COVID-19,a disease caused by the novel coronavirus SARS-Co V-2,has produced a serious emergency for global public health,placing enormous stress on national health systems in many countries.Several studies suggest tha...COVID-19,a disease caused by the novel coronavirus SARS-Co V-2,has produced a serious emergency for global public health,placing enormous stress on national health systems in many countries.Several studies suggest that cytokine storms(interleukins)may play an important role in severe cases of COVID-19.Neutralizing key inflammatory factors in cytokine release syndrome(CRS)could therefore be of great value in reducing the mortality rate.Tocilizumab(TCZ)in its intravenous(IV)form of administration-Ro Actemra?20 mg/m L(Roche)-is indicated for treatment of severe CRS patients.Preliminary investigations have concluded that inhibition of IL-6 with TCZ appears to be efficacious and safe,with several ongoing clinical trials.This has led to a huge increase in demand for IV TCZ for treating severe COVID-19 patients in hospitals,which has resulted in drug shortages.Here,we present a comparability study assessing the main critical physicochemical attributes of TCZ solutions used for infusion,at 6 mg/m L and 4 mg/m L,prepared from Ro Actemra?20 mg/m L(IV form)and from Ro Actemra?162 mg(0.9 m L solution pre-filled syringe,subcutaneous(SC)form),to evaluate the use of the latter for preparing clinical solutions required for IV administration,so that in a situation of shortage of the IV medicine,the SC form could be used to prepare the solutions for IV delivery of TCZ.It is important to remember that during the current pandemic all the medicines are used off-label,since none of them has yet been approved for the treatment of COVID-19.展开更多
Baicalin,a major flavonoid compound found in Scutellariae radix,is the first SARS-CoV-23CLpro virus inhibitor.Therefore,developing an accurate and reliable strategy to detect baicalin in biological systems is vital.He...Baicalin,a major flavonoid compound found in Scutellariae radix,is the first SARS-CoV-23CLpro virus inhibitor.Therefore,developing an accurate and reliable strategy to detect baicalin in biological systems is vital.Herein,we report the first indolyl-lanthanide metal-organic framework(MOF)materials and their application as baicalin sensors.The results of this study indicate that the new crystal structure has good stability and luminous performance.The detection limits of baicalin in serum and urine are 0.05 and 0.04μmol/L,respectively,suggesting high sensitivity and selectivity.Various background substances present in practical samples,such as anions,cations,and amino acids,do not interfere with the photoluminescence analytical signal of Eu^(3+).We identified that the quenching of the Eu-MOF is due to the inner filter effect,absorption energy competition,and photoinduced electron transfer among the baicalin,ligand,and MOF through powder X-ray diffraction analysis,Fourier transform infrared spectroscopy,luminescence lifetimes,ultraviolet studies,and computational analysis.Thus,we designed a convenient,sensitive,and facile detection method using the Eu-MOF and demonstrate that Eu^(3+)-based materials are promising sensors for baicalin detection in actual serum and urine.Additionally,the prepared Eu-MOF@polyvinyl alcohol composite matrix membrane test film has considerable practical application value for the portable detection of baicalin.展开更多
Dill(Anethum graveolens),an annual species,was used to study the impact of metallic pollution potentially spreading fromthe nickel smelter dump in Dolna Streda(Slovakia)by monitoring 55 elements.Despite the proximity ...Dill(Anethum graveolens),an annual species,was used to study the impact of metallic pollution potentially spreading fromthe nickel smelter dump in Dolna Streda(Slovakia)by monitoring 55 elements.Despite the proximity of this dump(1 km),only soil Ni(54.8 mg/kg)or Pb(47.3 mg/kg),but not Cr,Mn,Fe or Co(main elements of the dump’s sludge)was elevated in given garden soil compared to two control sites.Mainly flowers and/or leaves contained significantly higher amounts of Ni,Cr,Pb,Cu,As,Sb,Sn,V,W,and some rare earth elements at the site close to the dump.Correlation between elements in organs and soil was significant mainly in stem or root but the bioaccumulation factor was typically low(<0.02)for most elements.A positive finding was that the 2022/2024 comparison revealed a decline in most elements in dill leaves,even at the dump site,which may reflect a decrease in the content of air PM particles.Soluble phenols were less accumulated in plants close to the nickel smelter dump,but flavonols showed the opposite trend,and free amino acids were positively correlated with many elements in the stem and root.An evaluation of commercial dill samples revealed variability(e.g.,up to 0.7 mg Cd/kg dry weight)but subsequent NCA and PCA analyses clearly separated the dump locality from other samples.However,significant differences in the content of Cd,Ni,Pb,As,and other elements encourage precise control of commercially available dill dry matter.展开更多
Hibiscus sabdarrifa flowers are known the world over. In Cote d’Ivoire, they are commonly known as “bissap” and are of great interest to local people, who use them to make an eponymous herbal tea. This drink has po...Hibiscus sabdarrifa flowers are known the world over. In Cote d’Ivoire, they are commonly known as “bissap” and are of great interest to local people, who use them to make an eponymous herbal tea. This drink has potential medicinal and nutritional value (Khan et al., 2022). Nine (9) samples of dried flowers of the plant, packaged in 3 g sachets of a local Kuinafo brand, were used for physico-chemical analyses. Heavy metals, mineral salts, ash and moisture content were determined using methods adapted from the Association of Official Analytical Chemists (AOAC). The results showed the presence of heavy metals at levels whose intake should take into account the weight of the consumer in the case of mercury and arsenic (0.5 mg/Kg and 0.7 mg/Kg respectively). Apart from lead, whose level was not compliant (1.310 mg/Kg for a CSHPF standard of 0.5 mg/Kg), cadmium had a regulatory level (0.18 mg/Kg for a CSHPF standard of 0.20 mg/Kg). Nutrient intakes were significant (calcium, iron and potassium respectively at 1.79 g/100g;17.27 mg/100g and 1.76 g/100g of dried Hibiscus sabdarrifa flowers) and the moisture content suggested that the dried flowers were better preserved. The study of the physico-chemical characteristics of Hibiscus sabdarrifa flowers has enabled us to highlight the importance of quality control and the need to prevent any adverse effects on consumer health.展开更多
Stainless steels have received wide attention as a substitute material for bipolar plates in high temperature proton exchange membrane fuel cell(HT-PEMFC).In the present work,the CrN,CrAlN and multilayer CrN/CrAlN coa...Stainless steels have received wide attention as a substitute material for bipolar plates in high temperature proton exchange membrane fuel cell(HT-PEMFC).In the present work,the CrN,CrAlN and multilayer CrN/CrAlN coatings were deposited on 316 L SS to increase the corrosion resistance and decrease the interfacial contact resistance.The deposited coatings exhibited face centered cubic phase structure and it was verified from the X-ray diffraction pattern.X-ray photo electron spectroscopy results showed the formation of both CrN and CrAlN layers on 316 L SS.CrN/CrAlN coating is more helpful in water management due to low surface roughness and high contact angle in the HT-PEMFC environment.The corrosion resistance behavior of all the samples were studied in 85%H_(3)PO_(4)solution at 140℃purged with H_(2)(HT-PEMFC anode)and O_(2)(HT-PEMFC cathode)gases.The results showed that all the coatings considerably improved the performance of 316 L SS and superior corrosion resistance was observed for CrN/CrAlN multilayer coating,whose protective efficiency was 98.12%and 96.14%in the two simulated HT-PEMFC environments.The results of electrochemical impedance spectroscopic studies demonstrated higher impedance for CrN/CrAlN coating.Surface morphological studies performed after corrosion studies revealed that protection ability of CrN/CrAlN coating still remained acceptable.A very low interfacial contact resistance value of 6 mΩ cm^(2) at 140 N/cm;was observed for CrN/CrAlN coating.Moreover,after corrosion studies,the interfacial contact resistance value of CrN/CrAlN coated 316 L was much lower than that of CrN and CrAlN coatings due to the increased oxidation resistance.The maximum power density of about 0.93 W/cm^(2) at 2 A/cm^(2) and output voltage of 0.96 V was observed for CrN/CrAlN coating.展开更多
