiological environment, such as, uric acid, ascorbic acid and dopamine. The as-prepared electrode with high sensitivity, good stability and reproducibility as well as excellent biocompatibility made it promising for the development of enzyme-free sensors.

Facile synthesis of 5-arylidene rhodanine derivatives using Na2SO3 as an eco-friendly catalyst. Access to 2-mercapto-3-aryl-acrylic acids and a benzoxaborole derivative

A simple, efficient and environment-friendly procedure for the synthesis of 5-arylidene rhodanines derivatives via a Knoevenagel type reaction was developed using rhodanine, a variety of differently substituted aldehydes and Na2SO3 as benign catalyst in ethanol. Selected 5-arylidene rhodanines were subjected to basic hydrolysis to afford 2-mercapto-3-substituted-acrylic acids. The presence of a boronic acid group is well tolerated in such transformations. In the case of 2-formylphenylboronic acid, this sequence opens access to a new benzoxaborole derivative.

Dynamic control of boron esters

Photochemistry Visible light at different frequencies can photoswitch azobenzenes between their E and Z isomers. Accardo et al. used the isomerization of ortho-substituted azobenzene boronic acids to tune the affinity for diols to bind and form esters. Methoxy groups ortho to the azo group on the ring opposite the boronic acid group destabilized diol binding to the E isomer. The E isomer also formed favorable hydrogen bonds to water that inhibited displacement by the diol. Both effects helped to boost the relative binding affinity for ethylene glycol binding to the Z versus E isomer to more than 20. They exploited this effect to create photoswitchable gels formed between four-arm amine-terminated poly(ethylene glycol)s that had end groups of either azobenzene boronic acids or extended diols. J. Am. Chem. Soc. 10.1021/jacs 0c08551 (2020).

Biomimetic Boroxine-Based Multifunctional Thermosets via One-Pot Synthesis.

Boroxine-based thermosets with remarkable mechanical tunability, self-healing ability, recyclability, and adhesive strength are of significant importance in various applications. However, complex multistep reactions are often required to prepare such thermosets. Herein, a facile one-pot approach to synthesize boroxine-based malleable thermosets is proposed. Random copolymers with pendant boronic acid groups were synthesized from alkenyl monomers containing boronic acids [4-vinylphenylboronic acid (4-VPBA), 3-vinylphenylboronic acid, or 3-acrylamidophenylboronic acid] and octadecanoxy polyethylene glycol methacrylate. Then, the as-prepared copolymers were cured to form thermosets with boroxine bonds. The tensile strengths of the thermosets were tailored to range from 9.3 to 27.5 MPa by increasing the concentration of 4-VPBA. Moreover, because of the reversible nature of dynamic boroxine bonds (transformation between boroxines and boronic acids) induced by water, the thermosets exhibit remarkable self-healing efficiency (up to 99%), tunable mechanical properties, and excellent recyclability. Additionally, the thermosets also demonstrate superior adhesive strength (as high as 73.9 MPa) on different substrates.

Graphene Oxide-based Magnetic Boronate-affinity Adsorbent for Extraction of Horseradish Peroxidase

Graphene oxide (GO) is a two-dimensional atom-thick sheet generated from an oxidation of graphene. GO possesses a range of reactive oxygen functional groups on the basal planes and edges, which makes it a good candidate in the field of separation and enrichment through chemical functionalization. In this work, GO-based Fe3O4 magnetic nanoparticles were prepared, and boronic acid groups were introduced by 3-aminophenylboronic acid (APBA) at the same time to improve the enrichment efficiency. Herein, the GO-based magnetic boronate-affinity adsorbent (Fe3O4@[email protected]) was developed focusing on the specific capture of low abundance of glycoprotein. The composites gathered excellent characters of large specific surface area and biocompatibility of GO, strong magnetic responsiveness, and enhanced affinity properties of boronic acid. The proposed system showed better specificity for glycoprotein even in the presence of non-glycoproteins. As a result, the prepared Fe3O4@[email protected] not only exhibited high selectivity for horseradish peroxidase (HRP), and an outstanding tolerance for interference, but also showed excellent rebinding rate for an extraction application. Furthermore, this method provided a reliable way to improve conventional magnetic adsorbent, and showed great potential in analysis of low-abundant glycoprotein from even complex samples.

Oriented Immobilization of Protein Templates: A New Trend in Surface Imprinting.

