Glucose electro-oxidation on Pt(100) in phosphate buffer solution (pH 7): A mechanistic study

2020 ◽  
Vol 354 ◽  
pp. 136765 ◽  
Author(s):  
Gisele A.B. Mello ◽  
William Cheuquepán ◽  
Valentín Briega-Martos ◽  
Juan M. Feliu
2015 ◽  
Vol 7 (20) ◽  
pp. 8673-8682 ◽  
Author(s):  
Nagaraj P. Shetti ◽  
Shweta J. Malode ◽  
Sharanappa T. Nandibewoor

Gold electrode was used for the oxidation of captopril in phosphate buffer solution pH 3.6 to study the influence of several physico-chemical parameters like potential, scan rate, pH and concentration by cyclic, linear sweep and differential pulse voltammetry.


e-Polymers ◽  
2013 ◽  
Vol 13 (1) ◽  
Author(s):  
Aidi Zhang ◽  
Derun Ding ◽  
Jicun Ren ◽  
Xiangli Zhu ◽  
Youhong Yao

Abstract A novel route is demonstrated for the synthesis of 2-N-carboxymethyl-6- O-diethylaminoethyl-chitosan (DEAE-CMC) by incorporation of carboxymethyl groups as hydrophilic moieties to the C2-NH2, and diethylaminoethyl groups as hydrophobic moieties to the C6-CH2OH of the structural unit of chitosan, via a protection-graft-deprotection procedure with benzaldehyde as protective agent. The structure, morphology, and thermal properties of the chitosan graft copolymers were characterized by means of FT-IR, 1H NMR, SEM, TGA and DSC. Chitosan and its derivatives were used as carrier of model drug-Vitamin B12 (VB12), and their controlled delivery behaviour in phosphate buffer solution (pH 7.4) were studied. The results show that the release rate of VB12 from the carrier of DEAE-CMC copolymer becomes much slower than that of chitosan in phosphate buffer solution.


Author(s):  
Luma Safa el-din Al-Hassnaui

Danazol is a synthetic steroid used for endometriosis treatment, haslow bioavailability as it is practically insoluble in water. This study has been carried out to prepare and characterize danazol nanoparticles by nanoprecipitation method at a different polymer to drug ratios of 0.5:1,1:1,2:1 and 3:1 using different polymers of CMC-30 and various grades of HPMC and PVP,as stabilizers. Variables that might affect the particle size as polymer type,polymer to drug ratio,temperature of precipitation,addition rate of danazol solution,volume ratio,time of stirring,concentrationof drug,have been investigated. The particle size of the prepared formulas has been in the nano-sized except those using CMC and the best formula has beenF20 at a polymer to drug ratio of0.5:1 which has given the smallest particle sizeof 33nm.The investigations of the drug–stabilizer compatibility havebeen studied by FTIR and DSC,crystalline state by XRD,size,and shape of nanoparticles by FESEM and the results showed that there has been no interaction between the danazol and stabilizer and there has been a partial conversion of danazol from crystalline to an amorphous state with a size below 100nm. Most of the studied factors havebeen found affect the particle size of the nanoparticles.The Entrapment efficiency has been (91.3% ± 0.4) in the (F20). The solubility study revealed that 6.75,4.97 and 5.1 folds increased of solubility of danazol for nanoparticles than that for raw in distilled water,0.1N HCl and in phosphate buffer of pH 6.8.The simple capsule has been prepared by incorporation of freeze-dried of F20 with lactose as a filler and the in vitro dissolution study has been conducted using 0.1N HCl (pH 1.2) with 2% w/v Brij-35,phosphate buffer solution(pH 6.8) with 2% w/v Brij-35as dissolution media. Within 30 minutes,100% of the danazol has been released from the nanoparticle capsule in both dissolution media compared to the raw and physical blend capsules as controls havebeen nearly complete in 120 minutes.One can conclude that Antisolvent method is an easy,efficient method to prepare danazol nanoparticles with an intense effect on solubility and faster in vitro dissolution rate than raw drug and its physical blend with stabilizer.