AIM: Proteolytic degradation of the extracellular matrix facilitates cancer invasion and promotes metastasis. The study aims at evaluation of preoperative and postoperative serum cathepsins B and D levels in correlati...AIM: Proteolytic degradation of the extracellular matrix facilitates cancer invasion and promotes metastasis. The study aims at evaluation of preoperative and postoperative serum cathepsins B and D levels in correlation with selected anatomoclinical features of colorectal cancer.METHODS: Blood samples were collected from 63colorectal cancer patients before curative operation of the tumor 10 d later. Blood that was obtained from 20healthy volunteers, served as a control. The activity of cathepsin B was measured with Bz-DL-arginine-pNA as a substrate at pH 6.0, while cathepsin D activity was determined with urea-denatured hemoglobin (pH 4.0).RESULTS: The preoperative and postoperative activities of cathepsin B were significantly (P＜0.00001) lower in serum of colorectal cancer patients than in control group.However, postoperative values of this protease were significantly increased in comparison with preoperative ones (P = 0.031). Activity of cathepsin D appeared to be significantly higher in colorectal cancer sera (P＜0.00001)compared with controls. No statistically significant differences between preoperative and postoperative activity of cathepsin D were noted (P = 0.09). We revealed a strong linkage of cathepsins' levels with lymph node status and pT stage of colorectal cancer.CONCLUSION: Blood serum activities of cathepsin B and D depend on the time of sampling, tumor size and lymph node involvement. Significantly, increased activity of cathepsin D could indicate a malignant condition of the large intestine. In our work, the serum postoperative decrease of cathepsin B activity appears as an obvious concomitant of local lymph node metastasis-the wellknown clinicopathological feature of poor prognosis.展开更多
To determine the chemical composition of Galla chinensisextract （GCE） by several analysis techniques and to compare the efficacy of GCE and its main component（s） in inhibition of enamel demineralization, for the d...To determine the chemical composition of Galla chinensisextract （GCE） by several analysis techniques and to compare the efficacy of GCE and its main component（s） in inhibition of enamel demineralization, for the development of future anticaries agents, main organic composition of GCE was qualitatively determined by liquid chromatography-time of flight-mass spectrometry （LC-TOF-MS） and quantified by high-performance liquid chromatography-diode array detector （HPLC-DAD）. Inorganic ions were tested by inductively coupled plasma-atomic emission spectroscopy and F was especially measured by ion chromatography. Then, bovine enamel blocks were randomly divided into four treatment groups and were subjected to a pH-cycling regime for 12 times. Each cycle included 5-min applications with one of four treatments： 4g.L-1 GCE solution, 4g.L-1 gallic acid （GA） solution, I g.L-1 NaF solution （positive control）, deionized water （DDW, negative control）, and then 60-min application in pH 5.0 acidic buffer and 5-min application in neutral buffer. Acidic buffers were retained for calcium analysis. The main organic composition of GCE were GA and its isomer, and, to a lesser extent, small molecule gallotannins. The content of GA in GCE was 71.3%±0.2% （w/w）. Inorganic ions were present in various amounts, of which Ca was （136±2.82） μg.g-1, and Zn was （6.8±0.1） μg.g-1. No F was detected in GCE. in pH cycling, GA showed an effect similar to GCE in inhibiting enamel demineralization （P〉0.05）. GA was found to be the main effective, demineralization inhibiting component of GCE and could be a promising agent for the development of anticaries agents.展开更多
A carbon paste electrode (CPE) modified with ferrocene carboxylic acid (FcCA) and TiO2 nanoparticles was constructed by incorporating TiO2 nanoparticles and ferrocene carboxylic acid into the carbon paste matrix. The ...A carbon paste electrode (CPE) modified with ferrocene carboxylic acid (FcCA) and TiO2 nanoparticles was constructed by incorporating TiO2 nanoparticles and ferrocene carboxylic acid into the carbon paste matrix. The electrochemical behavior of captopril (CAP) at the surface of the modified electrode was investigated using electroanalytical methods. The modified electrode showed excellent electrocatalytic activity for the oxidation of CAP in aqueous solutions at physiological pH values. Cyclic voltammetric curves showed that the oxidation of CAP at the surface of the modified electrode reduced its overpotential by more than 290 mV. The modified electrode was used for detecting captopril using cyclic voltammetry and square wave voltammetry techniques. A calibration curve in the range of 0.03 to 2400 μmol/L was obtained that had a detection limit of 0.0096 μmol/L (3?) under the optimized conditions. The modified electrode was successfully used for the determination of captopril in pharmaceutical and biological samples.展开更多
Extract of oven dried leaves of Pongamia pinnata(L) Pierre was used for the synthesis of silver nanoparticles. Stable and crystalline silver nanoparticles were formed by the treatment of aqueous solution of AgNO_3(1m ...Extract of oven dried leaves of Pongamia pinnata(L) Pierre was used for the synthesis of silver nanoparticles. Stable and crystalline silver nanoparticles were formed by the treatment of aqueous solution of AgNO_3(1m M) with dried leaf extract of Pongamia pinnata(L) Pierre. UV-visible spectroscopy studies were carried out to quantify the formation of silver nanoparticles. Transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy were used to characterize the silver nanoparticles. TEM image divulges that silver nanoparticles are quite polydispersed, the size ranging from 20 nm to 50 nm with an average of 38 nm. Water soluble heterocyclic compounds such as flavones were mainly responsible for the reduction and stabilization of the nanoparticles. Silver nanoparticles were effective against Escherichia coli(ATCC 8739), Staphylococcus aureus(ATCC 6538p), Pseudomonas aeruginosa(ATCC 9027) and Klebsiella pneumoniae(clinical isolate). The move towards extracellular synthesis using dried biomass appears to be cost effective, eco-friendly to the conventional methods of nanoparticles synthesis.展开更多
