The Electroanalytical Performance of Sonogel Carbon Titanium (IV) Oxide Electrodes versus Conducting Polymer Electrodes in the Electrochemical Detection of Biological Molecules

The electrochemical performance of a newly developed sonogel carbon titanium (IV) oxide (SGC/TiO2 ) electrode against poly(3-methylthiophene) (P3MT) and poly(2,2\u27-bithiophene) (PBTP) modified electrodes in the electrochemical detection of biological molecules is reported. The stability of the Titanium (IV) Oxide coating on the sonogel carbon electrode was shown to be greater than the P3MT coating on the conventional size glassy carbon electrode. After 10 consecutive scans, there was a 21% loss of the initial signal at the P3MT modified electrode and a 5% loss of the initial signal at the SGC/TiO2 electrode. The influence of NAD+ on NADH response was tested. The PBTP modified electrode and bare electrode demonstrated the inability to stabilize the interference due to NAD+. The SGC/TiO2 electrode was able to detour the susceptibility to interfering NAD+. The response potential was improved by 141 mV. Response time for 5mM catechol (CAT) and 5mM ascorbic acid (AA) in 0.01M sulfuric acid was determined. Specificity for CAT detection was measured using a 5mM CAT + 5mM AA mixture in 0.01M sulfuric acid. The SGC/TiO2 electrode permits a shorter response time and improved selectivity for CAT. NADH was irreversible in all electrolytes. Highest anodic peak potential, at the PBTP modified electrode, was measured in sodium nitrate. Highest anodic peak potential at the SGC/TiO2 electrode was recorded in sulfuric acid

Applications of Capillary Electrophoresis for Studying Serum Albumin Enantioselection of D,L-Tryptophan Analogs

The pharmacokinetic difference between drug enantiomers is the impetus for developing analytical techniques to assess enantiomeric purity. Capillary electrophoresis (CE) is an analytical technique that is used for characterizing drug-protein binding. The pitfall to using CE for drug-protein binding studies is protein chiral selectors tend to adsorb onto capillary walls and cause changes in electroosmotic flow that lead to decreased enantioselection and migration time irreproducibility between consecutive injections. The experimental parameters for minimizing the adverse effects of protein adsorption are not clear from the literature. Rinsing protocols to improve enantioselection and migration time repeatability were developed using the tryptophan-bovine serum albumin system as a model. The enantioselection of bovine serum albumin (BSA) could be improved by: 1) increasing separation voltage; 2) using sample buffer ionic strength at least 3 orders of magnitude less than the separation buffer; 3) limiting the equilibration time with separation buffer; and 4) allowing for protein diffusion. Rinsing the capillary with sodium hydroxide, followed by water improved migration time repeatability RSD from 24.7% to 1.8% (n = 4). Drug-protein binding is contingent upon the three dimensional structure of the binding site, and the presence of other competing drug molecules. Drug-drug displacement is difficult to predict and the effects of protein glycation on binding of drugs is not well defined. To highlight the use of CE for addressing questions of biochemical interest, CE was applied to characterize drug-drug displacement and the effects of protein glycation on the enantioselection of drugs by BSA. The tryptophan-bovine serum albumin, 5-fluoro-tryptophan-bovine serum albumin, and 5-hydroxy-tryptophan-bovine serum albumin systems were used as models. A CE method for studying competitive binding was established using ibuprofen as the displacer molecule. Accurate calculation of selectivity was found to depend on the precomplexation of ibuprofen and BSA. A CE method for studying the effects of protein glycation was developed using BSA containing different degrees of glycation as chiral selectors. The enantioselection of tryptophan analogs by BSA was altered by glycation as reported in other analytical methods. These studies can serve as guidelines for optimizing serum albumin enantioselection and extending its use in other biopharmaceutical applications

The Electroanalytical Performance of Sonogel Carbon Titanium (IV) Oxide Electrodes versus Conducting Polymer Electrodes in the Electrochemical Detection of Biological Molecules

The electrochemical performance of a newly developed sonogel carbon titanium (IV) oxide (SGC/TiO2 ) electrode against poly(3-methylthiophene) (P3MT) and poly(2,2\u27-bithiophene) (PBTP) modified electrodes in the electrochemical detection of biological molecules is reported. The stability of the Titanium (IV) Oxide coating on the sonogel carbon electrode was shown to be greater than the P3MT coating on the conventional size glassy carbon electrode. After 10 consecutive scans, there was a 21% loss of the initial signal at the P3MT modified electrode and a 5% loss of the initial signal at the SGC/TiO2 electrode. The influence of NAD+ on NADH response was tested. The PBTP modified electrode and bare electrode demonstrated the inability to stabilize the interference due to NAD+. The SGC/TiO2 electrode was able to detour the susceptibility to interfering NAD+. The response potential was improved by 141 mV. Response time for 5mM catechol (CAT) and 5mM ascorbic acid (AA) in 0.01M sulfuric acid was determined. Specificity for CAT detection was measured using a 5mM CAT + 5mM AA mixture in 0.01M sulfuric acid. The SGC/TiO2 electrode permits a shorter response time and improved selectivity for CAT. NADH was irreversible in all electrolytes. Highest anodic peak potential, at the PBTP modified electrode, was measured in sodium nitrate. Highest anodic peak potential at the SGC/TiO2 electrode was recorded in sulfuric acid