ABSTRACT
A screen-printed carbon working electrode within a commercially available screen-printed three-electrode assembly was modified by using a composite of multiwalled carbon nanotubes (MWCNT) dispersed in polyethylenimine (PEI) followed by covering with the calf thymus dsDNA layer. Several electrochemical methods were used to characterize the biosensor and to evaluate damage to the surface-attached DNA: square wave voltammetry of the [Ru(bpy)(3)](2+) redox indicator and mediator of the guanine moiety oxidation, cyclic voltammetry and electrochemical impedance spectroscopy in the presence of the [Fe(CN)(6)](3-/4-) indicator in solution. Due to high electroconductivity and large surface area of MWCNT and positive charge of PEI, the MWCNT-PEI composite is an advantageous platform for the DNA immobilization by the polyelectrolyte complexation and its voltammetric and impedimetric detection. In this respect, the MWCNT-PEI interface exhibited better properties than the MWCNT-chitosan one reported from our laboratory previously. A deep DNA layer damage at incubation of the biosensor in quinazoline solution was found, which depends on the quinazoline concentration and incubation time.
Subject(s)
Biosensing Techniques , Carbon/chemistry , DNA Damage , Disposable Equipment , Nanotubes, Carbon/chemistry , Polyethyleneimine/chemistry , Quinazolines/chemistry , Animals , Cattle , DNA/analysis , Electric Conductivity , Electric Impedance , Electrochemistry , Electrodes , Electrolytes/chemistry , Reproducibility of Results , Sensitivity and Specificity , Surface Properties , Time FactorsABSTRACT
Multi walled carbon nanotubes (MWNT) in dimethylformamide (DMF) or aqueous sodium dodecyl sulfate (SDS) solution, colloidal gold nanoparticles (GNP) in phosphate buffer solution (PBS), and a GNP-MWNT mixture in aqueous SDS solution have been investigated for chemical modification of a screen-printed carbon electrode used as the signal transducer of a dsDNA-based biosensor. Differential pulse voltammetry of the DNA redox marker Co[(phen)3]3+ and the guanine moiety anodic oxidation and cyclic voltammetry with K3[Fe(CN)6] as indicator revealed substantial enhancement of the response of the biosensor, particularly when MWNT in SDS solution was used. The biosensor was used in testing of berberine, an isoquinoline plant alkaloid with significant antimicrobial and anticancer activity. Berberine had a very strong, concentration-dependent, effect on the structural stability of DNA from the human cancer cells (U937 cells) whereas non-cancer cells were changed only when berberine concentrations were relatively high 75 and 50 microg mL(-1).
Subject(s)
Berberine/chemistry , Biosensing Techniques/methods , DNA/analysis , DNA/chemistry , Electrochemistry , Nanostructures/chemistry , Neoplasms/chemistry , Cell Line, Tumor , Cobalt/chemistry , Humans , Molecular Structure , Neoplasms/genetics , U937 CellsABSTRACT
Our primary aim was to study berberine, a potential anti-cancer drug, for its cytotoxic and antiproliferative activity in-vitro using Ehrlich ascites carcinoma (EAC) cells. Cytotoxicity was measured by the growth inhibition assay. We investigated the effect of berberine on the biosynthesis of macro-molecules (DNA, RNA, proteins), cell cycle effects and induction of dsDNA damage and apoptosis in berberine-treated EAC cells. Our results showed that berberine acts cytotoxically on EAC cells. The cytotoxicity was directly concentration and time dependent. The highest cytotoxic concentrations (100 and 50 microg mL(-1)) induced intercalation of berberine with DNA, formation of dsDNA breaks, inhibition of DNA synthesis and death of EAC cells. A concentration of 10 mug mL(-1) induced clear apoptotic cell death, which was followed by inhibition of protein synthesis.
Subject(s)
Apoptosis , Berberine/pharmacology , DNA Damage , DNA, Neoplasm/biosynthesis , Animals , Carcinoma, Ehrlich Tumor , Cell Cycle , Cell Proliferation/drug effects , DNA/drug effects , Proteins/metabolism , RNA, Neoplasm/biosynthesis , Tumor Cells, CulturedABSTRACT
Quinazolines - 1,3-benzodiazines are biological active compounds, which are used in the phamaceutical industry, in agriculture and in the medicine. As documented in the literature, many derivatives demonstrated anticancer activity and they act as multitarget agents. 3-(5-Nitro-2-thienyl)-9-chloro-5-morpholin-4-yl[1,2,4]triazolo[4,3-c] quinazoline (NTCHMTQ) - a new synthetically prepared quinazoline derivative was the most effective derivative in our primary cytotoxic screening. In this study, we evaluated cytotoxic/antiproliferative activity of NTCHMTQ using human tumor cell line HeLa. Possible interaction of 3-(5-nitro-2-thienyl)-9-chloro-5-morpholin-4-yl[1,2,4]triazolo[4,3-c] quinazoline with calf thymus DNA was tested by the DNA - modified screen - printed electrode. Quinazoline derivative acted cytotoxically on tumor cell line HeLa. The IC(100) value was 10 microg/ml. The IC(50) values was found to be less than 4 microg/ml, a limit put forward by the National Cancer Institute (NCI) for classification of he compound as a potential anticancer drug. Quinazoline at micromolar concentrations induced morphological changes and necrosis of HeLa cells. Using the DNA based electrochemical biosensor, we have not found damage to DNA under in vitro conditions at an incubation of the biosensor in mixture with quinazoline.