This study explored the removal of five veterinary pharmaceuticals （VPs） （sulfamethoxazole （SMETOX）, trimethoprim （TMP）, ciprofloxacin （CIPRO）, dexamethasone （DEXA） and febantel （FEBA）） from different wa...This study explored the removal of five veterinary pharmaceuticals （VPs） （sulfamethoxazole （SMETOX）, trimethoprim （TMP）, ciprofloxacin （CIPRO）, dexamethasone （DEXA） and febantel （FEBA）） from different water matrices （Milli-Q water, model water, tap water and real pharmaceutical wastewater using four types of nanofiltration （NF） membranes （NF90, NF270, NF and HL） and two reverse osmosis （RO） membranes （LFC-1 and XLE）. All VPs were added to different water matrices at a concentration of 10 mg/L. Rejections of VPs and water flux were measured. The rejection increased with increase of molecular weight. The highest rejections were obtained with RO membranes （LFC-1, XLE） and tight NF （NF90） membrane. In general, the rejection of VPs was higher in model water and tap water than in Milli-Q water, but the water flux was lower. This was mainly explained by ion adsorption inside the membranes pores. Narrower pore size counteracted the effect of presence of low concentration of natural organic matter （NOM） in tap water. The NOM was assumed to enhance the adsorption of VPs onto membrane surface, increased the size exclusion and electrostatic repulsion also appeared during the transport. Investigated water matrices had influence on water flux decline due to their complexity.展开更多
With the size of the biopharmaceutical market exponentially increasing,there is an aligned growth in the importance of data-rich analyses,not only to assess drug product safety but also to assist drug development driv...With the size of the biopharmaceutical market exponentially increasing,there is an aligned growth in the importance of data-rich analyses,not only to assess drug product safety but also to assist drug development driven by the deeper understanding of structure/function relationships.In monoclonal antibodies,many functions are regulated by N-glycans present in the constant region of the heavy chains and their mechanisms of action are not completely known.The importance of their function focuses analytical research efforts on the development of robust,accurate and fast methods to support drug development and quality control.Released N-glycan analysis is considered as the gold standard for glycosylation characterisation;however,it is not the only method for quantitative analysis of glycoform heterogeneity.In this study,ten different analytical workflows for N-glycan analysis were compared using four monoclonal antibodies.While observing good comparability between the quantitative results generated,it was possible to appreciate the advantages and disadvantages of each technique and to summarise all the observations to guide the choice of the most appropriate analytical workflow according to application and the desired depth of data generated.展开更多
In this study, concentrations of Cr, Mn, Ni, Cu, Zn, Cd and Pb were determined in road dusts collected from different locations in Dhaka to assess source, contamination status and health risk. Energy-dispersive X-ray ...In this study, concentrations of Cr, Mn, Ni, Cu, Zn, Cd and Pb were determined in road dusts collected from different locations in Dhaka to assess source, contamination status and health risk. Energy-dispersive X-ray fluorescence spectroscopy and energy-dispersive X-ray spectroscopy were used to determine Cr, Mn, Ni, Cu, Zn, Cd and Pb and their mean concentrations were 162.27 ± 29.46, 721.18 ± 180.14, 35.65 ± 12.55, 104.56 ± 128.33, 515.32 ± 321.90,BDL, and 342.82 ± 591.20 mg/kg, respectively. Among the heavy metals, highest concentrations of Cu, Zn and Pb were found at urban sites-7(municipal waste dumping) and 8(medical waste incineration). Highest concentration of Cr followed by Cu and Zn was found at site-5(Tejgaon, urban). Principal component analysis revealed that anthropogenic activities are the potential sources for Cr, Ni, Cu, Zn and Pb while earth crust for Mn. Pollution index and pollution load index results suggested that all the sites were contaminated and/or degraded by Cr, Cu, Zn and Pb except sites-9(urban), 10(sub-urban), 11(rural) while sites-7 and 8(urban) were extremely degraded. For noncarcinogenic health risk, hazard quotient values for dermal were higher compared to that of inhalation/ingestion. Though hazard index values were less than 1 at all the sites, these were at least one order of magnitude higher for children group than that of adult group, thus the children group may face more noncarcinogenic health risk at sites -7 and 8. Values of incremental lifetime cancer risk were from 10to 10showed no carcinogenic health risk by road dusts contaminated with the heavy metals.展开更多
A liquid chromatography （HPLC） method with UV detection was developed for determination of sodium hyaluronate in pharmaceutical formulation. Sodium hyaluronate is a polymer of disaccharides, composed of D-glucuronic...A liquid chromatography （HPLC） method with UV detection was developed for determination of sodium hyaluronate in pharmaceutical formulation. Sodium hyaluronate is a polymer of disaccharides, composed of D-glucuronic acid and D-N-acetylglucosamine, linked via alternating 13-1, 4 and D-l, 3 glycosidic bonds. Being a polymer compound it lacks a UV absorbing chromophore. In the absence of a UV absorbing chromophore and highly polar nature of compound, the analysis becomes a major challenge. To overcome these problems a novel method for the determination of sodium hyaluronate was developed and validated based on size exclusion liquid chromatography （SEC） with UV detection. An isocratic mobile phase consisting of buffer 0.05 M potassium dihydrogen phosphate, pH adjusted to 7.0 using potassium hydroxide （10%） was used. Chromatography was carried out at 25 ~C on a BioSep SEC $2000, 300 mm ~ 7.8 mm column. The detection was carded out using variable wavelength UV-vis detector set at 205 nm. The compounds were eluted isocratically at a steady flow rate of 1.0 mL/min. Sodium hyaluronate retention time was about 4.9 min with an asymmetry factor of 1.93. A calibration curve was obtained from 1 to 38 g/mL （r〉0.9998）. Within-day % RSD was 1.0 and between-day % RSD was 1.10. Specificity/selectivity experiments revealed the absence of interference from excipients, recovery from spiked samples for sodium hyaluronate was 99-102. The developed method was applied to the determination of sodium hyaluronate in pharmaceutical drug substance and product.展开更多
Cuticular wax plays a major role in the growth and storage of plant fruits.The cuticular wax coating,which covers the outermost layer of a fruit’s epidermal cells,is insoluble in water.Cuticular wax is mainly compose...Cuticular wax plays a major role in the growth and storage of plant fruits.The cuticular wax coating,which covers the outermost layer of a fruit’s epidermal cells,is insoluble in water.Cuticular wax is mainly composed of very long-chain fatty acids(VLCFAs);their derivatives,including esters,primary alcohols,secondary alcohols,aldehydes,and ketones;and triterpenoids.This complex mixture of lipids is probably biosynthesized in the epidermal cells of most plants and exuded onto the surface.Cuticular wax not only makes the fruit less susceptible to microbial infection but also reduces mechanical damage to the fruit,thereby maintaining the fruit’s commodity value.To date,research has mostly focused on the changes,function,and regulation of fruit wax before harvest,while ignoring the changes and functions of wax in fruit storage.This paper reviews on the composition,structure,and metabolic regulation of cuticular wax in fruits.It also focuses on postharvest factors affecting wax composition,such as storage temperature,relative humidity(RH),gas atmosphere,and as exogenous hormones;and the effects of wax on fruit postharvest quality,including water dispersion,fruit softening,physiological disorders,and disease resistance.These summaries may be of assistance in better understanding the changes in cuticular wax in postharvest fruit and the resulting effects on fruit quality.展开更多
