Benzenesulfonic acid

Quantification of residual AEBSF-related impurities by reversed-phase liquid chromatography.[Pubmed:30953918]

J Chromatogr B Analyt Technol Biomed Life Sci. 2019 Mar 20;1116:19-23.

During research of a broadly neutralizing antibody (bNAb) for HIV-1 infection, site-specific clipping was observed during cell culture incubation. Protease inhibitor, 4-(2-aminoethyl) benzenesulfonyl fluoride (AEBSF), was supplemented to the cell culture feeding to mitigate clipping as one of the control strategies. It led to the need and development of a new assay to monitor the free AEBSF-related impurities during the purification process. In this work, a reversed-phase liquid chromatography (RPLC-UV) method was developed to measure the total concentration of AEBSF and its major degradant product, 4-(aminoethyl) Benzenesulfonic acid (AEBS-OH). This quantitative approach involved hydrolysis pre-treatment to drive all AEBSF to AEBS-OH, a filtration step to remove large molecules, followed by RPLC-UV analysis. The method was qualified and shown to be capable of measuring AEBS-OH down to 0.5muM with good accuracy and precision, which was then applied for process clearance studies. The results demonstrated that a Protein A purification step in conjunction with a mock ultrafiltration/diafiltration (UF/DF) step could remove AEBSF-related impurities below the detection level. Overall, this study is the first to provide a unique approach for monitoring the clearance of free AEBSF and its related degradant, AEBS-OH, in support of the bNAb research.

Understanding the performance of a paper-based UV exposure sensor: The photodegradation mechanism of brilliant blue FCF in the presence of TiO2 photocatalysts in both the solid-state and solution.[Pubmed:30900784]

Rapid Commun Mass Spectrom. 2019 Mar 22.

RATIONALE: The decolouration of brilliant blue FCF by the action of TiO2 under UV exposure has been recently reported as the basis of a paper-based sensor for monitoring UV sun exposure. The mechanism of brilliant blue FCF photodegradation in the presence of the photocatalyst and the resulting photoproducts are thus far unknown. METHODS: The UV initiated photodegradation of brilliant blue FCF in the presence of TiO2 for both the aqueous and the solid state was investigated. Degradation in the solid state was observed using matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-MS). Decomposition of the dye in the aqueous state was analysed using liquid chromatography mass spectrometry (LC/MS) and ultraviolet-visible (UV-Vis) spectroscopy. RESULTS: After UV radiation exposure, the brilliant blue FCF base peak [M1-H+NH4 ](+) (m/z calc. 766.194 found 766.194) decreased in the LC/MS chromatogram with a concomitant appearance of BB-FCF decomposition products involving the sequential loss of the N-ethyl and N-methylbenzene sulfonate (MBSA) groups, assigned as [M2+H](+) (-MBSA, calc. 579.163 found 579.162), [M3+H](+) (-MBSA, -Et, calc. 551.131 found 551.131), [M4+H](+) (-2MBSA, calc. 409.158 found 409.158), [M5+H](+) (-2MBSA, -Et, calc. 381.127 found 381.127). Ions [M2+H](+) and [M3+H](+) were also identified in the photodegradation products using MALDI-MS. Observation by UV-vis indicated a decrease in the solution absorbance maxima and an associated blue-shift upon UV exposure in solution. CONCLUSION: The LC/MS analysis indicated two main oxidation processes. The most obvious was attack of the N-methylene, eliminating either ethyl or MBSA groups. The presence of the hydroxylated decomposition product M13 ([M13+H](+) calc. 595.157, found 595.157) supported this assignment. In addition, the detection of photoproduct M8, proposed to be 3-((ethylamino)methyl)Benzenesulfonic acid ([M8+H](+) calc. 216.069 found 216.069), indicates an aryl-oxidative elimination. The absence of the aryl-hydroxy products normally expected to accompany the formation of M8 is proposed to be due to TiO2 binding catechol-like derivatives, which are then removed upon filtration.

Electrodeposition of 4-Benzenesulfonic Acid onto a Graphite-Epoxy Composite Electrode for the Enhanced Voltammetric Determination of Caffeine in Beverages.[Pubmed:30809415]

J Anal Methods Chem. 2019 Jan 23;2019:8596484.

