Electrochemical antitumor drug sensitivity test for leukemia K562 cells at a carbon-nanotube-modified electrode

The change in electrochemical behavior of tumor cells induced by antitumor drugs was detected by using a multiwall carbon nanotubes (MWNTs)-modified glass carbon electrode (GCE). Based on the changes observed, a simple, in vitro, electrochemical antitumor drug sensitivity test was developed. MWNTs promoted electron transfer between the electroactive centers of cells and the electrode. Leukemia K562 cells exhibited a well-defined anodic peak of guanine at +0.823 V at 50 mV s(-1). HPLC assay with ultraviolet detection was used to elucidate the reactant responsible for the electrochemical response of the tumor cells. The guanine content within the cytoplasm of each K562 cell was detected to be 920 amol. For the drug sensitivity tests, 5-fluorouracil (5-FU) and several clinical antitumor drugs, such as vincristine, adriamycin, and mitomycin C, were added to cell culture medium. As a result, the electrochemical responses of the K562 cells decreased significantly. The cytotoxicity curves and results obtained corresponded well with the results of MTT assays. In comparison to conventional methods, this electrochemical test is highly sensitive, accurate, inexpensive, and simple. The method proposed could be developed as a convenient means to study the sensitivity of tumor cells to antitumor drugs.     

Magnetic immobilization and electrochemical detection of leukemia K562 cells

A new protocol was proposed for rapid magnetic isolation, immobilization and electrochemical detection of leukemia K562 cells via their decoration with cationic magnetic nanoparticles (CMNPs). The CMNPs (3-aminopropyltriethoxysilane-treated Fe₃O₄) were synthesized in liquid solution and characterized by transmission electron microscopy. After the incubation of pre-cultured leukemia K562 cells in the coexistence of CMNPs for a period of time, the CMNPs modified living cells could be rapidly isolated from the medium and immobilized firmly on the electrode surface via a magnetic field, as traced by quartz crystal microbalance. The cyclic voltammetric experiments of the cells immobilized at glassy carbon electrode exhibited an irreversible anodic current peak whose height is proportional to cell viability, and the 5-fluorouracil cytotoxicity results obtained from the proposed magnetic-electrochemical method were supported by conventional MTT assays. The proposed method is simple, rapid, inexpensive, and convenient in electrode renewal, which is recommended as a promising experimental platform for wider applications in biosensing and cellular researches.     

A self-assembled monolayer based electrochemical immunosensor for detection of leukemia K562A cells

A novel strategy to quantify the cell number of leukemia K562A cells using electrochemical immunosensor was developed by effective surface immunoreaction between P-glycoprotein (P-gp) on cell membrane and P-gp mouse monoclonal antibody bound on an epoxysilane monolayer modified glassy carbon electrode. The surface morphologies of the epoxysilane monolayer and the bound antibodies were studied with atomic force microscopy. The binding of target K562A cells onto the immobilized antibodies increased the electron-transfer impedance of electrochemical probe, which depended linearly on the cell concentration in the range of 5.0 × 10⁴–1.0 × 10⁷ cells mL⁻¹. The detection limit of the immunosensor was 7.1 × 10³ cells mL⁻¹. The proposed strategy showed acceptable reproducibility with an RSD of 3.4% for the linear slope and good precision with the RSD of 3.7% and 3.0% examined at the cell concentrations of 2.0 × 10⁶ and 1.0 × 10⁷ cells mL⁻¹.     

Electrochemical synthesis of polyaniline nanocomposite based on modified gold nanoparticles and its application for electrochemical aptasensor

Journal of Solid State Electrochemistry - The method of synthesis of polyaniline, as an important conductive polymer, and the conjugated metal nanomaterials applied in the polymer, determines the...     

超氧化物歧化酶在纳米金/L-半胱氨酸修饰金电极上的电化学行为

通过L-半胱氨酸将纳米金修饰到金电极上,把超氧化物歧化酶(SOD)固定在修饰电极表面,制备了SOD-纳米金/L-半胱氨酸修饰电极。运用交流阻抗法、循环伏安法等方法表征了该电极,发现SOD在该电极上于0.15V和-0.05V左右产生较明显的氧化还原峰,在0.04～0.24V/s扫描速率范围内,其还原峰电流与扫描速速呈线性关系,表明该电极过程受吸附控制。研究了H2O2对SOD-纳米金/L-半胱氨酸修饰电极伏安行为的影响,发现该电极的还原峰电流与H2O2浓度在1.0×10-6～2.0×10-4mol/L范围内呈良好的线性关系,相关系数为-0.996,可用于对H2O2的分析检测。     