The thin and porous Fluoride Conversion Coating FCC with many cracks could not offer a significant improvement in corrosion resistance for Mg. Magnesium phosphate coating improves the corrosion resistance of Mg, good ...The thin and porous Fluoride Conversion Coating FCC with many cracks could not offer a significant improvement in corrosion resistance for Mg. Magnesium phosphate coating improves the corrosion resistance of Mg, good bioactivity, promotes cell viability and cyto-compatibility and exhibits antibacterial activity. However, rapid dissolution in Mg in acidic magnesium phosphate containing solutions leads to the development of an inhomogeneous coating. The present study attempts to prevent the excessive dissolution of Mg by forming a fluoride conversion coating as a pre-treatment in the first stage followed by deposition of magnesium phosphate coating in the second stage to develop magnesium fluoride-magnesium phosphate duplex coatings. The morphological features, structural characteristics, nature of functional groups, corrosion behavior in Hanks’ balanced salt solution and bioactivity in simulated body fluid are assessed to ascertain the suitability of the magnesium fluoride-magnesium phosphate duplex coating in controlling the rate of degradation of Mg and improving its bioactivity using uncoated Mg and fluoride conversion coated Mg as reference. The findings of the study reveal that the magnesium fluoride-magnesium phosphate duplex coating could offer an excellent corrosion resistance and improve the bioactivity of Mg.展开更多
A rapid,sensitive and simple spectrofluorimetric method was developed for the estimation of atorvastatin.In this method,the native fluorescence characteristics of atorvastatin have been studied in both acidic and basi...A rapid,sensitive and simple spectrofluorimetric method was developed for the estimation of atorvastatin.In this method,the native fluorescence characteristics of atorvastatin have been studied in both acidic and basic media.High sensitivity was obtained with 5% acetic acid at 389 nm using 276 nm for excitation.Regression analysis showed a good correlation coefficient(r=0.9995) between fluorescence intensity and concentration over the range of 1.5-4 mg/mL with detection limit of 0.012 mg/mL.The proposed method was successfully applied to the analysis of atorvastatin in pure and pharmaceutical dosage forms with average recovery of 100.2970.47%.The results were compared favorably with those of the reported method.展开更多
S-Nitrosothiols or thionitrites with the general formula RSNO are formally composed of the nitrosyl cation(NOt) and a thiolate(RSà), the base of the corresponding acids RSH. The smallest S-nitrosothiol is HSNO an...S-Nitrosothiols or thionitrites with the general formula RSNO are formally composed of the nitrosyl cation(NOt) and a thiolate(RSà), the base of the corresponding acids RSH. The smallest S-nitrosothiol is HSNO and derives from hydrogen sulfide(HSH, H_2S). The most common physiological S-nitrosothiols are derived from the amino acid L-cysteine(Cys SH). Thus, the simplest S-nitrosothiol is S-nitroso-L-cysteine(Cys SNO). Cys SNO is a spontaneous potent donor of nitric oxide(NO) which activates soluble guanylyl cyclase to form cyclic guanosine monophosphate(c GMP). This activation is associated with multiple biological actions that include relaxation of smooth muscle cells and inhibition of platelet aggregation.Like NO, Cys SNO is a short-lived species and occurs physiologically at concentrations around 1 n M in human blood. Cys SNO can be formed from Cys SH and higher oxides of NO including nitrous acid(HONO)and its anhydride(N_2O_3). The most characteristic feature of RSNO is the S-transnitrosation reaction by which the NOtgroup is reversibly transferred to another thiolate. By this way numerous RSNO can be formed such as the low-molecular-mass S-nitroso-N-acetyl-L-cysteine(SNAC) and S-nitroso-glutathione(GSNO), and the high-molecular-mass S-nitrosol-L-cysteine hemoglobin(Hb Cys SNO) present in erythrocytes and S-nitrosol-L-cysteine albumin(Alb Cys SNO) present in plasma at concentrations of the order of 200 n M. All above mentioned RSNO exert NO-related biological activity, but they must be administered intravenously. This important drawback can be overcome by lipophilic charge-free RSNO.Thus, we prepared the ethyl ester of SNAC, the S-nitroso-N-acetyl-L-cysteine ethyl ester(SNACET), from synthetic N-acetyl-L-cysteine ethyl ester(NACET). Both NACET and SNACET have improved pharmacological features over N-acetyl-L-cysteine(NAC) and S-nitroso-N-acetyl-L-cysteine(SNAC), respectively,including higher oral bioavailability. SNACET exerts NO-related activities which can be utilized in the urogenital tract and in the cardiovascular system. NACET, with high oral bioavailability, is a strong antioxidant and abundant precursor of GSH, unlike its free acid N-acetyl-L-cysteine(NAC). Here, we review the chemical and pharmacological properties of SNACET and NACET as well as their analytical chemistry.We also report new results from the ingestion of S-[^(15) N]nitroso-N-acetyl-L-cysteine ethyl ester(S^(15) NACET) demonstrating the favorable pharmacological profile of SNACET.展开更多
Here, Pd Ru nanoparticle networks（NPNs） with various compositions were synthesized through an inexpensive method in water as a green solvent, at different ratios of the H;PdCl;and RuCl;precursors. This is a fast, ro...Here, Pd Ru nanoparticle networks（NPNs） with various compositions were synthesized through an inexpensive method in water as a green solvent, at different ratios of the H;PdCl;and RuCl;precursors. This is a fast, room temperature and surfactant free strategy which is able to form high surface area metal nanosponges with a three-dimensional（3D） porous structure. The structure of as-prepared nanosponges was characterized using the techniques of field emission scanning electron microscopy（FESEM）, energy dispersive spectroscopy（EDS） and cyclic voltammetry（CV）. Then, the electrocatalytic activities of Pd Ru NPNs towards formic acid oxidation were examined by electrochemical measurements including CV,chronoamperometry, and electrochemical impedance spectroscopy（EIS）. Based on studies, it was found that the current density of formic acid oxidation（FAO） is strongly dependent on the composition of Pd Ru NPNs. The best performance was realized for Pd;Ru;NPNs compared to monometallic Pd counterpart and other bimetallic NPNs which might be ascribed to the role of Ru in the decrease of CO adsorption strength on the catalyst and consequently the priority of formic acid oxidation through the direct pathway. The Pd;Ru;NPNs also showed the maximum current density and stability in chronoamperometric measurements. In addition, comparative studies were performed between as-prepared NPNs and CNTs-supported Pd nanoparticles（Pd NPs/CNTs）. The present results demonstrated the unique structural advantages of NPNs compared to individual Pd NPs supported on the CNT which leads to the promising performance of NPNs as supportless catalysts for the oxidation of formic acid.展开更多
A new convenient colorimetric sensor for fructose based on anti-aggregation of citrate-capped gold nanoparticles（Au NPs） is presented. 4-Mercaptophenylboronic acid（MPBA） induces the aggregation of Au NPs, leading ...A new convenient colorimetric sensor for fructose based on anti-aggregation of citrate-capped gold nanoparticles（Au NPs） is presented. 4-Mercaptophenylboronic acid（MPBA） induces the aggregation of Au NPs, leading to a color change from red to blue. Fructose as a potent competitor has strong affinity for MPBA and a borate ester is formed between MPBA and fructose. There is an obvious color change from blue to red with increasing the concentration of fructose. The anti-aggregation effect of fructose on Au NPs was seen by the naked eye and monitored by UV–vis spectra. Our results showed that the absorbance ratio（A（519）/A（640）） was linear with fructose concentration in the range of 0.032–0.96 μmol/L（R^2= 0.996）, with a low detection limit of 0.01 μmol/L（S/N = 3）. Notably, a highly selective recognition of fructose was shown against other monosaccharide and disaccharide（glucose, mannose, galactose,lactose and saccharose）. With anti-aggregation assays higher selectivity is achievable. The results of this work provide a rapid method for evaluating the quantitative analysis of fructose in human plasma at physiologically meaningful concentrations and at neutral pH. The proposed procedure can be used as an efficient method for the precise and accurate determination of fructose.展开更多