2019 ◽  
Vol 9 (4-A) ◽  
pp. 1-8
Author(s):  
Gouranga Nandi

Investigation of the effects of viscoelasticity and hydration kinetic on the drug release behavior from the poly (sodium acrylate)-grafted-gellan matrix (PSAc-g-GG) was the main objective of this study. At first, poly (acrylic acid)-grafted-gellan was treated with 0.05M NaOH to obtain poly (sodium acrylate)-grafted-gellan followed by its purification and subsequent lyophilicity study and viscoelastic study on PSAc-g-GG with different degree of grafting. The study revealed that the degree of grafting greatly affects the viscoelastic and rheologic characteristics of the copolymer, which further affect the drug release profile from the polymeric matrix. The  copolymer with highest grafting (626.3%) exhibited much higher starting % strain (17.79%), stress (53.7 Pa) for structural breakdown at Gꞌ = Gꞌꞌ (214.4 Pa), higher storage modulus (G’), much greater values of complex viscosity (11.5 Pa.s) and cross-over point (Gꞌ = Gꞌꞌ =271.65 Pa) compared to that of the batch of copolymer with lower grafting. The water uptake index (%WE) was found to be directly proportional to the percentage grafting (%G), whereas the batches with higher grafting  revealed lower initial swelling rate representing its inversely proportional relation to %grafting in case of 0.1N HCl acid. Equilibrium swelling and hydration were also found to be proportional to % grafting.  The similar effect was observed in phosphate buffer solution (pH 6.8) with an exception that the degree of the swelling parameters obtained from phosphate buffer was very much greater compared to that found in 0.1N HCl. PSAc-g-GG exhibited extended drug release over a period of 10 hours with the drug release mechanism based on Case-1 Fickian diffusion or square root of time kinetic. The study also exhibited the usefulness of viscoelastic and swelling study in order to identify the effects of the degree of grafting on the drug release.


2010 ◽  
Vol 7 (1) ◽  
pp. 320-324 ◽  
Author(s):  
L. Latheeshjlal ◽  
P. Parthiban ◽  
V. Alagarsamy ◽  
M. Sunil ◽  
J. Vaidhya Mahul ◽  
...  

Simple, rapid and accurate, spectrophotometric method for the determination of losartan potassium by using bromothymol blue as a chromogen and phosphate buffer solution (pH 3-4) as a diluting agent was developed. The developed colour shows maximum absorbance at 620 nm and it was observed that the absorbance of different dilution from the plots the calibration curve between the concentrations in x-axis, absorbance at y-axis. The recovery studies were also carried out to ensure the reproducibility and repeatability. This recovery studies shows between 96.82-100.08% for the different formulation. Hence, it was concluded that the developed simple, precise and accurate method can be effectively used for the routine analysis of losartan potassium


2021 ◽  
pp. 1608-1614
Author(s):  
Nadezhda Sachivkina ◽  
Irina Podoprigora ◽  
Dmitry Bokov

Background and Aim: Different Candida species isolated in humans and animals have different types of parasite activity. The most pathogenic species is Candida albicans followed by Candida tropicalis. However, the effects of the morphology of Candida krusei, Candida guilliermondii, and Candida glabrata biofilms on the pathogenicity of these species have not been fully characterized. To the best of our knowledge, there is no literature on the effect of farnesol on rare Candida species. This study aimed to check the effect of different farnesol concentrations on the species C. krusei, C. guilliermondii, and C. glabrata compared with the strain C. albicans ATCC 10231, which has been widely studied, and is a strong producer of biofilms. Materials and Methods: We studied the morphological and densitometric parameters of biofilms produced by Candida species under the influence of the drug farnesol (Sigma-Aldrich, St. Louis, MO). We used a heart brain broth with the addition of 2% bovine blood serum in 96-well plates. To each well, we added 100 μL of C. albicans, C. krusei, C. guilliermondii, or C. glabrata culture, and 0.2-400 μM farnesol. The microliter plates were cultured with the lid closed at 37°C for 48 h. Then, the liquid was removed, and the wells were washed 3 times with 200 μL phosphate buffer solution (pH 7.3). Biofilm fixation was performed using 150 μL of 96% ethanol for 15 min. Then, the microliter plates were dried for 20 min at 37°C, a 0.5% solution of crystalline violet was added, and the plates were placed in an incubator at 37°C. After 5 min, the contents of the wells were removed, washed 3 times with 200 μL of phosphate buffer solution (pH 7.2), and dried. The dye was extracted by washing with 200 μL of 96% ethanol for 30 min. The results were obtained using a photometric analyzer of enzyme immunoassay reactions at an optical density (OD) wavelength of 450 nm. Results: All of Candida spp. strains tested were susceptible to farnesol at concentrations ranging from 0.8 to 400 μM for C. albicans, C. krusei, and C. guilliermondii, and 12.5 to 400 μM for C. glabrata. Conclusion: This study provides new insights into the use of farnesol against biofilms produced by Candida species, but further studies in vivo are necessary to evaluate the effectiveness of the reduction of OD. To the best of our knowledge, the antimicrobial activity of farnesol against C. krusei, C. guilliermondii, and C. glabrata has not been reported previously, although studies have confirmed the inhibitory effect of farnesol on the growth of different microorganisms.