Direct application of gold nanoparticles to one-pot electrochemical biosensors

Gold nanoparticles (AuNPs) have been widely employed for the fabrication of electrochemical biosensors. In most cases, AuNPs are immobilized on the surface of an electrode, so they are difficult to be regenerated, making the use of the biosensor unfriendly. In this work, by adopting AuNPs directly as the electrolytes, we have developed a novel AuNPs-based electrochemical detection system. In brief, AuNPs-catalyzed oxidation of glucose is combined with a HRP-catalyzed reaction as well as an electrocatalytic reaction to compose cascade reactions in the electrolyte. Thus, the intensity of the electrocatalytic signals has quantitative relation with the concentration of glucose, and favors the sensitive detection of glucose. Furthermore, because the catalysis of AuNPs may be blocked under the interaction with single-stranded DNA and unblocked in the presence of a complementary sequence, detection of DNA and even single-nucleotide polymorphism can thereby been achieved. This one-pot detection system can be operated and regenerated very easily, since all the components are integrated in the electrolytes of AuNPs, and the unmodified electrode can be reused after being rinsed. This concept by integrating the advantages of sensitive electrochemical detection with the easy-to-operate nanocolloidal system may also promote the development of other kinds of electrochemical biosensors.     

Fabrication and electrochemical application of three-dimensional gold nanoparticles: self-assembly

Multilayers film of nanostructured citrate-stabilized gold particles (AuNPs) has been fabricated based on the layer-by-layer (LBL) technique using a self-assembled monolayer of 1,4-benzenedimethanethiol (BDMT). The formation of AuNPs and BDMT self-assemblies as alternative multilayers was confirmed by transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), and quartz crystal microbalance (QCM). The formation of uniform AuNP layers with an average monolayer thickness of 5-6 nm was obvious in the TEM images. The existence of BDMT molecules as cross linkers for the AuNPs' layers was proved by XPS measurements. The greater affinity of AuNPs' layers to bind BDMT molecules in comparison with the bare Au bulk electrode was revealed by QCM measurements. Electrochemically, the AuNPs' layers on the electrode surface did not only catalyze the reduction of oxygen (ca. 100-mV positive shift of the reduction peak potential compared with that at the bare Au bulk electrode) but also showed a fascinating nature of working as a renewed activated-electrode surface; a zigzag response was observed for oxygen reduction during alternative immobilization of BDMT and the AuNP layer. The self-assembly of a new AuNPs layer restored the catalytic activity that was entirely blocked by the preceding BDMT layer.     

Polyaniline doped with modified gold nanoparticles and its electrochemical properties in neutral aqueous solution

Doping polyaniline with COO(-)-modified gold nanoparticles by forming stable layer-by-layer multilayer films can shift its electroactivity to neutral pH. The films can electrocatalyze the oxidation of NADH and offer potential applications in other fields, e.g., optoelectronics or biosensing.     

Synthesis and electrochemical applications of gold nanoparticles

This review covers recent advances in synthesis and electrochemical applications of gold nanoparticles (AuNPs). Described approaches include the synthesis of AuNPs via designing and choosing new protecting ligands; and applications in electrochemistry of AuNPs including AuNPs-based bioelectrochemical sensors, such as direct electrochemistry of redox-proteins, genosensors and immunosensors, and AuNPs as enhancing platform for electrocatalysis and electrochemical sensors.     

血红蛋白在纳米金修饰电极上的电化学研究

氧化还原蛋白在电极上的直接电化学研究不但能获得有关蛋白质和酶的热力学和动力学性质等重要信息,为开发新型生物传感器和生物反应器提供理论指导,而且对了解它们在生命体内的电子转移机理和生理作用机制具有重要意义。血红蛋白(Hb)是以血红素为辅基的蛋白质,在生物体中的主要     

Hetarylfuroxans: cytotoxic effect and induction of apoptosis in chronic myeloid leukemia K562 cells

Russian Chemical Bulletin - Hetarylfuroxans (4-(2-methylpyridin-5-yloxy)-3-phenylfuroxan (1), bis(1,2,4-oxadiazol- 3-yl)furoxan (2), and 4-amino-3-(indenotriazin-3-yl)furoxan (3)) exhibit in vitro...     

Properties of gold electrode modified with dimercaptosuccinic acid and electrochemical behavior of copper histidine complex

A self-assembled monolayer of meso-2,3-dimercaptosuccinic acid was prepared on the surface of gold disc electrode. The modified electrode was characterized using cyclic voltammetry in copper(II) solution and cyclic voltammetry and electrochemical impedance spectroscopy in the presence of potassium hexacyanoferrate( II)/(III) and hexaammineruthenium (II)/(III) chloride. Binding of copper(II) histidine complex (Cu–His) onto the electrode was successfully achieved for a wide range of tested concentrations, as shown with adsorption transfer stripping voltammetry. Electrode response (logΔI_p) was linearly proportional to logc(Cu–His) with correlation coefficient R³² = 0.9839.     

