Anilineboronic Acid Research Articles

Redox Properties of Poly (aniline boronic acid) in Aqueous Environment with Glucose and Table Sugar Addition

Redox Properties of Poly (aniline boronic acid) in Aqueous Environment with Glucose and Table Sugar Addition

Eco-friendly poly(aniline boronic acid)/gum tragacanth stabilized silver nanoparticles nanocomposite for selective sensing of Hg2+

The stable and dispersed aqueous nanocomposite of poly(aniline boronic acid)/gum tragacanth stabilized silver nanoparticles (PABA/GT@AgNPs) was synthesized and applied as a colorimetric nanoprobe for Hg2+. Aniline boronic acid was used as the only reducing agent of silver nitrate and equally oxidized to PABA based on in situ chemical oxidative polymerization. In the presence of gum tragacanth (GT), hydroxyl groups of GT will bind to PABA at boronic groups to generate the PABA/GT matrix, on which AgNPs are anchored. At the optimal synthesis, absorption spectra at 285 and 421 nm correspond to π -π* transitions of PABA and plasmon resonance band of small sized AgNPs (10–15 nm). Based on the FTIR spectrum, GT is the major constituent of nanocomposite. Under optimal conditions (40 mM phosphate buffer pH 6.0, 150 mM sodium chloride, reaction time of 8 min at room temperature), the PABA/GT@AgNPs was used as a sensing of Hg2+ based on Hg2+ induced transmetalation on arylboronic acid group and redox reaction with Ag0. In the presence of Hg2+, the aggregation of PABA/GT@AgNPs can be seen by a color change from pale yellow to colorless and a blue shift from 407 nm to 370 nm. Good linear ranges in the concentrations of 0.005–1.0 μM and 1.0–40.0 μM were achieved, with a detection limit of 0.85 nM. The practicality of the detection was demonstrated on tap and lake water samples, with no effects of other interfering ions, and satisfactory recoveries of 97–101 % and precisions of 2.9–5.6 %.

Synthesis of gold nanoparticles/polyaniline boronic acid/sodium alginate aqueous nanocomposite based on chemical oxidative polymerization for biological applications

Gold nanoparticles/polyaniline boronic acid/sodium alginate aqueous nanocomposite ((PABA-SAL)@AuNPs) was fabricated. Aniline boronic acid (ABA) served as reductant of gold salt, all within the SAL solution. While ABA reduced gold salt to its nanoparticles, the ABA monomer was also oxidized to its conducting polymeric form (PABA). The presence of PABA in the reaction mixture exerted solubility and stability challenge, thus SAL was used as stabilizer and solubilizer for PABA. The numerous cis-diol groups of SAL could bind to boronic acid groups of PABA to furnish PABA-SAL repeating polymer structure for AuNPs anchoring. Sparkling ruby red (PABA-SAL)@AuNPs have absorption peaks at 529 and 718 nm. Average particle sizes of nanocomposite were within 15–20 nm, with hydrodynamic diameter of 48.6 ± 0.9 nm, zeta potential of −32.5 ± 1.6 mV and conductivity value of 2015.3 ± 3.2 μS/cm. (PABA-SAL)@AuNPs possessed antibacterial activities against seafood associated bacterial isolates, with MIC and MBC ranging from 4 to 8 μg/mL. The moderate antioxidant capacity of (PABA-SAL)@AuNPs was observed, without any deleterious damages on human red blood cells. It also has good biocompatibility on Caco-2 and RAW 264.7, with cell viability not less than 70%. These results confirm the high prospect of (PABA-SAL)@AuNPs for possible biomedical applications.

