Dual-targeted and controlled release delivery of doxorubicin to breast adenocarcinoma: In vitro and in vivo studies.

Doxorubicin (DOX) is a chemotherapeutic drug that belongs to the anthracyclines family. Cardiotoxicity is one of the main limiting factor of prescribing DOX. To reduce its side effects and enhance the drug delivery to the targeted tissues, we aimed to establish a new targeted and controlled release drug delivery system for treatment of breast cancer. In this article, we tried to synthesize a new nanoplatform consisted of DOX conjugate with hydrazide and disulfide bonds to the hyaluronic acid (HA). Firstly, 4,4'-Dithiodibutyric acid (DTBH) was conjugated with HA. Then, 3-aminophenyl boronic acid monohydrate (APBA) was conjugated with DTBH-HA. Subsequently, DOX was added to DTBH-HA-APBA. HA is a natural polymer with the ability to target CD44, a cell surface adhesion receptor, which are highly overexpressed on the surface of variety of cancer cells. Other targeting agent, APBA can target sialic acid on the cancer cells surface and improve the tumor uptake. Formation of The DTBH-HA-APBA conjugate was confirmed by proton nuclear magnetic resonance (1H NMR) spectroscopy. Scanning emission electron microscopy (SEM) images of the DOX-DTBH-HA-APBA displayed a spherical shape with an average diameter of about 70 nm. In vitro drug release study showed considerably different release pattern of DOX from the formulation at acidic pH (5.4) which was higher than normal pH (7.4). Cellular uptake and cellular cytotoxicity analysis were examined in human breast adenocarcinoma cell line (MCF-7) and mouse breast cancer cells (4T1) as positive cell lines and Chinese Hamster Ovary cells (CHO) as negative cell line. Results confirmed that there is a remarkable difference between dual-targeted (DOX-DTBH-HA-APBA) and single targeted (DOX-DTBH-HA) formulations in both positive cell lines regarding internalization and cytotoxicity. In vivo studies indicated that dual-targeted formulation has the best efficacy with minimum side effects in mouse model. Fluorescence imaging of organs revealed that DOX-DTBH-HA-APBA showed greater DOX accumulation compared with DOX-DTBH-HA and free DOX in tumor site. Also, pathological evaluation indicated that there is no observable cardiotoxicity with final formulation.

3-Aminophenyl Boronic Acid Functionalized Quantum-Dot-Based Ratiometric Fluorescence Sensor for the Highly Sensitive Detection of Tyrosinase Activity.

Using the commercially available and economical 6-hydroxycoumarin (6-HC) as the substrate, a dual-emission ratiometric fluorescence sensor was developed to detect tyrosinase (TYR) activity based on 3-aminophenyl boronic acid functionalized quantum dots (APBA-QDs). TYR can catalyze 6-HC, a monohydroxy compound, to form a fluorescence-enhancing o-hydroxy compound, 6,7-dihydroxycoumarin. Owing to the special covalent binding between the o-hydroxyl and boric acid groups, APBA-QDs react with 6,7-dihydroxycoumarin to form a five-membered ring ester dual-emission fluorescence probe for TYR. With an increase in TYR activity, the fluorescence at 675 nm originating from the QDs is gradually quenched, whereas that at 465 nm owing to 6,7-dihydroxycoumarin increases. Referencing the decreasing signal of the dual-emission probe at 675 nm to measure the increasing signal at 465 nm, a ratiometric fluorescence method was established to detect the TYR activity with high sensitivity and selectivity. Under the conditions optimized via response surface methodology, a linear range of 0-0.05 U/mL was obtained for the TYR activity. The detection limit was as low as 0.003 U/mL. This sensing strategy can also be adopted for the rapid screening of the TYR inhibitors.

Synthesis and characterization of novel poly(3-aminophenyl boronic acid-co-vinyl alcohol) nanocomposite polymer stabilized silver nanoparticles with antibacterial and antioxidant applications.

In this work, the synthesis method and applications of nanocomposite polymer stabilized silver nanoparticles (AgNPs) are reported. 3-Aminophenyl boronic acid (3APBA) was used as a reductant of silver nitrate which acted as an oxidant for the polymerization of 3APBA through in situ chemical oxidative polymerization to poly(3-aminophenyl boronic acid) or PABA. The formation of PABA in the reaction mixture led to particle agglomeration owing to PABA poor solubility. However, in the presence of hydrophilic poly(vinyl alcohol) (PVA), PABA binds to the free hydroxyl group of PVA to form a composite polymer (PABA-PVA), which perfectly stabilized the formed AgNPs. Succinctly, PVA acted as a solubilizer and stabilizer for (PABA-PVA)AgNPs synthesis. Synthesis was optimized and sharp absorption peaks at 290 nm and 426 nm were observed, attributing to the π-π* transition of the benzenoid ring of PABA and the characteristic absorption spectrum of AgNPs, respectively. (PABA-PVA)AgNPs was characterized using UV-vis, TEM, FESEM, EDX, XRD, FTIR, TGA/DTG, DLS and zeta potential analysis. In addition, the antibacterial, antioxidant and metal chelating capacities of (PABA-PVA)AgNPs were evaluated. The (PABA-PVA)AgNPs exhibited significant antibacterial activity against Escherichia coli and Listeria monocytogenes, and good antioxidant and metal chelating properties of (PABA-PVA)AgNPs, thus validating its attractive biological applications.