The endocannabinoid system(ECS),particularly its signaling pathways and ligands,has garnered considerable interest in recent years.Along with clinical work investigating the ECS’functions,including its role in the de...The endocannabinoid system(ECS),particularly its signaling pathways and ligands,has garnered considerable interest in recent years.Along with clinical work investigating the ECS’functions,including its role in the development of neurological and inflammatory conditions,much research has focused on developing analytical protocols enabling the precise monitoring of the levels and metabolism of the most potent ECS ligands:exogenous phytocannabinoids(PCs)and endogenous cannabinoids(endocannabinoids,ECs).Solid-phase microextraction(SPME)is an advanced,non-exhaustive sample-preparation technique that facilitates the precise and efficient isolation of trace amounts of analytes,thus making it appealing for the analysis of PCs and ECs in complex matrices of plant and animal/human origin.In this paper,we review recent forensic medicine and toxicological studies wherein SPME has been applied to monitor levels of PCs and ECs in complex matrices,determine their effects on organism physiology,and assess their role in the development of several diseases.展开更多
基金Project FIS PI-17/00547(Instituto CarlosⅢ,Ministerio de Economía y Competitividad,Spain),which means that it was also partially supported by European Regional Development Funds(ERDF)the University of Granada(Spain)for the support。
文摘COVID-19,a disease caused by the novel coronavirus SARS-Co V-2,has produced a serious emergency for global public health,placing enormous stress on national health systems in many countries.Several studies suggest that cytokine storms(interleukins)may play an important role in severe cases of COVID-19.Neutralizing key inflammatory factors in cytokine release syndrome(CRS)could therefore be of great value in reducing the mortality rate.Tocilizumab(TCZ)in its intravenous(IV)form of administration-Ro Actemra?20 mg/m L(Roche)-is indicated for treatment of severe CRS patients.Preliminary investigations have concluded that inhibition of IL-6 with TCZ appears to be efficacious and safe,with several ongoing clinical trials.This has led to a huge increase in demand for IV TCZ for treating severe COVID-19 patients in hospitals,which has resulted in drug shortages.Here,we present a comparability study assessing the main critical physicochemical attributes of TCZ solutions used for infusion,at 6 mg/m L and 4 mg/m L,prepared from Ro Actemra?20 mg/m L(IV form)and from Ro Actemra?162 mg(0.9 m L solution pre-filled syringe,subcutaneous(SC)form),to evaluate the use of the latter for preparing clinical solutions required for IV administration,so that in a situation of shortage of the IV medicine,the SC form could be used to prepare the solutions for IV delivery of TCZ.It is important to remember that during the current pandemic all the medicines are used off-label,since none of them has yet been approved for the treatment of COVID-19.
基金Project supported by Jilin Province Science and Technology Development Plan Project(20210201061GX)。
文摘Baicalin,a major flavonoid compound found in Scutellariae radix,is the first SARS-CoV-23CLpro virus inhibitor.Therefore,developing an accurate and reliable strategy to detect baicalin in biological systems is vital.Herein,we report the first indolyl-lanthanide metal-organic framework(MOF)materials and their application as baicalin sensors.The results of this study indicate that the new crystal structure has good stability and luminous performance.The detection limits of baicalin in serum and urine are 0.05 and 0.04μmol/L,respectively,suggesting high sensitivity and selectivity.Various background substances present in practical samples,such as anions,cations,and amino acids,do not interfere with the photoluminescence analytical signal of Eu^(3+).We identified that the quenching of the Eu-MOF is due to the inner filter effect,absorption energy competition,and photoinduced electron transfer among the baicalin,ligand,and MOF through powder X-ray diffraction analysis,Fourier transform infrared spectroscopy,luminescence lifetimes,ultraviolet studies,and computational analysis.Thus,we designed a convenient,sensitive,and facile detection method using the Eu-MOF and demonstrate that Eu^(3+)-based materials are promising sensors for baicalin detection in actual serum and urine.Additionally,the prepared Eu-MOF@polyvinyl alcohol composite matrix membrane test film has considerable practical application value for the portable detection of baicalin.
基金supported by the Slovak grant agency VEGA(project no 1/0003/21)analyses of foreign co-authors also by internal sources(grant no.SGS_2025_001)of their workplaces.
文摘Dill(Anethum graveolens),an annual species,was used to study the impact of metallic pollution potentially spreading fromthe nickel smelter dump in Dolna Streda(Slovakia)by monitoring 55 elements.Despite the proximity of this dump(1 km),only soil Ni(54.8 mg/kg)or Pb(47.3 mg/kg),but not Cr,Mn,Fe or Co(main elements of the dump’s sludge)was elevated in given garden soil compared to two control sites.Mainly flowers and/or leaves contained significantly higher amounts of Ni,Cr,Pb,Cu,As,Sb,Sn,V,W,and some rare earth elements at the site close to the dump.Correlation between elements in organs and soil was significant mainly in stem or root but the bioaccumulation factor was typically low(<0.02)for most elements.A positive finding was that the 2022/2024 comparison revealed a decline in most elements in dill leaves,even at the dump site,which may reflect a decrease in the content of air PM particles.Soluble phenols were less accumulated in plants close to the nickel smelter dump,but flavonols showed the opposite trend,and free amino acids were positively correlated with many elements in the stem and root.An evaluation of commercial dill samples revealed variability(e.g.,up to 0.7 mg Cd/kg dry weight)but subsequent NCA and PCA analyses clearly separated the dump locality from other samples.However,significant differences in the content of Cd,Ni,Pb,As,and other elements encourage precise control of commercially available dill dry matter.
文摘Hibiscus sabdarrifa flowers are known the world over. In Cote d’Ivoire, they are commonly known as “bissap” and are of great interest to local people, who use them to make an eponymous herbal tea. This drink has potential medicinal and nutritional value (Khan et al., 2022). Nine (9) samples of dried flowers of the plant, packaged in 3 g sachets of a local Kuinafo brand, were used for physico-chemical analyses. Heavy metals, mineral salts, ash and moisture content were determined using methods adapted from the Association of Official Analytical Chemists (AOAC). The results showed the presence of heavy metals at levels whose intake should take into account the weight of the consumer in the case of mercury and arsenic (0.5 mg/Kg and 0.7 mg/Kg respectively). Apart from lead, whose level was not compliant (1.310 mg/Kg for a CSHPF standard of 0.5 mg/Kg), cadmium had a regulatory level (0.18 mg/Kg for a CSHPF standard of 0.20 mg/Kg). Nutrient intakes were significant (calcium, iron and potassium respectively at 1.79 g/100g;17.27 mg/100g and 1.76 g/100g of dried Hibiscus sabdarrifa flowers) and the moisture content suggested that the dried flowers were better preserved. The study of the physico-chemical characteristics of Hibiscus sabdarrifa flowers has enabled us to highlight the importance of quality control and the need to prevent any adverse effects on consumer health.