In situ chemical polymerization of conducting polymer nanocomposites: Effect of DNA-functionalized carbon nanotubes and nitrogen-doped graphene as catalytic molecular templates

This work is part of our ongoing studies to develop conducting polymer nanocomposite-based sensors for detection of neurotransmitter dopamine, and reports on synthesis of a highly conductive, self-doped nanocomposite of polyaniline. Nanocomposites of poly (anilineboronic acid) (PABA) were fabricated through in situ chemical polymerization of 3-aminophenylboronic acid monomers in the presence and in the absence of different carbonaceous materials such as DNA-functionalized carbon nanotubes (DNA_CNT), nitrogen-doped graphene (NEG) and a hybrid structure of DNA-functionalized carbon nanostructures (DNA_CNT_NEG). Among the templates used, DNA_CNT_NEG acted as the best anchoring molecular template during polymerization, which increased the stability of the respective polymer nanocomposites after polymerization. This stability improvement was attributed to the formation of conductive state of polyaniline (emeraldine salt). The good pre-dispersion state of DNA_CNT_NEG in monomer solution increased the effective molecular interactions at the interfacial layer of nanofillers and monomers. This resulted in fabrication of highly-ordered and polyconjugated structure of PABA nanocomposites with superior electrical conductivity (14300 S m−1 at 3.0 wt% filler content) compared to pure PABA (4 × 10−9 S m−1) or polymer composites synthesized with neat CNT (1.75 × 10−4 S m−1 at 3.0 wt% filler content). PABA composites were also synthesized via in situ electrochemical polymerization of anilineboronic acid monomers in the presence of DNA_CNT_NEG using cyclic voltammetry technique, and were used to detect nanomolar concentrations of dopamine. The fabricated biosensor showed a very high sensitivity of 6 nM and a very wide linear range of 0.007–1 µM. The fabricated nanocomposite electrodes containing DNA_CNT_NEG are promising sensors for diagnosis of neurological disorders such as Parkinson’s.

A glassy carbon electrode modified with molecularly imprinted poly(aniline boronic acid) coated onto carbon nanotubes for potentiometric sensing of sialic acid.

A potentiometric sensor for sialic acid (SA) was developed based on molecular imprinting technique. The sensor was fabricated by modifying carbon nanotubes (CNT) and anSA-imprinted poly(aniline boronic acid) (PABA) film on a glassy carbon electrode (GCE). The detection strategy capitalizes on the change of electrochemical potential resulting from boronic acid-SA interaction. The imprinted PABA combines the functions of SA-binding boronic acid groups and the imprinting effect, thus endowing it with both chemical and sterical recognition capability. The imprint factor (IF, compared to a non-molecularly imprinted polymer) is 1.74. The sensor can well differentiate SA from its analogs at physiological pH values and has a linear potentiometric response (R2= 0.998) in 80μM to 8.2mM SA concentrations range with a detection limit of 60μM (at S/N= 3). The sensor was applied to the determination of SA in serum samples and gave recoveries between 93% and 105%. Graphical abstract Schematic presentation of the fabrication of a sialic acid (SA) imprinted poly(aniline boronic acid) (PABA)/CNT modified electrode. The electrode can well differentiate SA from its analogs at physiological pH and determine SA in human serum samples with satisfactory recoveries of 93%-105%.

Enhanced Sensitivity of Dopamine Biosensors: An Electrochemical Approach Based on Nanocomposite Electrodes Comprising Polyaniline, Nitrogen-Doped Graphene, and DNA-Functionalized Carbon Nanotubes

A new, highly-exfoliated nitrogen-doped graphene is electrochemically synthesized, which enhances the catalytic activity of poly(anilineboronic acid) nanocomposite electrodes for dopamine detection in the presence of excess ascorbic acid. The sensing approach is made up of poly(anilineboronic acid) nanocomposites electrodeposited on the surface of a glassy carbon electrode via in-situ electrochemical polymerization of anilineboronic acid monomers using cyclic voltammetry. A thin layer of DNA-functionalized carbon nanotubes, and nitrogen-doped graphene is coated on the electrode surface prior to electro-polymerization. During the electro-polymerization the π-π stacking and electrostatic interactions between DNA-coated carbon nanostructures and monomers anchors anilineboronic acid monomers on the electrode surface. This molecular anchoring increases electrodeposition of the respective nanocomposites on electrode; thus, greatly enhances the density of boronic acid receptors for dopamine binding. The coordinate covalent bonds between nitrogen atoms of graphene and boron atoms of anilineboronic acid monomers further increase the density of boronic acid groups for target analyte detection. The developed highly-sensitive and highly-selective biosensor is capable of dopamine detection in a wide linear range from 0.02-1μM, along with a detection limit of 14nM, which is a very significant step forward for dopamine detection and paves the way for molecular diagnosis of neurological illnesses such as Parkinson's disease.

