SYNTHESIS, STRUCTURE AND ANTIOXIDANT ACTIVITY (4S, 5S) -2- (1'-BROM-2'-PHENYLVINYL) -3,4-DIMETHYL-5-PHENYL-1,3-OXAZOLIDINE

На основе соединения [S-(R*,R*)]-α-[1-(Метиламино)этил]бензолметанола и α-бромциннамальдегида синтезирован соответствующий 1,3-оксазолидин, строение которого доказано методом ЯМРН спектроскопии, а также изучено влияние его на процесс электровосстановления кислорода (ЭВ О) в различных концентрациях. В качестве метода оценки применена катодная вольтамперометрия на ртутно-пленочном электроде, отражающая количество активных форм кислорода нейтрализованных антиоксидантом за определенное время. Показано, что водный раствор (4S,5S)-2-(1’-бром-2’-фенилвинил)-3,4-диметил-5-фенил-1,3-оксазолидин проявляет антиоксидантную активность в широком диапазоне концентраций. Based on the compound [S- (R*,R*)]-α-[1-(Methylamino)ethyl]benzenemethanol and α-bromocinnamaldehyde, the corresponding 1,3-oxazolidine was synthesized, the structure of which was proved by H NMR spectroscopy, and its effect on the process of electroreduction of oxygen (ER O) in various concentrations. Cathodic voltammetry on a mercury-film electrode, reflecting the amount of reactive oxygen species neutralized by an antioxidant for a certain time, was used as an assessment method. It was shown that an aqueous solution of (4S, 5S)-2-(1'-bromo-2'-phenylvinyl)-3,4-dimethyl-5-phenyl-1,3-oxazolidine exhibits antioxidant activity in a wide range of concentrations.

Optimization of the electrochemical pre-concentration of trivalent lanthanum from aqueous media

Electrochemical pre-concentration has been shown to effectively increase sample sensitivity and decrease processing time; however, the basic mechanism and optimal conditions of the technique remain unknown, specifically for lanthanides. To gain a better understanding of the mechanism of action, the aqueous solution conditions required to maximize the electrochemical pre-concentration of lanthanum (La) were studied. Parameters investigated included pH, applied potential, and ionic strength. To further optimize and elucidate the mechanism of lanthanide pre-concentration, specific interactions of lanthanum with the mercury film electrode were studied. Three possible mechanisms were proposed based on preliminary observations, including ligand bridging, hydroxide formation, and amalgamation.

An Electrochemical Mercuric Ion Sensor Based on CdS Nanparticle Label

In the present study, we describe an electrochemical sensor for Hg2+ detection by using the DNA probe. Two specific sequence for the probes, one has to ensure that the probe A hybridized with probe B modified on CdS nanoparticle to form stable DNA duplexes only in the presence of Hg2+ at a given operating temperature. After dissolving the CdS particles from the electrode, a mercury-film electrode was used for electrochemical detection of these Cd2+ ions which offered sensitive electrochemical signal transduction.The limit of detection of this assay in buffer is 12 nM. The detection was also specific for Hg2+ without being affected by the other metal ions, such as Cd2+,Li+,Ba2+,K+,Ca2+.

An Electrochemical Biosensor for Detection of Thrombin based on Displacement Mode

A sensitive electrochemical biosensor for detection of thrombin based on target protein-induced strand displacement is presented. For this proposed biosensor, dsDNA which was prepared by the hybridization reaction of the immobilized probe ssDNA (IP) containing thiol group and thrombin aptamer base sequence was initially immobilized on the Au electrode by self-assemble via Au-S bind, and a DNA labeled with PdS nanoparticles (DP-PdS) was used as a detection probe. When the so prepared dsDNA modified Au electrode was immersed into a solution containing target protein and DP-PdS, the aptamer in the dsDNA give priority to to form G-quarter structure with the present target protein and the dsDNA sequence was released one single strand and returned to IP strand which consequently hybridized with DP-PdS. After dissolving the captured PdS particles from the electrode, a mercury-film electrode was used for electrochemical detection of these Pd2+ ions which offered sensitive electrochemical signal transduction. The peak current of Pd2+ ions had a good linear relationship with the thrombin concentration in the range of 7.3×10−8–7.3×10-11 mol/L and the detection limit was 2.3×10-11 mol/L of thrombin. The detection was also specific for thrombin without being affected by the coexistence of other proteins, such as BSA and lysozyme.

A New Electrochemical Aptasensor for Protein Detection Based on Target Protein-Induced Strand Displacement

A sensitive electrochemical aptasensor for detection of thrombin based on target protein-induced strand displacement is presented. For this proposed aptasensor, dsDNA which is from immobilized probe DNA (IP) which has a hybridized with aptamer(Apt) initially was immobilized on the Au electrode through thiol group of IP，while a DNA labeled with PdS nanoparticles was used as a detection probe (DP-PdS). When Au electrode immersed into solution which contain target protein and DP-PdS, the aptamer preferred to form G-quarter structure with the present target protein and dsDNA was released into immobilized probe DNA (IP) which could be hybridized with DP-PdS. After dissolving PdS from electrode, a mercury-film electrode was used for electrochemical detection of these Pd2+ ions which offered excellent electrochemical signal transduction. Detection of thrombin was specific without being affected by the coexistence of other proteins such as BSA and lysozyme, and as low as 2.3×10-11 mol/L of thrombin was detected.