Colorimetric determination of sialic acid based on boronic acid-mediated aggregation of gold nanoparticles.

The authors describe a rapid, sensitive and selective colorimetric assay for sialic acid (SA) based on the use of gold nanoparticles (AuNPs) modified with 3-aminophenylboronic acid (3-APBA) which acts as the recognition probe for SA. 3-APBA contains amino groups and boronic acid groups through which it can assemble on citrate stabilized AuNPs. It reacts with the cis-diol groups of SA by reversible formation of a cyclic boronate ester in slightly acidic buffer. Detection involves the sequential addition of AuNPs, phosphate buffer, 3-APBA and SA in a tube, vortex mixing, acquisition of photographic images or absorption spectra, and calculation of the result. The method is simple, rapid, and does not require cumbersome steps such as the preparation of stable boronic acid functionalized AuNPs as used in colorimetric sensing of saccharides. Under the optimum conditions, the ratio of absorbances at 700 and 520 nm increases linearly in the 0.15-1.00 mM SA concentrations range, and the detection limit is 60 µM. This is comparable to the detection limit obtained in other colorimetric assays reported. Acceptable intra- and inter-day precisions of three SA concentrations (0.50, 1.00 and 2.00 mM) ranged from 1.9-4.2% and 4.2-6.4%, respectively. The efficacy of the method was demonstrated by analyzing simulated human saliva which gave recoveries ranging from 98.7-106.0%. Graphical abstract Schematic of a colorimetric method for detection of sialic acid (SA) in simulated saliva. It is based on aggregation of gold nanoparticles with 3-aminophenyl boronic acid (3-APBA) which assembles on AuNPs while the boronic acid group binds to cis-diols of SA to form a boronate ester.

Label- and enzyme-free detection of glucose by boronic acid-coupled poly(styrene-b-acrylic acid) at liquid crystal/aqueous interfaces.

A glucose biosensor was developed based on a 4-cyano-4'-pentylbiphenyl (5CB)-filled transmission electron microscopy (TEM) grid cell by coating poly (styrene-b-acrylic acid) (PS-b-PAA) at the 5CB/aqueous interface and immobilising 3-aminophenyl boronic acid (APBA) on the PAA block chains by N-(3-dimethylaminopropyl)-N-ethylcarbodiimide coupling. Binding events between APBA and glucose were translated into homeotropic-to-planar configurational changes of 5CB, which were observed by polarised optical microscopy (POM) under crossed polarisers. This liquid-crystal-based glucose biosensor exhibited high sensitivity (limit of detection: 0.1 mM), even in complex serum and urine samples, high selectivity (against cholesterol, haemoglobin, and urea), and good stability for 40 d. This new and sensitive glucose biosensor has the advantages of low production cost, a simple immobilisation technique, and easy detection with POM, and may be useful for pre-screening glucose levels in human samples (serum and urine).

A selective glucose sensor based on direct oxidation on a bimetal catalyst with a molecular imprinted polymer.

A selective nonenzymatic glucose sensor was developed based on the direct oxidation of glucose on hierarchical CuCo bimetal-coated with a glucose-imprinted polymer (GIP). Glucose was introduced into the GIP composed of Nafion and polyurethane along with aminophenyl boronic acid (APBA), which was formed on the bimetal electrode formed on a screen-printed electrode. The extraction of glucose from the GIP allowed for the selective permeation of glucose into the bimetal electrode surface for oxidation. The GIP-coated bimetal sensor probe was characterized using electrochemical and surface analytical methods. The GIP layer coated on the NaOH pre-treated bimetal electrode exhibited a dynamic range between 1.0µM and 25.0mM with a detection limit of 0.65±0.10µM in phosphate buffer solution (pH 7.4). The anodic responses of uric acid, acetaminophen, dopamine, ascorbic acid, L-cysteine, and other saccharides (monosaccharides: galactose, mannose, fructose, and xylose; disaccharides: sucrose, lactose, and maltose) were not detected using the GIP-coated bimetal sensor. The reliability of the sensor was evaluated by the determination of glucose in artificial and whole blood samples.

An impedimetric biosensor for the diagnosis of renal cell carcinoma based on the interaction between 3-aminophenyl boronic acid and sialic acid.