Caffeine is widely present in food and drinks, such as teas and coffees, being also part of some currently commercialized medicines, but despite its enhancement on several functions of human body, its exceeding use can promote many health problems. In order to develop new fast approaches for the caffeine sensing, graphite-epoxy composite electrodes (GECE) were used as substrate, being modified by different diazonium salts, synthetized as their tetraflouroborate salts. An analytical method for caffeine quantification was developed, using sware wave voltammetry (SWV) in Britton-Robinson buffer pH 2.0. Detection limits for bare electrode and 4-benzenesulfonic modified electrode were observed circa 145 micromol.L(-1) and 1.3 micromol.L(-1), respectively. The results have shown that the modification shifts the oxidation peaks to lower potential. Kinetics of the reaction limited by diffusion was more expressive when caffeine was added to the solution, resulting in decreases of impedance, characterized by lower R ct. All results for caffeine determination were compared to a reference chromatographic procedure (HPLC), showing no statistical difference. Analytical parameters for validation were suitably determined according to local legislation, leading to a linear behaviour from 5 to 150 micromol.L(-1); precision of 4.09% was evaluated based on the RDC 166/17, and accuracy was evaluated in comparison with the reference method, with recovery of 98.37 +/- 2.58%.

A photoresponsive molecularly imprinted polymer with rapid visible-light-induced photoswitching for 4-ethylphenol in red wine.[Pubmed:30606579]

Mater Sci Eng C Mater Biol Appl. 2019 Mar;96:661-668.

The trans to cis isomerization of the azobenzene chromophore in most azobenzene-based photoresponsive molecularly imprinted polymers (MIPs) is initiated by UV irradiation. This limits the application of these materials in cases where UV light toxicity is an issue, such as in biological systems, food monitoring, and drug delivery. Herein we report a tetra-ortho-methyl substituted azobenzene, (4-[(4-methacryloyloxy)-2,6-dimethyl phenylazo]-3,5-dimethyl Benzenesulfonic acid (MADPADSA). The photoswitching of MADPADSA could be induced by visible-light irradiation (550nm for trans to cis and 475nm for cis to trans) in 4-hydroxyethylpiperazineethanesulfonic acid (HEPES) buffer-ethanol (4:1, v/v) at pH7.0, however, the photoisomerization was slow. With the use of MADPADSA as a functional monomer, NaYF4:Yb(3+),Er(3+) as a substrate, 4-ethylphenol (4-EP) as a template, a novel photoresponsive surface molecularly imprinted polymer NaYF4:Yb(3+),Er(3+)@MIP was obtained. The NaYF4:Yb(3+),Er(3+)@MIP displayed rapid visible-light-induced photoswitching. The NaYF4:Yb(3+),Er(3+) substrate could efficiently increase the trans to cis isomerization rate of the photoresponsive MIP on its surface, which was faster than that of the corresponding azobenzene monomer MADPADSA. Possible reasons for this effect were investigated by fluorescence spectroscopy. NaYF4:Yb(3+),Er(3+)@MIP displayed good specificity toward 4-EP with a specific binding constant (Kd) of 3.67x10(-6)molL(-1) and an apparent maximum adsorption capacity (Qmax) of 10.73mumolg(-1), respectively. NaYF4:Yb(3+),Er(3+)@MIP was applied to determine the concentration of 4-EP in red wine with good efficiency and a limit of detection lower than the value that could cause an unpleasant off-flavor.

Decomposition of 15 aromatic compounds in supercritical water oxidation.[Pubmed:30476770]

Chemosphere. 2019 Mar;218:384-390.

Supercritical water oxidation (SCWO) of 15 aromatic compounds, including bisphenol A (BPA), nonylphenol (NP) and octylphenol (OP), was investigated under temperature and reaction time ranged of 350-550 degrees C and 0.5-6min, respectively, with 300% excess oxygen, resulted in the degradation rate constants of total organic carbon (kTOC) were 0.130-0.392 min(-1). To further explore the relationship between TOC removal and molecular characteristics, density functional theory (DFT) method had been used to calculate the quantum descriptors of the 15 aromatic compounds. The result of correlation analysis showed that the most positive partial charge on the H atom, namely q(H)x, played a significant role in TOC removal, which implied the more q(H)x value was, the easier H atom could lose, resulted in higher kTOC constant. Different substituent groups in the phenyl ring could lead to different TOC removal efficiencies. It presented that the more F(0) value was, the more easily to be attacked by radicals, as a result, the kTOC followed the order that Benzenesulfonic acid (BSA)>phenol>methylbenzene (MB)>3-phenylpropionic acid (3-PPA), as well as BPA

Dicopper(I) Complexes Incorporating Acetylide-Functionalized Pyridinyl-Based Ligands: Synthesis, Structural, and Photovoltaic Studies.[Pubmed:30222331]

Inorg Chem. 2018 Oct 1;57(19):12113-12124.

