Constrution Of Carbon-based Electrodes Modified With Organics Containing Carboxy Group And Their Application In Cytotoxicity Detection

Cell electrochemical method gets rapid development in the field of in vitro biological detection due to its simpleness and high-efficience. However, electrochemical detection of cells has been depending on nano-materials modified electrode and m L-scale electrolytic cell, and the high cost limits its widely application. This paper focuses on developing a new kind of organics modified electrodes and miniaturized electrochemical devices for detection of cells voltammetric behaviour and drug screening.Poly calcein modified glassy carbon electrode(PCA/GCE) has been constructed based on the optimal conditions of scanning cycles 20, p H7.4 and polymerization potential-1.4~1.8 V. Its electrocatalytic activity toward the oxidations of xanthine(XA), guanine(G), adenine(A) and hypoxanthine(HX) were investigated. Simultaneous measuremen of uric acid(UA), XA and HX on PCA/GCE were carried out. The results show that PCA/GCE displays excellent electrocatalytic activity on simultaneous determination of UA, XA and HX. The linear ranges for simultaneous detections of UA, XA and HX are 0.20~80, 0.20~80 and 0.50~90 μmol/L with the detection limits of 0.12, 0.12 and 0.30 μmol/L, respectively. Moreover, PCA/GCE is highly selective towards the determination of these analytes in the present of coexisting interferents with high concentrations. PCA/GCE was applied in simultaneous detection of UA, XA and HX in human urine with recovery percent of 96.0%~107.0%.PCA/GCE was applied to detect the electrochemical behavior of MCF-7 cells. Two voltammetric signals of MCF-7 cells ascribe to oxidation of xanthine/guanine and hypoxanthine/adenine were detected on PCA/GCE due to high sensitivity provided by PCA. The maximum voltammetric signals of MCF-7 cells can be found under the condition of accumulation time 200 s, accumulation potential-0.1 V and p H 7.4. Two independent nonlinear exponent relationships between peak current and cell concentration were obtained simultaneously in the wide concentration range of 3.0 × l03~ 7.0 × l06 cells/m L, which obey the index equation Ipa =7.458-6.415exp(- C/52380)(R2 = 0.986) for xanthine/guanine and Ipa = 4.023- 3.773 exp(- C/228700)(R2 = 0.984) for hypoxanthine/adenine with the low detection limit of 3000 cells/m L, respectively.Two signals of MCF-7 cells were applied to evaluate cytotoxicity of cyclophosphamide(CTX). With the increase of CTX concentrations, peak current tendency of both two signals exhibited a different degree decreasing, indicating a dose-dependent relationship. The MTT assay was performed to verify the reliability of electrochemical method. The maximum inhibitory rates based on electrochemical signalⅠand signalⅡ were 58.4% and 69.4%, and the value obtained from MTT was 59.2%.Poly(threonine) modified pencil electrodes(PT/PGE) was presented. Electrochemical behaviors of purine on PT/PGE were studied. Based on the high catalytic efficiency of PT/PGE, a mini-electrochemical system was constructed for determination of trace level of cell samples. The mini-electrochemical analytical device was proved to be practicable by comparing cyclic voltammetry characteristics of [Fe(CN)6]3-/4- from the traditional electrochemical cell and mini-electrochemical device, respectively, and the mini-electrochemical device reduced usage of cell samples more than 90% from traditional electrochemical device.The system was used for study on electrochemical behavior of MCF-7 cells based on microliter level of cells. Electrochemical response of MCF-7 cells was most powerful under the condition of accumulation time 480 s, potential-1V and p H 7.4. A nonlinear exponent relationship between peak current and the cell concentration range from 3.0 ×l03 to 7.0×l06 cells/m L was established with the index equation Ipa = 59.557 exp(-C/1.709) – 71.486(R2 = 0.954). Finally, the system was used for evaluating the cytotoxicity of CTX on MCF-7 cells.An electrochemical micro-detection system combined pencil graphite electrode array modified by carbon nanotube and threonine composite was build(MT/PGEA). Electrochemical behaviors of purine on MT/PGEA were studied. Catalytic activities order of four electrodes toward to oxidation of purine are MT/PGEA > MT/PGE > PT/PGE > PGE. The detection limits are 0.025,0.025,0.050 and 0.050 μmol/L for XA, G, A and HX, which preliminarily demonstrate the feasibility of this system for detecting trace of cells.