In this Review, we have summarized recent trends in protein template imprinting. We emphasized a new trend in surface imprinting, namely, oriented protein immobilization. Site-directed proteins were assembled through specially selected functionalities. These efforts resulted in a preferably oriented homogeneous protein construct with decreased protein conformation changes during imprinting. Moreover, the maximum functionality for protein recognition was utilized. Various strategies were exploited for oriented protein immobilization, including covalent immobilization through a boronic acid group, metal coordinating center, and aptamer-based immobilization. Moreover, we have discussed the involvement of semicovalent as well as covalent imprinting. Interestingly, these approaches provided additional recognition sites in the molecular cavities imprinted. Therefore, these molecular cavities were highly selective, and the binding kinetics was improved.

Theoretical Studies on The Structural, Vibrational, Conformational Analysis and Nonlinear Optic (NLO) Property of 4-(Methoxycarbonyl) Phenylboronic Acid

In this paper, the structural, electronic, non-linear optical (NLO) properties and vibrational frequencies of 4-(methoxycarbonyl) phenylboronic acid has been examined theoretically using ab initio Hartree-Fock (HF) and Density Functional Theory (DFT/B3LYP) methods applying the standard 6-311++G(d,p) basis set. 1H- and 13C-chemical shifts were calculated by employing the direct implementation of the gauge including-atomic-orbital (GIAO) method at the B3LYP/6-311++G(d,p) and HF/6-31G(d) levels of the theory. There are two conformers, (cis-trans = ct) and (trans-cis = tc) for title molecule. The energy difference between ct and tc conformers of studied molecule are of 0.126 kcal/mol with B3LYP/6-311++G(d,p) and 0.138 kcal/mol with HF/6-311++G(d,p), respectively. The conformer ct is more stable than the conformer tc. Also, the energy gap (ΔΕg) differences between the highest occupied (HOMO) and lowest unoccupied molecular orbitals(LUMO), dipole moment, polarizability and first static hyperpolarizability were calculated as a function of both dihedral angle (C3-C4-C7-O3), between methoxycarbonyl group (CH3-O-CO-) and benzene ring, and dihedral angle (C2-C1-B-O1), between boronic acid group (-B(OH)2) and benzene ring. In the change of the energy gap and polarizability depending on dihedral angles, it was shown that the polarizabilities were follow inverse relationship the energy gaps.

"All-inclusive" silicon nanoparticles for sensitive detection of blood glucose

In this study, a success is achieved in developing a new variety of "all-inclusive" silicon nanoparticles with recognition components of boronic acid groups and anti-fouling components of PEG segments for the precise detection of glucose. The added glucose will contribute to the significant fluorescence quenching of "all-inclusive" silicon nanoprobes. Not only does this method achieve the accurate detection of glucose in the range of 0.4 to 10 μM with a detection limit of 0.27 μM, it is also applicable to the clinical analysis of blood glucose.

Boronic Acids and Their Derivatives in Medicinal Chemistry: Synthesis and Biological Applications.

Boron containing compounds have not been widely studied in Medicinal Chemistry, mainly due to the idea that this group could confer some toxicity. Nowadays, this concept has been demystified and, especially after the discovery of the drug bortezomib, the interest for these compounds, mainly boronic acids, has been growing. In this review, several activities of boronic acids, such as anticancer, antibacterial, antiviral activity, and even their application as sensors and delivery systems are addressed. The synthetic processes used to obtain these active compounds are also referred. Noteworthy, the molecular modification by the introduction of boronic acid group to bioactive molecules has shown to modify selectivity, physicochemical, and pharmacokinetic characteristics, with the improvement of the already existing activities. Besides, the preparation of compounds with this chemical group is relatively simple and well known. Taking into consideration these findings, this review reinforces the relevance of extending the studies with boronic acids in Medicinal Chemistry, in order to obtain new promising drugs shortly.

Construction and characterization of sandwich-type laccase electrode based on functionalized conducting polymers