Boron-nitrogen-phosphorous doped graphene nanoplatelets for enhanced electrocatalytic activity

Doping with foreign atoms is a powerful technique for modifying the inherent properties of a host materials. In this work, we report a strategy for preparing multiple heteroatom-doped graphene nanoplatelets (GnPs). Poly(anilineboronic acid, PABA), which is one of the conducting polymers, was in-situ grafted to edge-amine functionalized GnPs (A-GnPs) in phosphoric acid. The isolated PABA grafted A-GnPs phosphoric acid salts (PA-GnP salts) were heat-treated at 900 °C under argon atmosphere to yield boron (B)-nitrogen (N)-phosphorus (P) doped GnPs (BNP-GnPs). The structure of the BNP-GnPs was confirmed by various techniques, including transmission electron microscopy, scanning electronic microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and thermogravimetric analysis. The BNP-GnPs demonstrated significantly improved electrocatalytic activity towards the oxygen reduction reaction, suggesting that BNP-GnPs can be one of the best alternatives to precious Pt-based electrocatalysts.

Electrochemical sensor for dopamine based on imprinted silica matrix-poly(aniline boronic acid) hybrid as recognition element

A novel imprinted silica matrix-poly(aniline boronic acid) hybrid for electrochemical detection of dopamine (DA) was developed. Boronic acid functionalized conducting polymer was electrochemically prepared on Au electrode. The number of covalent binding sites toward DA templates was controlled by potential cycles. A precursory sol solution of ammonium fluorosilicate (as cross-linking monomer) containing DA was spin-coated on the polymer modified electrode. Under NH3 atmosphere, the hydroxyl ions were generated in the solution and catalyzed the hydrolysis of fluorosilicate to form silica matrix. After this aqueous sol-gel process, an inorganic framework around the DA template was formed and the imprinted hybrid for DA was also produced. As revealed by scanning electron microscopy, UV-vis spectroscopy and cyclic voltammetry characterization, DA was embedded in the imprinted hybrid successfully. The affinity and selectivity of the imprinted hybrid were also characterized by cyclic voltammetry. The imprinted hybrid showed higher affinity for DA than that for epinephrine, and little or no affinity for ascorbic acid and uric acid due to the combined effects of covalent interaction, cavities matching and electrostatic repulsion. The imprinted hybrid sensor exhibited a quick response (within 5min) to DA in the concentration range from 0.05 to 500μmolL−1 with a detection limit of 0.018μmolL−1. The prepared sensor was also applied to detect DA in real samples with a satisfactory result.

Molecular imprinted polymer functionalized carbon nanotube sensors for detection of saccharides

In this work, we report the synthesis and fabrication of an enzyme-free sugar sensor based on molecularly imprinted polymer (MIP) on the surface of single walled carbon nanotubes (SWNTs). Electropolymerization of 3-aminophenylboronic acid (3-APBA) in the presence of 10 M d-fructose and fluoride at neutral pH conditions resulted in the formation of a self-doped, molecularly imprinted conducting polymer (MICP) via the formation of a stable anionic boronic ester complex between poly(aniline boronic acid) and d-fructose. Template removal generated binding sites on the polymer matrix that were complementary to d-fructose both in structure, i.e., shape, size, and positioning of functional groups, thus enabling sensing of d-fructose with enhanced affinity and specificity over non-MIP based sensors. Using carbon nanotubes along with MICPs helped to develop an efficient electrochemical sensor by enhancing analyte recognition and signal generation. These sensors could be regenerated and used multiple times unlike conventional affinity based biosensors which suffer from physical and chemical stability.

