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We studied the electrochemical behaviour of adenine derivates (adenosine, 2-aminopurine, 2,6-diaminopurine, 6-benzyl-aminopurine, adenosine monophosphate, cyclic adenosine monophosphate, nicotinamide adenine dinucleotide, adenosine triphosphate, S-adenosyl-L-methionine, and synthetic derivatives AD-3, AD-6 and AD-9) using flow injection analysis with electrochemical detection using a glassy carbon electrode. The influences of pH, flow rate and potential on the signal height of the studied derivates were tested. The optimal pH was 3, the flow rate of the mobile phase 0.75 mLmin(-1) and the potential 1100 mV. Further, we attempted to characterize each of the studied derivatives by mathematical equations and classic analytical parameters. The lowest detection limit was estimated for adenine as 0.9 nM and 2-aminopurine as 0.5 nM.

The main aim of this paper is to utilize high performance liquid chromatography with electrochemical detection for determination of thiols content in plants tissues of lettuce treated with lead(II) ions (0, 0.5 and 1 mM). We used two HPLC-ED instruments: HPLC coupled with one channel amperometric detector and HPLC coupled with twelve channel coulometric detector to detect simultaneously twelve thiols. The detection limits of thiols measured by CoulArray detector were about two magnitudes lower in comparison to those measured by Coulochem III detector and were from tens to hundreds pM. Under the optimal conditions, we utilized HPLC-CoulArray detector for analysis of tissues from lettuce plants. In addition, distribution and accumulation of lead ions with high spatial resolution was monitored using laser induced breakdown spectroscopy.

Matrix metalloproteinases (MMP) belong to a group of zinc-dependent proteins that play a central role in the breakdown of extracellular matrices. Collagen, elastin, gelatin and casein are the main components of extracellular matrix cleaved by MMP. This paper aims to analyze the interaction between gelatinase B (MMP-9) and collagen using chronopotentiometric stripping analysis with adsorptive transfer stripping technique (AdTS CPSA). Under optimized experimental conditions (time accumulation of 90 s, supporting electrolyte 0.2 M acetate buffer pH 5, stripping current 1 μA), the detection limit (3 signal/noise) for MMP-9 was estimated as being 100 pM. The interaction between MMP-9 and collagen was studied according to the following scheme: i) HMDE surface was renewed. ii) Renewed surface of HMDE collagen (1 μg/mL) was accumulated for 90 s under open circuit. iii) The electrode was rinsed in ACS grade water and immersed in 5 μL drop of MMP-9. iv) The interaction between MMP-9 with collagen took place at open circuit. v) The electrode was then rinsed in ACS grade water. vi) The rinsed electrode was transferred into an electrochemical cell and measured in acetate buffer (pH 5). The CPSA signal of collagen after its interaction with MMP-9 increased more than 30% compared to that of only collagen. This increase in signal is likely due to the cleavage of collagen by MMP-9, hence its easy access to the electrode's surface.

The main aim of this work was to prepare and determine apoMT by adsorptive transfer stripping technique (AdTS) in connection with differential pulse voltammetry (DPV). Particularly, we investigated the electrochemical behavior of MT measured on the surface of hanging mercury drop electrode in the presence of sodium chloride as supporting electrolyte using AdTS DPV with respect to study the effects of MT signals by different concentrations and pH's of the electrolyte. Then, we aimed at utilizing this technique to observe changes in MTwhich are dependent on using strong chelating compounds ethylendiamine-N, N, N', N'-tetraacetic acid (EDTA). Thanks to ability of EDTA to bind heavy metals from active center of enzymes and regulation proteins, we were able to prepare apoMT; that means, MT without any metal ion bound in its structure. Detection limit of apoMT at very short time of accumulation (tA 120 s) was 3 nM (20 ng/mL and/or 15 fmol in 5 mL drop; RSD 2 -- 5%) estimated by dilution of the analyzed solution until the signal disappeared. In addition, it was possible to decrease detection limit by extending of time of accumulation of apoMT on the surface of HMDE. We were able to detect 30 pM of apoMT (200 pg/mL) at tA500 s.

As a consequence of the employment of platinum based cytostatic drugs in tumor diseases treatment, it became necessary not only to detect them in biological samples but also to determine and study the Pt-DNA adducts, which is highly important during investigation of resistance on antitumor treatment. Thus, the main objective of this work was to study the interactions between DNA and cisplatin. Primarily, we studied changes in electrochemical behavior of cisplatin in the presence of different concentrations of sodium chloride using differential pulse voltammetry. We found out that the highest signal of cisplatin was measured in 0.75 M NaCl with detection limit of 100 pM. The current accepted opinion about platinum based cytostatics mechanism of action is that the drugs induce their cytotoxic properties through binding to the nuclear DNA. That is why we followed by investigation of DNA interactions with cisplatin. For these purposes we have suggested a new biosensor, EDTA metallothionein modified hanging mercury drop electrode (EDTA MT biosensor) and used cyclic voltammetry as a comparative technique. The average concentration of the drug bound to DNA was estimated as 8.1 ng of cisplatin per 500 ng of DNA by EDTA MT biosensor. It follows from the results obtained that the suggested EDTA MT biosensor could be a new useful tool for investigation of interaction of DNA with cisplatin, because give a response only in the present of Pt(II)-DNA adduct.