基金the financial assistance received from Science and Engineering Research Board(SERB PDF/2017/002594),New Delhi,India。
文摘Stainless steels have received wide attention as a substitute material for bipolar plates in high temperature proton exchange membrane fuel cell(HT-PEMFC).In the present work,the CrN,CrAlN and multilayer CrN/CrAlN coatings were deposited on 316 L SS to increase the corrosion resistance and decrease the interfacial contact resistance.The deposited coatings exhibited face centered cubic phase structure and it was verified from the X-ray diffraction pattern.X-ray photo electron spectroscopy results showed the formation of both CrN and CrAlN layers on 316 L SS.CrN/CrAlN coating is more helpful in water management due to low surface roughness and high contact angle in the HT-PEMFC environment.The corrosion resistance behavior of all the samples were studied in 85%H_(3)PO_(4)solution at 140℃purged with H_(2)(HT-PEMFC anode)and O_(2)(HT-PEMFC cathode)gases.The results showed that all the coatings considerably improved the performance of 316 L SS and superior corrosion resistance was observed for CrN/CrAlN multilayer coating,whose protective efficiency was 98.12%and 96.14%in the two simulated HT-PEMFC environments.The results of electrochemical impedance spectroscopic studies demonstrated higher impedance for CrN/CrAlN coating.Surface morphological studies performed after corrosion studies revealed that protection ability of CrN/CrAlN coating still remained acceptable.A very low interfacial contact resistance value of 6 mΩ cm^(2) at 140 N/cm;was observed for CrN/CrAlN coating.Moreover,after corrosion studies,the interfacial contact resistance value of CrN/CrAlN coated 316 L was much lower than that of CrN and CrAlN coatings due to the increased oxidation resistance.The maximum power density of about 0.93 W/cm^(2) at 2 A/cm^(2) and output voltage of 0.96 V was observed for CrN/CrAlN coating.
基金Supported by the Polish State Committee for Scientific Research, No. 3 PO5B 07922
文摘AIM: Proteolytic degradation of the extracellular matrix facilitates cancer invasion and promotes metastasis. The study aims at evaluation of preoperative and postoperative serum cathepsins B and D levels in correlation with selected anatomoclinical features of colorectal cancer.METHODS: Blood samples were collected from 63colorectal cancer patients before curative operation of the tumor 10 d later. Blood that was obtained from 20healthy volunteers, served as a control. The activity of cathepsin B was measured with Bz-DL-arginine-pNA as a substrate at pH 6.0, while cathepsin D activity was determined with urea-denatured hemoglobin (pH 4.0).RESULTS: The preoperative and postoperative activities of cathepsin B were significantly (P＜0.00001) lower in serum of colorectal cancer patients than in control group.However, postoperative values of this protease were significantly increased in comparison with preoperative ones (P = 0.031). Activity of cathepsin D appeared to be significantly higher in colorectal cancer sera (P＜0.00001)compared with controls. No statistically significant differences between preoperative and postoperative activity of cathepsin D were noted (P = 0.09). We revealed a strong linkage of cathepsins' levels with lymph node status and pT stage of colorectal cancer.CONCLUSION: Blood serum activities of cathepsin B and D depend on the time of sampling, tumor size and lymph node involvement. Significantly, increased activity of cathepsin D could indicate a malignant condition of the large intestine. In our work, the serum postoperative decrease of cathepsin B activity appears as an obvious concomitant of local lymph node metastasis-the wellknown clinicopathological feature of poor prognosis.
基金supported by the National Natural Science Foundation of China (grant nos. 30572409 and 30430800)Youth Foundation of Sichuan Province in China (grant no. 07ZQ026-020)
文摘To determine the chemical composition of Galla chinensisextract （GCE） by several analysis techniques and to compare the efficacy of GCE and its main component（s） in inhibition of enamel demineralization, for the development of future anticaries agents, main organic composition of GCE was qualitatively determined by liquid chromatography-time of flight-mass spectrometry （LC-TOF-MS） and quantified by high-performance liquid chromatography-diode array detector （HPLC-DAD）. Inorganic ions were tested by inductively coupled plasma-atomic emission spectroscopy and F was especially measured by ion chromatography. Then, bovine enamel blocks were randomly divided into four treatment groups and were subjected to a pH-cycling regime for 12 times. Each cycle included 5-min applications with one of four treatments： 4g.L-1 GCE solution, 4g.L-1 gallic acid （GA） solution, I g.L-1 NaF solution （positive control）, deionized water （DDW, negative control）, and then 60-min application in pH 5.0 acidic buffer and 5-min application in neutral buffer. Acidic buffers were retained for calcium analysis. The main organic composition of GCE were GA and its isomer, and, to a lesser extent, small molecule gallotannins. The content of GA in GCE was 71.3%±0.2% （w/w）. Inorganic ions were present in various amounts, of which Ca was （136±2.82） μg.g-1, and Zn was （6.8±0.1） μg.g-1. No F was detected in GCE. in pH cycling, GA showed an effect similar to GCE in inhibiting enamel demineralization （P〉0.05）. GA was found to be the main effective, demineralization inhibiting component of GCE and could be a promising agent for the development of anticaries agents.
文摘A carbon paste electrode (CPE) modified with ferrocene carboxylic acid (FcCA) and TiO2 nanoparticles was constructed by incorporating TiO2 nanoparticles and ferrocene carboxylic acid into the carbon paste matrix. The electrochemical behavior of captopril (CAP) at the surface of the modified electrode was investigated using electroanalytical methods. The modified electrode showed excellent electrocatalytic activity for the oxidation of CAP in aqueous solutions at physiological pH values. Cyclic voltammetric curves showed that the oxidation of CAP at the surface of the modified electrode reduced its overpotential by more than 290 mV. The modified electrode was used for detecting captopril using cyclic voltammetry and square wave voltammetry techniques. A calibration curve in the range of 0.03 to 2400 μmol/L was obtained that had a detection limit of 0.0096 μmol/L (3?) under the optimized conditions. The modified electrode was successfully used for the determination of captopril in pharmaceutical and biological samples.
文摘Extract of oven dried leaves of Pongamia pinnata(L) Pierre was used for the synthesis of silver nanoparticles. Stable and crystalline silver nanoparticles were formed by the treatment of aqueous solution of AgNO_3(1m M) with dried leaf extract of Pongamia pinnata(L) Pierre. UV-visible spectroscopy studies were carried out to quantify the formation of silver nanoparticles. Transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy were used to characterize the silver nanoparticles. TEM image divulges that silver nanoparticles are quite polydispersed, the size ranging from 20 nm to 50 nm with an average of 38 nm. Water soluble heterocyclic compounds such as flavones were mainly responsible for the reduction and stabilization of the nanoparticles. Silver nanoparticles were effective against Escherichia coli(ATCC 8739), Staphylococcus aureus(ATCC 6538p), Pseudomonas aeruginosa(ATCC 9027) and Klebsiella pneumoniae(clinical isolate). The move towards extracellular synthesis using dried biomass appears to be cost effective, eco-friendly to the conventional methods of nanoparticles synthesis.