Renal cell carcinoma (RCC) often expresses a high density of sialic acid-rich glycoproteins which helps these late-stage cancer cells to enter the blood stream or urine. Blood diagnosis is a complex and time-consuming process. In this study, we developed a facile and non-invasive electrochemical cytosensor for early detection of RCC in urine samples based on specific recognition by 3-aminophenyl boronic acid (APBA). Polypyrrole (PPy) and bovine serum albumin (BSA)-incorporated Ag submicron particles (Ag@BSA) were co-deposited on a gold electrode (GE) to take advantages of the excellent properties of these biomaterials, including good biocompatibility, low cytotoxicity and excellent electro-conductivity. To further increase the biosensor's sensitivity, APBA molecules were integrated to recognize sialic acid (SA) on the cell surface. Under optimal conditions, the impedimetric cytosensor exhibited a good linear relationship with the logarithm of the cell concentration from 17 to 1.7×106 cellsmL-1, and the low detection limit was 6 cellsmL-1 (S/N=3). Therefore, the electrochemical impedimetric biosensor offers a potential approach to bedside rapid detection of RCC in clinical applications.

A potentiometric non-enzymatic glucose sensor using a molecularly imprinted layer bonded on a conducting polymer.

A non-enzymatic potentiometric glucose sensor for the determination of glucose in the micomolar level in saliva was developed based on a molecularly imprinted polymer (MIP) binding on a conducting polymer layer. A MIP containing acrylamide, and aminophenyl boronic acid, as a host molecule to glucose, was immobilized on benzoic acid-functionalized poly(terthiophene) (pTBA) by the amide bond formation onto a gold nanoparticles deposited-screen printed carbon electrode (pTBA/AuNPs/SPCE). Aromatic boronic acid was incorporated into the MIP layer to stably capture glucose and create a potentiometric signal through the changed pKa value of polymer film by the formation of boronate anion-glucose complex with generation of H+ ions by the cis-diol reaction. Reversible binding and extraction of glucose on the sensor surface was observed using a quartz crystal microbalance. Each layer of the sensor probe was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The potentiometric response at the optimized conditions exhibited a wide linear dynamic range of 3.2×10-7 to 1.0×10-3M, with a detection limit of 1.9 (±0.15)×10-7M. The sensor probe revealed an excellent selectivity and sensitivity for glucose compared to other saccharides. In addition, the reliability of the proposed glucose sensor was evaluated in physiological fluid samples of saliva and finger prick blood.

Validação do teste de inibição pelo ácido aminofenilborônico para triagem de Klebsiella pneumoniae carbapenemases (KPC) / Validation of inhibition test by aminophenyl boronic acid to Klebsiella pneumoniae carbapenemases (KPC) screening

INTRODUÇÃO: A produção de enzimas Klebsiella pneumoniae carbapenemase (KPC) tem se tornado um importante e preocupante mecanismo de resistência, e ensaios que combinem alta sensibilidade e alta especificidade para a detecção dessas enzimas são escassos. OBJETIVO: Validar o teste de inibição pelo ácido 3-aminofenilborônico como método de triagem fenotípica de cepas produtoras de enzima KPC, comparando os resultados obtidos com os de testes confirmatórios por reação em cadeia da polimerase (PCR). METODOLOGIA: Avaliou-se o uso do ácido 3-aminofenilborônico impregnado em discos de antibióticos de imipenem, meropenem e ertapenem. Foram testadas 36 cepas positivas e 12 negativas, todas confirmadas por PCR. Foram ainda testadas três concentrações diferentes de ácido borônico: 300, 400 e 600 µg. RESULTADOS: Entre as cepas positivas testadas, o resultado mais adequado se deu com a adição do composto em disco contendo ertapenem, com especificidade de 100%, porém com sensibilidade de apenas 50%. CONCLUSÃO: Novos estudos são necessários, sobretudo no que diz respeito à padronização da técnica e aos insumos utilizados, pois o método se revela promissor na triagem de cepas produtoras de KPC.

INTRODUCTION: The production of Klebsiella pneumoniae carbapenemases enzymes (KPC) has become an important and worrisome resistance mechanism. Furthermore, tests that combine high sensitivity and high specificity for the detection of these enzymes are scarce. OBJECTIVE: To validate the inhibition test by 3-aminophenyl boronic acid as a phenotypic screening method for KPC-producing strains by comparing the results with confirmatory polymerase chain reaction testing (PCR). METHODS: We evaluated the use of 3-aminophenyl boronic acid applied on disks with imipenem, meropenem and ertapenem antibiotics. 36 strains were positive and 12 were negative, all confirmed by PCR. Three different concentrations of boronic acid were also tested: 300, 400 and 600 µg. RESULTS: Among the positive strains, the results were more accurate with the addition of the compound to the ertapenem disk, presenting 100 % specificity and 50% sensitivity. CONCLUSION: Further studies are required, mainly regarding the standardization of the technique and materials, since the method seems to be promising as to the screening of KPC strains.