Heteroaryl incorporated acetylide-functionalized pyridinyl ligands (L1-L6) with the general formula Py-C identical withC-Ar (Py = pyridine and Ar = thiophene-2-yl, 2,2' -bithiophene]-5-yl, 2,2' :5',2'' -terthiophene]-5-yl, thieno[2,3- b]thiophen-2-yl, quinoline-5-yl, benzo[c][1,2,5]thiadiazole-5-yl) have been synthesized by Pd(0)/Cu(I)-catalyzed cross-coupling reaction of 4-ethynylpyridine and the respective heteroaryl halide. Ligands L1-L6 were isolated in respectable yields and characterized by microanalysis, IR spectroscopy, (1)H NMR spectroscopy, and ESI-MS mass spectrometry. A series of dinuclear Cu(I) complexes 1-10 have been synthesized by reacting L1-L6 with CuI and triphenylphosphine (PPh3) (R1) or with an anchored phosphine derivative, 4-(diphenylphosphino) benzoic acid (R2)/2-(diphenylphosphino)Benzenesulfonic acid (R3), in a stoichiometric ratio. The complexes are soluble in common organic solvents and have been characterized by analytical, spectroscopic, and computational methods. Single-crystal X-ray structure analysis confirmed rhomboid dimeric structures for complexes 1, 2, 4, and 5, and a polymeric structure for 6. Complexes 1-6 showed oxidation potential responses close to 0.9 V vs Fc(0/+), which were chemically irreversible and are likely to be associated with multiple steps and core oxidation. Preliminary photovoltaic (PV) results of these new materials indicated moderate power conversion efficiency (PCE) in the range of 0.15-1.56% in dye-sensitized solar cells (DSSCs). The highest PCE was achieved with complex 10 bearing the sulfonic acid anchoring functionality.

A photoresponsive surface molecularly imprinted polymer shell for determination of trace griseofulvin in milk.[Pubmed:30184762]

Mater Sci Eng C Mater Biol Appl. 2018 Nov 1;92:365-373.

A new photoresponsive surface molecularly imprinted polymer shell (PMIPS) was developed for determination of trace griseofulvin from milk. The PMIPS was prepared by surface imprinting technique using poly(styrene-co-methacrylic acid) (PS-co-PMMA) microspheres as the sacrificial substrate, griseofulvin as the template, a photoresponsive azobenzene derivative 4-((4-(methacryloyloxy)phenyl)diazenyl)-3,5-dimethyl Benzenesulfonic acid as the functional monomer, and triethanolamine trimethacrylate as the cross-linker. The PMIPS was obtained after the removal of the sacrificial PS-co-PMMA core from the surface imprinted core-shell microspheres, PS-co-PMAA@PMIP. Compared with PS-co-PMAA@PMIP, PMIPS displayed better properties such as higher surface area and pore volume, rapid photo-isomerization rate, and higher adsorption capacities, specific binding constant and binding density. The PMIPS could efficiently detect griseofulvin in complex samples such as milk.

Microwave-Assisted Rapid Preparation of Mesoporous Phenolic Resin Nanospheres toward Highly Efficient Solid Acid Catalysts.[Pubmed:30086220]

ACS Appl Mater Interfaces. 2018 Aug 29;10(34):28709-28718.

A novel microwave-assisted polymerization and self-assembly protocol was developed to prepare ordered mesoporous phenolic resin (MPRN) with nanospherical morphology for the first time. This unique strategy dramatically saved the synthesis time about 2 days with an energy-efficient way. Owing to its abundant phenyl groups in the framework, it was easily transformed to Benzenesulfonic acid-functionalized MPRN (SO3H-MPRN) by simple sulfonation treatment. The obtained SO3H-MPRN sample still possessed a large surface area, two-dimensional hexagonal mesoporous structure, and uniform spherical shape. Importantly, because of its intrinsic organic framework, the pore surface of SO3H-MPRN was hydrophobic. Accordingly, it exhibited the excellent catalytic activity and selectivity in aqueous formaldehyde-participated Prins reaction and water-medium Fischer-indole reaction. On the basis of material characterizations and the control experiments, this remarkable catalytic performance could be ascribed to the synergetic effect derived from its short mesoporous channel and hydrophobic pore surface, which resulted in the decreased reactant diffusion limitation and the reduced water competitive adsorption. Also, it was stable in water because of the periodically arranged acid species in the resin framework and thus was easily recycled and used repetitively for at least five times.

Aging-Resistant Functionalized LDH(-)SAS/Nitrile-Butadiene Rubber Composites: Preparation and Study of Aging Kinetics/Anti-Aging Mechanism.[Pubmed:29783656]

Materials (Basel). 2018 May 18;11(5). pii: ma11050836.