基金supported by the Croatian Ministry of Science, Education and Sports Projects: 125-1253008-3009 membrane and adsorption processes for removal of organic compounds in water treatment, 125-1253008-1350 advanced analytical methods for pharmaceuticals determination in the environmentUKF project 05/08: Reduction of environmental risks posed by pharmaceuticals and their degradation products in process wastewaters, through RO/NF membrane treatment (REPHAD)
文摘This study explored the removal of five veterinary pharmaceuticals （VPs） （sulfamethoxazole （SMETOX）, trimethoprim （TMP）, ciprofloxacin （CIPRO）, dexamethasone （DEXA） and febantel （FEBA）） from different water matrices （Milli-Q water, model water, tap water and real pharmaceutical wastewater using four types of nanofiltration （NF） membranes （NF90, NF270, NF and HL） and two reverse osmosis （RO） membranes （LFC-1 and XLE）. All VPs were added to different water matrices at a concentration of 10 mg/L. Rejections of VPs and water flux were measured. The rejection increased with increase of molecular weight. The highest rejections were obtained with RO membranes （LFC-1, XLE） and tight NF （NF90） membrane. In general, the rejection of VPs was higher in model water and tap water than in Milli-Q water, but the water flux was lower. This was mainly explained by ion adsorption inside the membranes pores. Narrower pore size counteracted the effect of presence of low concentration of natural organic matter （NOM） in tap water. The NOM was assumed to enhance the adsorption of VPs onto membrane surface, increased the size exclusion and electrostatic repulsion also appeared during the transport. Investigated water matrices had influence on water flux decline due to their complexity.
文摘With the size of the biopharmaceutical market exponentially increasing,there is an aligned growth in the importance of data-rich analyses,not only to assess drug product safety but also to assist drug development driven by the deeper understanding of structure/function relationships.In monoclonal antibodies,many functions are regulated by N-glycans present in the constant region of the heavy chains and their mechanisms of action are not completely known.The importance of their function focuses analytical research efforts on the development of robust,accurate and fast methods to support drug development and quality control.Released N-glycan analysis is considered as the gold standard for glycosylation characterisation;however,it is not the only method for quantitative analysis of glycoform heterogeneity.In this study,ten different analytical workflows for N-glycan analysis were compared using four monoclonal antibodies.While observing good comparability between the quantitative results generated,it was possible to appreciate the advantages and disadvantages of each technique and to summarise all the observations to guide the choice of the most appropriate analytical workflow according to application and the desired depth of data generated.
基金the financial support by the National Natural Science Foundation of China (42042050, U2005207)Natural Science Foundation of Fujian Province, China (2020J0141)。
文摘In this study, concentrations of Cr, Mn, Ni, Cu, Zn, Cd and Pb were determined in road dusts collected from different locations in Dhaka to assess source, contamination status and health risk. Energy-dispersive X-ray fluorescence spectroscopy and energy-dispersive X-ray spectroscopy were used to determine Cr, Mn, Ni, Cu, Zn, Cd and Pb and their mean concentrations were 162.27 ± 29.46, 721.18 ± 180.14, 35.65 ± 12.55, 104.56 ± 128.33, 515.32 ± 321.90,BDL, and 342.82 ± 591.20 mg/kg, respectively. Among the heavy metals, highest concentrations of Cu, Zn and Pb were found at urban sites-7(municipal waste dumping) and 8(medical waste incineration). Highest concentration of Cr followed by Cu and Zn was found at site-5(Tejgaon, urban). Principal component analysis revealed that anthropogenic activities are the potential sources for Cr, Ni, Cu, Zn and Pb while earth crust for Mn. Pollution index and pollution load index results suggested that all the sites were contaminated and/or degraded by Cr, Cu, Zn and Pb except sites-9(urban), 10(sub-urban), 11(rural) while sites-7 and 8(urban) were extremely degraded. For noncarcinogenic health risk, hazard quotient values for dermal were higher compared to that of inhalation/ingestion. Though hazard index values were less than 1 at all the sites, these were at least one order of magnitude higher for children group than that of adult group, thus the children group may face more noncarcinogenic health risk at sites -7 and 8. Values of incremental lifetime cancer risk were from 10to 10showed no carcinogenic health risk by road dusts contaminated with the heavy metals.
文摘A liquid chromatography （HPLC） method with UV detection was developed for determination of sodium hyaluronate in pharmaceutical formulation. Sodium hyaluronate is a polymer of disaccharides, composed of D-glucuronic acid and D-N-acetylglucosamine, linked via alternating 13-1, 4 and D-l, 3 glycosidic bonds. Being a polymer compound it lacks a UV absorbing chromophore. In the absence of a UV absorbing chromophore and highly polar nature of compound, the analysis becomes a major challenge. To overcome these problems a novel method for the determination of sodium hyaluronate was developed and validated based on size exclusion liquid chromatography （SEC） with UV detection. An isocratic mobile phase consisting of buffer 0.05 M potassium dihydrogen phosphate, pH adjusted to 7.0 using potassium hydroxide （10%） was used. Chromatography was carried out at 25 ~C on a BioSep SEC $2000, 300 mm ~ 7.8 mm column. The detection was carded out using variable wavelength UV-vis detector set at 205 nm. The compounds were eluted isocratically at a steady flow rate of 1.0 mL/min. Sodium hyaluronate retention time was about 4.9 min with an asymmetry factor of 1.93. A calibration curve was obtained from 1 to 38 g/mL （r〉0.9998）. Within-day % RSD was 1.0 and between-day % RSD was 1.10. Specificity/selectivity experiments revealed the absence of interference from excipients, recovery from spiked samples for sodium hyaluronate was 99-102. The developed method was applied to the determination of sodium hyaluronate in pharmaceutical drug substance and product.
基金This work was supported by the National Natural Science Foundation of China(31772042)Ramóny Cajal grant(RYC2020-030365-I)+1 种基金Xunta de Galicia for supporting the program(Excelencia-ED431F2022/01)the Key Research&Development Program of Zhejiang Province(2021C02015).
文摘Cuticular wax plays a major role in the growth and storage of plant fruits.The cuticular wax coating,which covers the outermost layer of a fruit’s epidermal cells,is insoluble in water.Cuticular wax is mainly composed of very long-chain fatty acids(VLCFAs);their derivatives,including esters,primary alcohols,secondary alcohols,aldehydes,and ketones;and triterpenoids.This complex mixture of lipids is probably biosynthesized in the epidermal cells of most plants and exuded onto the surface.Cuticular wax not only makes the fruit less susceptible to microbial infection but also reduces mechanical damage to the fruit,thereby maintaining the fruit’s commodity value.To date,research has mostly focused on the changes,function,and regulation of fruit wax before harvest,while ignoring the changes and functions of wax in fruit storage.This paper reviews on the composition,structure,and metabolic regulation of cuticular wax in fruits.It also focuses on postharvest factors affecting wax composition,such as storage temperature,relative humidity(RH),gas atmosphere,and as exogenous hormones;and the effects of wax on fruit postharvest quality,including water dispersion,fruit softening,physiological disorders,and disease resistance.These summaries may be of assistance in better understanding the changes in cuticular wax in postharvest fruit and the resulting effects on fruit quality.
基金University Grand Commission(UGC)for providing a research fellowship to support this research program under the non-net category。
文摘The thin and porous Fluoride Conversion Coating FCC with many cracks could not offer a significant improvement in corrosion resistance for Mg. Magnesium phosphate coating improves the corrosion resistance of Mg, good bioactivity, promotes cell viability and cyto-compatibility and exhibits antibacterial activity. However, rapid dissolution in Mg in acidic magnesium phosphate containing solutions leads to the development of an inhomogeneous coating. The present study attempts to prevent the excessive dissolution of Mg by forming a fluoride conversion coating as a pre-treatment in the first stage followed by deposition of magnesium phosphate coating in the second stage to develop magnesium fluoride-magnesium phosphate duplex coatings. The morphological features, structural characteristics, nature of functional groups, corrosion behavior in Hanks’ balanced salt solution and bioactivity in simulated body fluid are assessed to ascertain the suitability of the magnesium fluoride-magnesium phosphate duplex coating in controlling the rate of degradation of Mg and improving its bioactivity using uncoated Mg and fluoride conversion coated Mg as reference. The findings of the study reveal that the magnesium fluoride-magnesium phosphate duplex coating could offer an excellent corrosion resistance and improve the bioactivity of Mg.
