Construction of electrochemical DNA biosensors for investigation of potential risk chemical and physical agents

Simultaneous detection of purine metabolites by membrane modified electrochemical sensors

Purine metabolites are important for metabolic and cellular processes. Deregulation of purinergic signaling leads to pathological accumulation of purine degradation products in extracellular fluids and indicates various diseases. In clinical diagnosis at early stages of related diseases, accurate detection of Uric acid and Xanthine is of high importance. Electrochemical methods are fast, simple, sensitive, more convenient, and cost-effective compared to other analytical methods used in purine metabolites signaling. Electrochemical sensors are able to detect more compounds simultaneously. Modification of a glassy carbon electrode sensor with external protective membranes was used in this study to avoid unwanted signal interferences from analyte matrices. Polyvinyl alcohol, Chitosan, and Nafion membranes were selected for sensor modification to compare the electro-neutral, positive and negative charged setting of the Xanthine and Uric acid detection. All three membrane modified sensors showed adequate stability in the phosphate buffer solution after 5 min of incubation and are thus suitable for simultaneous detection of purine metabolites. The best results in anodic peak current response values were observed using the Nafion membrane modified glassy carbon electrode sensor. The approach reported here can be useful for the detection of purine metabolites from various matrices at early stages of clinical diagnosis.

Electrochemical Sensor Based on Poly(Azure B)-DNA Composite for Doxorubicin Determination

A new voltammetric DNA sensor has been developed for doxorubicin determination on the platform of a glassy carbon electrode (GCE) covered with electropolymerized Azure B film and physically adsorbed native DNA. The redox properties of polymeric Azure B were monitored at various pH and scan rates. DNA application decreased the peak currents related to polymeric and monomeric forms of the dye, whereas incubation in doxorubicin solution partially restored the peaks in accordance with the drug and DNA concentration. The relative shift of the cathodic peak current caused by doxorubicin depended on the nominal DNA concentration and its application mode. In optimal conditions, the DNA sensor makes it possible to determine between 0.1 μM to 0.1 nM doxorubicin (limit of detection 7×10-11 M). The DNA sensor was tested on commercial doxorubicin formulations and on artificial samples the mimicked electrolyte content of human serum.