A novel potentiometric sensor based on a poly(anilineboronic acid)/graphene modified electrode for probing sialic acid through boronic acid-diol recognition

A novel potentiometric approach was described for probing sialic acid (SA) using a poly(anilineboronic acid)/graphene modified glassy carbon (GC) electrode. The proposed electrode was prepared by electrodeposition of reduced graphene oxide (ERGO) at a GC electrode and then coated with a poly(anilineboronic acid) (PABA) film by electropolymerization of its monomer. Principle of SA detection at the PABA/ERGO/GC electrode was ascribed to a reversible and covalent boronic acid-diol binding which was sensitive to the electrochemical potential of the prepared sensor. The graphene layer introduced on the electrode surface was shown to dramatically improve the sensitivity of the sensor response. Under optimum conditions, the proposed sensor exhibited low detection limit of 0.8μM with a wide linear range of 2μM–1.38mM, high stability, good regeneration, and remarkable selectivity. For the analysis of SA in human blood serum, the high accuracy and good recoveries revealed the great potential in the practical applications.

Potentiometric Detection of Saccharides Based on Highly Ordered Poly(aniline boronic acid) Nanotubes

Potentiometric detection of saccharides based on highly ordered poly(aniline boronic acid) (PABA) nanotubes modified electrode was systematically investigated. The PABA nanotubes were first fabricated by electrochemical polymerization of 3-Aminophenylboronic acid in an anodic alumina oxide (AAO) membrane. Their morphologies and structure were then characterized using scanning electron microscopy and FT-IR spectroscopy. The as-synthesized PABA nanotubes had a very porous structure with small diameters and high surface area. The sensitivity and response time of PABA nanotubes modified electrode to saccharides were discussed. The sensitivity of the sensor in connection with length of PABA nanotubes and pH of the solution was studied. The sensor showed much high sensitivity to D-glucose (ca. 1.5mVmM−1) and D-fructose (ca. 3.5mVmM−1) with fast response time for D-glucose (65s) and D-fructose (23s).

Poly(3-aminophenylboronic acid)-functionalized carbon nanotubes-based chemiresistive sensors for detection of sugars.

The poly(aniline boronic acid) (PABA)-functionalized single-walled carbon nanotube (SWNT) non-enzymatic sensor was developed for the detection of saccharides. The work involved the electrochemical polymerization of 3-aminophenylboronic acid (3-APBA) in the presence of fluoride on the surface of SWNTs and their subsequent evaluation as chemiresistive sensors towards the detection of d-fructose and d-glucose. By varying the sensor's synthesis conditions by charge-controlled electropolymerization, the sensing performance was systematically optimized. Through electrical characterization in terms of change in resistance, cyclic voltammetry confirmed the electrochemical deposition of the PABA coating on the SWNTs. The optimized sensors showed sensing response over a wide dynamic range of concentrations and a limit of detection of 2.92 mM for D-fructose and 3.46 mM for D-glucose. The hybrid sensors could be regenerated on the basis of the reversible nature of the binding between PABA and 1,2- or 1,3-diols at lower values of pH.

Rapid electrodeposition of a gold-Prussian blue nanocomposite with ultrahigh electroactivity for dual-potential amperometric biosensing of uric acid.

We report a new and efficient protocol for rapid electrodeposition of a gold-Prussian blue ((Au-PB)REd) nanocomposite with ultrahigh electroactivity on an Au electrode by cyclic voltammetry in 0.1 M aqueous K2SO4 containing 1 mM K3Fe(CN)6, 1 mM HAuCl4, and 0.1 mM Fe2(SO4)3, and an electrochemical quartz crystal microbalance and scanning electron microscopy were utilized to investigate the electrodeposition. The (Au-PB)REd/Au electrode was then cast-coated with a urate oxidase (UOx)-poly(anilineboronic acid) (PABA)-Pt nanoparticle (PtNP) bionanocomposite and chitosan (CS) for high-performance amperometric biosensing of uric acid (UA) in the dual-potential mode. The UOx-PABA-PtNP bionanocomposite was prepared through chemical oxidation of anilineboronic acid (ABA) by sodium chloroplatinate in the presence of UOx. The thus-fabricated CS/UOx-PABA-PtNP/(Au-PB)REd/Au enzyme electrode worked well under optimized conditions through both oxidation and reduction determination of enzyme-generated H2O2, which responded linearly to UA concentrations from 0.3 μM to 0.65 mM with a sensitivity of 223 μA mM(-1) cm(-2) and a limit of detection (LOD) of 0.2 μM (0.7 V vs. SCE), and from 0.2 μM to 0.25 mM with a sensitivity of 247 μA mM(-1) cm(-2) and a LOD of 0.1 μM (-0.05 V vs. SCE), being superior to most analogues hitherto reported for biosensing of UA.