With the aim of improving the anti-aging properties of nitrile-butadiene rubber (NBR), a functional organic filler, namely LDH(-)SAS, prepared by intercalating 4-amino-Benzenesulfonic acid monosodium salt (SAS) into layered double hydroxides (LDHs) through anion exchange, was added to nitrile-butadiene rubber (NBR), giving the NBR/LDH(-)SAS composites. Successful preparation of LDH(-)SAS was confirmed by XRD, TGA and FTIR. LDH(-)SAS was well dispersed in the NBR matrix, owing to its strong interaction with the nitrile group of NBR. The obtained NBR/LDH(-)SAS composites exhibited excellent thermo-oxidative aging resistance as shown by TGA-DSC. Further investigation by ATR-FTIR indicated that SAS can capture the radical groups, even during the aging process, which largely accounts for the improved aging resistance.

Evaluation of In vitro and In vivo Drug Efficacy Over Leishmania tropica: A Pilot Study.[Pubmed:29780014]

Turkiye Parazitol Derg. 2018 Mar;42(1):11-19.

OBJECTIVE: Two pentavalent antimonials, meglumine antimoniate (Glucantime(R), France) and sodium stibogluconate (Pentostam(R), England), are used to treat cutaneous leishmaniasis (CL) in Turkey. The present study, serving as a guidebook for young researchers, aims to provide basis for conducting drug resistance tests and active ingredient scanning in in vitro and in vivo models. METHODS: A CL isolate kept in liquid nitrogen was initially thawed and genotyped by real-time polymerase chain reaction (PCR) using ITS1 prob. In vitro and in vivo tests were conducted to determine drug resistance against meglumine antimoniate and sodium stibogluconate. Hemocytometry and XTT (sodium 3,39-[1-(phenylaminocarbonyl)-3,4-tetrazolium]-bis (4-methoxy-6-nitro) Benzenesulfonic acid hydrate) methods were used to investigate in vitro drug resistance. CL mouse models were used to analyze in vivo drug resistance. RESULTS: The isolate was determined as Leishmania tropica by genotyping by PCR on the internal transcribed spacer 1 (ITS1) gene region. In in vitro drug resistance tests, sodium stibogluconate was observed to be more effective than meglumine antimoniate, but there was no statistically significant difference between the two (p > 0.05). It was observed that the footpad lesions of the animals started to shrink afterward the 5th week of infection following treatment with these agents, and parasitologic recovery was observed at the end of 3 months. CONCLUSIONS: With an aim to be used as a guidebook for young researchers, active ingredient scanning and drug resistance tests in both in vitro and in vivo models were presented in the current study.

Hydrolysis-Kinetic Study of AEBSF, a Protease Inhibitor Used during Cell-Culture Processing of the HIV-1 Broadly Neutralizing Antibody CAP256-VRC25.26.[Pubmed:29508618]

Anal Chem. 2018 Apr 3;90(7):4293-4296.

One approach to mitigate product clipping during HIV mAb CAP256-VRC26.25 cell-culture development is the addition of the protease inhibitor 4-(2-aminoethyl) benzenesulfonyl fluoride (AEBSF) to the cell-culture media. AEBSF can undergo hydrolysis to form an inactive compound, 4-(2-aminoethyl) Benzenesulfonic acid. Using mass-spectrometry detection, a kinetic profile of AEBSF hydrolysis was generated for conditions simulating those of cell culture at pH 7.0 and 37 degrees C. It was found that increasing the pH or the temperature could accelerate AEBSF hydrolysis. The kinetic-study results in this report provide an analytical characterization and guidance when optimizing an AEBSF-addition strategy for product-clipping control during cell-culture development and offer an alternative approach for AEBSF-related clearance studies post protein production.

Discovery of a Novel Polyfluoroalkyl Benzenesulfonic Acid around Oilfields in Northern China.[Pubmed:29218982]

Environ Sci Technol. 2017 Dec 19;51(24):14173-14181.

The existence of more than 3000 per- and polyfluoroalkyl substances (PFASs) on the global market has prompted the identification and hazard characterization of hitherto unknown PFASs. In the present study, a novel PFAS, sodium p-perfluorous nonenoxybenzenesulfonate (OBS), was identified using Orbitrap MS/MS in water samples around a suspected application area, Daqing Oilfield, China. The peak OBS concentration was 3.2 x 10(3) ng/L in a sample taken near the oil well with the longest production history in Daqing. The concentrations of OBS and contribution to the sum of PFASs in surface waters displayed considerable variation among the three sampling areas (mean levels at 6.9, 50, and 5.6 x 10(2) ng/L with mean percentages at 9.8%, 45%, and 69% in the background, new and old oilfield areas respectively) confirming that the density of oil wells and the oil production history are important factors influencing OBS contamination in the studied areas. A preliminary assessment of acute toxicity and environmental fate indicates that OBS exhibits similar toxicity and environmental persistence to perfluorooctanesulfonic acid (PFOS). The widespread occurrence of OBS, in conjunction with its potential hazard properties, underscores the need to further study on the bioaccumulation and potential for human exposure.