文摘A rapid,sensitive and simple spectrofluorimetric method was developed for the estimation of atorvastatin.In this method,the native fluorescence characteristics of atorvastatin have been studied in both acidic and basic media.High sensitivity was obtained with 5% acetic acid at 389 nm using 276 nm for excitation.Regression analysis showed a good correlation coefficient(r=0.9995) between fluorescence intensity and concentration over the range of 1.5-4 mg/mL with detection limit of 0.012 mg/mL.The proposed method was successfully applied to the analysis of atorvastatin in pure and pharmaceutical dosage forms with average recovery of 100.2970.47%.The results were compared favorably with those of the reported method.
文摘S-Nitrosothiols or thionitrites with the general formula RSNO are formally composed of the nitrosyl cation(NOt) and a thiolate(RSà), the base of the corresponding acids RSH. The smallest S-nitrosothiol is HSNO and derives from hydrogen sulfide(HSH, H_2S). The most common physiological S-nitrosothiols are derived from the amino acid L-cysteine(Cys SH). Thus, the simplest S-nitrosothiol is S-nitroso-L-cysteine(Cys SNO). Cys SNO is a spontaneous potent donor of nitric oxide(NO) which activates soluble guanylyl cyclase to form cyclic guanosine monophosphate(c GMP). This activation is associated with multiple biological actions that include relaxation of smooth muscle cells and inhibition of platelet aggregation.Like NO, Cys SNO is a short-lived species and occurs physiologically at concentrations around 1 n M in human blood. Cys SNO can be formed from Cys SH and higher oxides of NO including nitrous acid(HONO)and its anhydride(N_2O_3). The most characteristic feature of RSNO is the S-transnitrosation reaction by which the NOtgroup is reversibly transferred to another thiolate. By this way numerous RSNO can be formed such as the low-molecular-mass S-nitroso-N-acetyl-L-cysteine(SNAC) and S-nitroso-glutathione(GSNO), and the high-molecular-mass S-nitrosol-L-cysteine hemoglobin(Hb Cys SNO) present in erythrocytes and S-nitrosol-L-cysteine albumin(Alb Cys SNO) present in plasma at concentrations of the order of 200 n M. All above mentioned RSNO exert NO-related biological activity, but they must be administered intravenously. This important drawback can be overcome by lipophilic charge-free RSNO.Thus, we prepared the ethyl ester of SNAC, the S-nitroso-N-acetyl-L-cysteine ethyl ester(SNACET), from synthetic N-acetyl-L-cysteine ethyl ester(NACET). Both NACET and SNACET have improved pharmacological features over N-acetyl-L-cysteine(NAC) and S-nitroso-N-acetyl-L-cysteine(SNAC), respectively,including higher oral bioavailability. SNACET exerts NO-related activities which can be utilized in the urogenital tract and in the cardiovascular system. NACET, with high oral bioavailability, is a strong antioxidant and abundant precursor of GSH, unlike its free acid N-acetyl-L-cysteine(NAC). Here, we review the chemical and pharmacological properties of SNACET and NACET as well as their analytical chemistry.We also report new results from the ingestion of S-[^(15) N]nitroso-N-acetyl-L-cysteine ethyl ester(S^(15) NACET) demonstrating the favorable pharmacological profile of SNACET.
文摘Here, Pd Ru nanoparticle networks（NPNs） with various compositions were synthesized through an inexpensive method in water as a green solvent, at different ratios of the H;PdCl;and RuCl;precursors. This is a fast, room temperature and surfactant free strategy which is able to form high surface area metal nanosponges with a three-dimensional（3D） porous structure. The structure of as-prepared nanosponges was characterized using the techniques of field emission scanning electron microscopy（FESEM）, energy dispersive spectroscopy（EDS） and cyclic voltammetry（CV）. Then, the electrocatalytic activities of Pd Ru NPNs towards formic acid oxidation were examined by electrochemical measurements including CV,chronoamperometry, and electrochemical impedance spectroscopy（EIS）. Based on studies, it was found that the current density of formic acid oxidation（FAO） is strongly dependent on the composition of Pd Ru NPNs. The best performance was realized for Pd;Ru;NPNs compared to monometallic Pd counterpart and other bimetallic NPNs which might be ascribed to the role of Ru in the decrease of CO adsorption strength on the catalyst and consequently the priority of formic acid oxidation through the direct pathway. The Pd;Ru;NPNs also showed the maximum current density and stability in chronoamperometric measurements. In addition, comparative studies were performed between as-prepared NPNs and CNTs-supported Pd nanoparticles（Pd NPs/CNTs）. The present results demonstrated the unique structural advantages of NPNs compared to individual Pd NPs supported on the CNT which leads to the promising performance of NPNs as supportless catalysts for the oxidation of formic acid.
文摘A new convenient colorimetric sensor for fructose based on anti-aggregation of citrate-capped gold nanoparticles（Au NPs） is presented. 4-Mercaptophenylboronic acid（MPBA） induces the aggregation of Au NPs, leading to a color change from red to blue. Fructose as a potent competitor has strong affinity for MPBA and a borate ester is formed between MPBA and fructose. There is an obvious color change from blue to red with increasing the concentration of fructose. The anti-aggregation effect of fructose on Au NPs was seen by the naked eye and monitored by UV–vis spectra. Our results showed that the absorbance ratio（A（519）/A（640）） was linear with fructose concentration in the range of 0.032–0.96 μmol/L（R^2= 0.996）, with a low detection limit of 0.01 μmol/L（S/N = 3）. Notably, a highly selective recognition of fructose was shown against other monosaccharide and disaccharide（glucose, mannose, galactose,lactose and saccharose）. With anti-aggregation assays higher selectivity is achievable. The results of this work provide a rapid method for evaluating the quantitative analysis of fructose in human plasma at physiologically meaningful concentrations and at neutral pH. The proposed procedure can be used as an efficient method for the precise and accurate determination of fructose.
文摘The endocannabinoid system(ECS),particularly its signaling pathways and ligands,has garnered considerable interest in recent years.Along with clinical work investigating the ECS’functions,including its role in the development of neurological and inflammatory conditions,much research has focused on developing analytical protocols enabling the precise monitoring of the levels and metabolism of the most potent ECS ligands:exogenous phytocannabinoids(PCs)and endogenous cannabinoids(endocannabinoids,ECs).Solid-phase microextraction(SPME)is an advanced,non-exhaustive sample-preparation technique that facilitates the precise and efficient isolation of trace amounts of analytes,thus making it appealing for the analysis of PCs and ECs in complex matrices of plant and animal/human origin.In this paper,we review recent forensic medicine and toxicological studies wherein SPME has been applied to monitor levels of PCs and ECs in complex matrices,determine their effects on organism physiology,and assess their role in the development of several diseases.