Fabrication of a chitosan/glucose oxidase–poly(anilineboronic acid)–Aunano/Au-plated Au electrode for biosensor and biofuel cell

Enzyme immobilization is one of the key factors in constructing high-performance enzyme biosensors and biofuel cells (BFCs). Herein, we propose a new protocol for efficient immobilization of a glycoprotein enzyme based on the interaction of the 1, 2- or 1, 3-diols in the glycoprotein with a boronic acid functionalized monomer. Briefly, casting a mixture of glucose oxidase (GOx) and anilineboronic acid (ABA) followed by a NaAuCl4 solution to an Au-plated Au electrode surface yielded a GOx–poly(ABA) (PABA)–gold nanoparticle (Aunano) bionanocomposite, and chitosan (CS) was then cast and air-dried. In the present protocol, the small-sized Aunano or Au subnanostructures can form near/on the enzyme molecule, which greatly promotes the electron transfer of enzymatic reaction and enhances the amperometric responses. The thus-prepared CS/GOx–PABA–Aunano/Au-plated Au electrode worked well in the first-/second generation biosensing modes and as a bioanode in a monopolar biofuel cell, with analytical or cell-power performance superior to those of most analogues hitherto reported.

Charging of Self‐Doped Poly(Anilineboronic Acid) Films Studied by in Situ ESR/UV/Vis/NIR Spectroelectrochemistry and ex Situ FTIR Spectroscopy

Charge carriers: The p-doping of self-doped poly(anilineboronic acid) (PANI-BA) is studied by in situ electron spin resonance (ESR)/ultraviolet/visible/near-infrared (UV-vis-NIR) spectroelectrochemistry with respect to the role of the ionic side group at the aniline core (see figure). The results point to a primary polaron-pair formation while a polaron is formed with a further increase of the doping level. At higher doping levels, the formation of diamagnetic species is observed.

Synthesis of Poly(anilineboronic acid) Nanofibers for Electrochemical Detection of Glucose

Poly(anilineboronic acid) (PABA) nanofibers with U-shaped and ring-shaped morphologies have been synthesized successfully by chemical polymerization of 3-aminophenylboronic acid (APBA) in the presence of cetyltrimethylammonium bromide (CTAB) and NaF. The morphologies and sizes of PABA nanofibers can be controlled by adjusting the synthetic parameters, such as the concentrations of CTAB and APBA. The U-shaped PABA nanofibers exhibit excellent electrochemical redox activity and high sensitive detection of D-glucose in phosphate-buffered saline stock solution (pH 7.4) because of their high effective surface area as well as the high density of boronic acid groups.

Self-Doped Polyaniline Nanoparticle Dispersions Based on Boronic Acid−Phosphate Complexation

Poly(anilineboronic acid)/phosphate nanoparticle dispersions are produced in high yields using the reactivity of the boronic acid moiety with phosphate in the presence of fluoride. The poly(anilineboronic acid)/phosphate dispersions have been characterized using spectroscopic, microscopic and electrochemical techniques. According to 11 B NMR studies, the formation of anionic tetrahedral boronate group in phosphoric acid in the presence of fluoride forms the basis of self-doped, stabilized PABA nanoparticle dispersion. Transmission electron microscope images show that 25-50 nm diameter PABA nanoparticles are formed under these conditions. UV-vis, FT-IR-ATR spectroscopic and cyclic voltammetric results confirm the formation of the conducting form of PABA. Films produced from these particles exhibit enhanced redox stability and potential dependant conductivity under neutral and basic pH conditions due to the formation of a boron- phosphate complex containing fluoride, which results in a self-doped form of the polymer.

