Acetylcholinesterase (ChE) sensor based on Prussian blue (PB) modified electrode was developed and tested for the detection of organophosphorus and carbamic pesticides. The signal of the sensor was generated in PB mediated oxidation of thiocholine recorded at +200 mv in DC mode. ChE from electric eel was immobilized by cross-linking with glutaraldehyde in the presence of bovine serum albumin (BSA) on the surface of screen-printed carbon electrode covered with PB and Nafion. The content of the surface layer (specific enzyme activity, Nafion and BSA amounts) was optimized to establish high and reliable response toward the substrate and ChE inhibitors. The ChE/PB sensor makes it possible to detect Aldicarb, Paraoxon and Parathion-Methyl with limits of detection 30, 10 and 5 ppb, respectively (incubation 10 min). The feasibility of practical application of the ChE/PB sensor developed for the monitoring of degradation of the pesticides in wine fermentation was shown. To diminish matrix interferences, the electrolysis of the grape juice with Al anode and evaporation of ethanol were suggested, however the procedures decrease the sensitivity of pesticide detection and stability of the sample tested.
Cardiac myoglobin detection was based on direct electron transfer between the Fe(III)-heme and the electrode surface that was modified with metal nanoparticles stabilized by didodecyldimethylammonium bromide and antibodies. Gold, silver and copper nanoparticles were tested as catalysts of the Fe(III)/Fe(II) electrode process. All experiments were carried out with human blood plasma samples of healthy donors and patients with acute myocardial infarction. The method proposed does not require labeled secondary antibodies. Immunosensor has a detection limit of 5 ng/mL and a broad range of working concentrations. The whole procedure takes 20 minutes and can be used to establish the diagnosis of acute myocardial infarction.
A novel matrix based on commercially available carbon black (CB) N220 and didodecyldimethyl ammonium bromide (DDAB) was shown to be a reliable support for direct electron transfer reactions between screen printed electrode (SPE) and Fe(III)-heme proteins. Cytochrome c (cyt c), myoglobin (Mb), horseradish peroxidase (HRP) and cytochromes P450 (CYP 51A1, CYP 3A4, CYP 2B4) generated well-shaped cyclic voltammograms on SPE/CB/ DDAB electrodes (both in solution and in immobilized state). The attractive performance characteristics of CB modified electrodes are advantageous over single-walled carbon nanotubes (SW CNT) based ones. The achieved direct electrochemistry of heme proteins on CB/DDAB-modified electrodes provided successful elaboration of the immunosensor for cardiac Mb. The immunosensor showed applicability for diagnostics of myocardial infarction displaying significant difference in cardiac Mb content of human blood plasma samples taken from the corresponding patients.
Direct redox activity of different proteins was investigated on the surface of carbon screen printed electrodes (SPE). The signal attributed to the electrochemical oxidation of amino acid residues (cysteine (Cys), tryptophan (Trp) and tyrosine (Tyr)) was registered at Emax from 0.6 to 0.7 V (vs. Ag/AgCl). Based on the difference in the redox behavior of L‐tyrosine and 3‐nitro‐L‐tyrosine, the selective electrochemical detection of native and nitrated albumins was demonstrated. It was shown that the electrochemical signal correlated with the surface density of electroactive amino acid residues on the protein molecule. A simple electrochemical method for the total protein analysis was proposed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.