2020 ◽  
Vol 9 (3) ◽  
pp. 82
Author(s):  
Yuhui Ding

Loss in Ascorbic Acid contents of orange juice heated under different situations and pH was researched. In this experiment, Navanila oranges from Spain were squeezed and filtered by using a vacuum pump to make orange juice samples. These samples were extracted and make up with 0.1% Formic Acid in HPLC water, HPLC water and phosphate buffer solution (pH=6). Pasteurization was achieved at 60, 65 and 70℃ over 15, 25 and 35min period by using the water bath method and cooled to room temperature immediately. After that, Ascorbic Acid contents were analyzed by HPLC and 0.1% Formic Acid in HPLC water, HPLC water and phosphate buffer solution (pH=6) were used as mobile phases separately for their solutions. HPLC standard samples of Ascorbic Acid were prepared which means 0.1g Ascorbic Acid was weighted and then diluted into 50-250mg/ L solutions to make calibration lines for three solutions. The wavelength of Ascorbic Acid was 245nm but it changed to 296nm when samples in phosphate buffer solution (pH=6). Results showed that Ascorbic Acid concentration is more at 60℃ at 15min and there was a total decline trend with the increase of time and temperature. After statistics analysis, it has a significant affect (P<0.5) related to Ascorbic Acid contents with temperature and pH.


1985 ◽  
Vol 17 (10) ◽  
pp. 39-41 ◽  
Author(s):  
A. Schnattinger

Ten litres of tapwater were seeded with 200 µl (8×108 HAV particles) of a commercial (Organon Teknika) suspension of hepatitis A virus. Following WALTER and RÜDIGER (1981), the contaminated tapwater was treated with a two-stage technique for concentration of viruses from solutions with low virus titers. The two-stage technique consists of aluminium hydroxideflocculation (200 mg/l Al2(SO4)3. 18 H2O, pH 5,4-5,6) as first stage, the second stage of a lysis of aluminium hydroxidegel with citric acid/sodium citrate-buffer (pH 4,7; 1 ml/l sample), separation of viruses from the lysate by ultracentrifugation and suspension in 1 ml phosphate buffer solution (pH 7,2). A commercial solid phase enzyme-linked immunosorbent assay (ELISA) was used for the detection of HAV. HAV was detecterl in the 10.000:1 concentrates, but not in the seeded 101 samples. Approximately 4×108 of the inoculated 8×108 HAV particles were found in the 1 ml concentrates. The efficiency of detection is about 50%, the virus concentration 5000-fold. Although the percentage loss of HAV in comparison with concentration by means of membrane filtration is similar, the ultracentrifugation method yields a larger sample/concentrate ratio, so that smaller amounts of HAV can be detected more efficiently because of the smaller end-volume.


2019 ◽  
Vol 11 (30) ◽  
pp. 3866-3873 ◽  
Author(s):  
R. Karthikeyan ◽  
D. James Nelson ◽  
S. Abraham John

Selective and sensitive determination of one of the purine nucleotides, inosine (INO) using a low cost carbon dot (CD) modified glassy carbon (GC) electrode in 0.2 M phosphate buffer solution (pH 7.2) was demonstrated in this paper.


Sign in / Sign up

Export Citation Format

Share Document