Conducting Poly(anilineboronic acid) Nanostructures: Controlled Synthesis and Characterization

AbstractSelf‐doped poly(anilineboronic acid) (PABA) nanostructures have been prepared by chemical polymerization in an aqueous acid solution and aliphatic alcohols. In aliphatic alcohols, PABA is soluble under the polymerization conditions. According to 11B NMR studies, the formation of anionic tetrahedral boronate ester in aliphatic alcohols in the presence of fluoride forms the basis of self‐doped, soluble PABA. Transmission electron microscope images show the formation of nanostructures with different shapes and forms in different solvents after precipitation of the polymer as a result of ion exchange in the presence of 0.5 M HCl. The spectroscopic and cyclic voltammetric results confirm the formation of conducting PABA nanostructures in high yield. The conductivity of PABA thin films made from the nanostructures prepared in aqueous acid, methanol, ethanol and 1‐propanol is approximately 15 and 3.0, 2.1 and 1.9 S · cm−1, respectively. The conducting PABA nanostructures are processable since they are easily re‐dispersed in the various solvents up to approximately 5 mg · mL−1. UV‐vis kinetic measurements, XPS and 11B NMR results suggest that the formation of various nanostructures is influenced by the polymerization rate, the degree of self‐doping versus external doping, and the polarity of the solvents used. The PABA nanostructured films produced from these structures exhibit enhanced redox stability in a wider potential window in non‐aqueous media compared to polyaniline due to formation of six‐member heterocyclic complexes containing a boron‐imine dative bond resulting in a self‐doped self‐cross‐linked polymer. The degree of crosslinking depends on the nature of nanostructures. In non‐aqueous media, the self‐doped, self‐cross‐linked PABA nanostructured films are much less susceptible to cathodic and anodic degradation at extreme potentials, overcoming a major limitation of more common conducting polymers.magnified image

Interference of Ascorbic Acid in the Sensitive Detection of Dopamine by a Nonoxidative Sensing Approach

The electrochemistry of a poly(anilineboronic acid)/carbon nanotube composite was studied in the presence of dopamine and ascorbic acid. To understand the binding affinity of dopamine and ascorbic acid to the boronic acid functional groups in the composite, the association constants between the diol groups in dopamine and ascorbic acid and the boronic acid were experimentally determined using a fluorescence-based binding assay. The results demonstrate that ascorbic acid could severely interfere with the detection of dopamine in nonoxidative boronic acid-binding approaches: Ascorbic acid was able to electrocatalytically reduce the fully oxidized polyaniline backbone during the electrochemical oxidation process; similarly to dopamine, ascorbic acid was also able to bind to the boronic acid groups through its planar diol group even though the binding affinity is much lower. The examination of the dopamine transduction mechanism and ascorbic acid interference mechanism in this nonoxidative approach will benefit the design of future boronic acid-based sensors.

A Nonoxidative Sensor Based on a Self-Doped Polyaniline/Carbon Nanotube Composite for Sensitive and Selective Detection of the Neurotransmitter Dopamine

Most of the current techniques for detection of dopamine exploit its ease of oxidation. However, the oxidative approaches suffer from a common problem. The products of dopamine oxidation can react with ascorbic acid present in samples and regenerate dopamine again, which severely limits the accuracy of detection. In this paper, we report a nonoxidative approach to electrochemically detect dopamine with high sensitivity and selectivity. This approach takes advantage of the high performance of our newly developed poly(anilineboronic acid)/carbon nanotube composite and the excellent permselectivity of the ion-exchange polymer Nafion. The binding of dopamine to the boronic acid groups of the polymer with large affinity affects the electrochemical properties of the polyaniline backbone, which act as the transduction mechanism of this nonoxidative dopamine sensor. The unique reduction capability and high conductivity of single-stranded DNA functionalized, single-walled carbon nanotubes greatly improved the electrochemical activity of the polymer in physiological buffer, and the large surface area of the carbon nanotubes largely increased the density of the boronic acid receptors. The high sensitivity along with the improved selectivity of this sensing approach is a significant step forward toward molecular diagnosis of Parkinson's disease.