Laccase (Lac) is a multi-active-center glycoprotein. Its heterogeneous electron transfer efficiency depends on the distance between the substrate binding site and the electrode surface. Laccase encapsulation by conducting polymers should be favorable for the direct electron transfer (DET) process, thus improving the electrocatalytic efficiency of the laccase electrode. Here, a sandwich-type laccase electrode based on functionalized conducting polymers was developed. First, porous poly (3-aminophenylboronic acid) (PAPBA) conductive film was electrodeposited on a glassy carbon electrode (GCE), and on which laccase was then immobilized via the specific binding of the boronic acid group from PAPBA and the glycosyl group on laccase. In addition to higher laccase loading, the present Lac/PAPBA/GCE electrode is more robust than that prepared by physical adsorption of laccase on conducting polymer. For laccase to be wired better, a poly (3,4-ethylenedioxythiophene) (PEDOT) conductive film with polystyrenesulfonate anion (PSS−) as dopant was electrochemically covered on the Lac/PAPBA/GCE. In addition to the compatibility among the stability of the cyclic boronic acid ester, the biological activity of the laccase, and the polymer conductivity, the sandwich-type laccase electrode was demonstrated to be more efficient than the counterpart without the second layer for the electroreduction of O2 probably due to a so-called “cage effect”. The "cage effect" of the sandwich-type conducting polymers reduces the requirement for laccase orientation and greatly improves the electrocatalytic performance of the laccase electrode.

Catechol Containing Polyelectrolyte Complex Nanoparticles as Local Drug Delivery System for Bortezomib at Bone Substitute Materials.

The proteasome inhibitor bortezomib (BZM) is one of the most potent anti-cancer drugs in the therapy of multiple myeloma. In this study, an adhesive drug delivery system (DDS) for BZM was developed. Therefore, we extended the present DDS concept of polyelectrolyte complex (PEC) nanoparticle (NP) based on electrostatic interactions between charged drug and polyelectrolyte (PEL) to a DDS concept involving covalent bonding between PEL and uncharged drugs. For this purpose, 3,4-dihydroxyphenyl acetic acid (DOPAC) was polymerized via an oxidatively induced coupling reaction. This novel chemo-reactive polyanion PDOPAC is able to temporarily bind boronic acid groups of BZM via its catechol groups, through esterification. PDOPAC was admixed to poly(l-glutamic acid) (PLG) and poly(l-lysine) (PLL) forming a redispersible PEC NP system after centrifugation, which is advantageous for further colloid and BZM loading processing. It was found that the loading capacity (LC) strongly depends on the PDOPAC and catechol content in the PEC NP. Furthermore, the type of loading and the net charge of the PEC NP affect LC and the residual content (RC) after release. Release experiments of PDOPAC/PEC coatings were performed at medically relevant bone substitute materials (calcium phosphate cement and titanium niobium alloy) whereby the DDS worked independently of the surface properties. Additionally, in contrast to electrostatically based drug loading the release behavior of covalently bound, uncharged BZM is independent of the ionic strength (salt content) in the release medium.

Direct Electrochemistry and Sensitive Detection of Guanosine on Nanopolymeric Surfaces Bearing Boronic Acid Groups

AbstractThis paper describes the use of novel boronic acid containing polymeric surfaces for following improved direct electrochemistry and highly sensitive and selective electrochemical detection of guanosine. Effective and robost boronic acid containing electroactive polymeric layers based on poly(3‐aminophenylboronic acid) (PAPBA) in the existence of a convenient nanomaterial (multi‐walled carbon nanotubes, MWCNTs) were fabricated onto graphite surfaces with a simple and reproducible single‐step electro‐fabrication method for the first time. So‐formed electrodes were then utilized for direct electrochemistry of guanosine and determination of guanosine. The electrode presented a linearity to guanosine from 1 μM to 120 μM and the detection limit was calculated as 0.14 μM (n=3). It was feasible to differentiate guanine and guanosine with a good peak separation value of 0.31 V. Furthermore, analytical performance of this novel electrode was compared with the performances of graphene added polymeric layer modified graphite electrode and unmodified graphite electrode.

Facile synthesis of N,B-co-doped carbon dots with the gram-scale yield for detection of iron (III) and E. coli

A simple method was developed to prepare fluorescent nitrogen/boron-doped carbon dots (N,B-CDs) in the gram scale. The results showed that the CDs exhibited blue photoluminescence (PL) under 365 nm ultraviolet radiation and excitation-dependent emission. Heteroatoms entered the CDs to enhance the photochemical properties, and their positive properties can be attributed to the presence of guanidino group and functionalized with boronic acid for realizing their utilization in certain applications. These materials could be applied to monitor Fe3+ via static PL quenching, yielding a limit of detection (LOD) of 0.74 μM. Furthermore, the charged and boronic acid groups on the prepared N,B-CDs enabled their use as recognition elements to bind with the bacteria through electrostatic interaction and allowed covalent interactions to form the corresponding boronate ester with E. coli (E. coli) bacterial membrane. This method could satisfy a linear range of 102–107 with LOD of 165 cfu ml−1 for E. coli. This method was applied for the determination of E. coli in tap water and orange juice samples, and satisfactory results were obtained.