Fabrication of layer-by-layer modified multilayer films containing choline and gold nanoparticles and its sensing application for electrochemical determination of dopamine and uric acid

A novel electrochemical sensor has been constructed by use of a glassy carbon electrode (GCE) coated with a gold nanoparticle/choline (GNP/Ch). Electrochemical impedance spectroscopy (EIS), field emission scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the properties of this modified electrode. It was demonstrated that choline was covalently bounded on the surface of glassy carbon electrode, and deposited gold nanoparticles with average size of about 100 nm uniformly distributed on the surface of Ch. Moreover, the modified electrode exhibits strong electrochemical catalytic activity toward the oxidation of dopamine (DA), ascorbic acid (AA) and uric acid (UA) with obviously reduction of overpotentials. For the ternary mixture containing DA, AA and UA, these three compounds can be well separated from each other, allowing simultaneously determination of DA and UA under coexistence of AA. The proposed method can be applied to detect DA and UA in real samples with satisfactory results.     

半乳糖保护的Au纳米颗粒的制备及性能研究

通过一种简易的方法,利用D-半乳糖胺和氯金酸制备出了能够用于肝癌细胞靶向识别的Au纳米颗粒探针.该纳米颗粒形貌和尺寸均一并且生物相容性良好.通过改变反应体系的pH能够对Au纳米颗粒的尺寸进行调控.此外,这种新型的纳米颗粒对RCA120还具有超高的检测灵敏度,实验结果显示其检测限度可以达到2μg·L^-1.     

芦丁在纳米金修饰玻碳电极上的电化学行为及其测定

采用循环伏安法将纳米金电沉积于玻碳电极表面,制备了纳米金修饰玻碳电极(NG/GCE).在pH3.29的Britton-Robinson(B-R)缓冲溶液中,用循环伏安法研究了芦丁在NG/GCE上的电化学行为.结果表明,NG/GCE对芦丁的氧化还原反应有良好的电催化作用.用方波伏安法测得芦丁的还原峰电流与其浓度在2.0×10-8～2.0×10-6mol/L范围内呈线性关系,检出限为1.0×10-8mol/L(S/N=3).     

Ensembles of nanoelectrodes modified with gold nanoparticles: characterization and application to DNA-hybridization detection

A new method to increase the active area (A _act) of nanoelectrode ensembles (NEEs) is described. To this aim, gold nanoparticles (AuNPs) are immobilized onto the surface of NEEs using cysteamine as a cross-linker able to bind the AuNPs to the heads of the nanoelectrodes to obtain the so-called AuNPs-NEEs. The analysis of the cyclic voltammograms recorded in pure supporting electrolyte showed that the presence of the nanoparticles reflects in an, approximately, ten-times increase in the electrochemically active area of the ensemble. The measurement of the amount of electroactive polyoxometalates, which can be adsorbed on the gold surface of NEEs vs. AuNPs-NEEs, confirmed a significant increase of active area for the latter. These evidences indicate that there is a good electronic connection between the AuNPs and the underlying nanoelectrodes. The possibility to exploit AuNPs-NEEs for biosensing application was tested for the case of DNA-hybridization detection. After immobilization on the gold surface of AuNPs-NEEs of a thiolated single-stranded DNA, the hybridization with complementary sequences labeled with glucose oxidase (GOx) was performed. The detection of the hybridization was achieved by adding to the electrolyte solution the GOx substrate (i.e., glucose) and a suitable redox mediator, namely the (ferrocenylmethyl) trimethylammonium (FA⁺) cation; when the hybridization occurs, an electrocatalytic increase of the oxidation current of FA⁺ is recorded. Comparison of electrocatalytic current recorded at DNA modified NEEs and AuNPs-NEEs indicate, for the latter, a significant increase in sensitivity in the detection of the DNA-hybridization event.     

Assembly process of CuHCF/MPA multilayers on gold nanoparticles modified electrode and characterization by electrochemical SPR

Gold nanoparticles were deposited onto 2-mercaptoethylamine (MEA)-assembled planar gold thin film to construct gold nanoparticles modified electrode by virtue of a solution-based self-assembly strategy. Subsequently, 3-mercaptopropionic acid (MPA)-bridged copper hexacyanoferrate (CuHCF) multilayers were constructed on the as-prepared gold nanoparticles modified electrode. The resulted multilayer nanostructures were investigated by electrochemical surface plasmon resonance (EC-SPR) and atomic force microscopy (AFM) with primary emphasis upon the effect of the gold nanoparticles on the MPA/CuHCF multilayers growth and their surface morphology. Compared with the multilayer system on a planar gold electrode, the different electrochemical and optical properties might result from higher curvature effect and extraordinary surface-to-volume ratio characteristic of gold nanoparticles and the nanoparticle-selective growth of CuHCF. A dendrimer-like assembly process was proposed to explain the experiment results. This new motif of multilayer on the gold nanoparticles modified electrode was different from that of on a planar gold electrode, indicating a potential application of EC-SPR technique in the study of nanocomposite materials.     

Detection and distinguishability of leukemia cancer cells based on Au nanoparticles modified electrodes

The Au nanoparticles (Au NPs) modified interface has been fabricated by multi-potential step electrodeposition in this study. Based on the nano-Au interface, we have proposed an electrochemical approach to detect the cancer cell numbers sensitively with a detection limit of about 500 cells. More interestingly, the drug sensitive leukemia K562 cells and drug resistant leukemia K562/adriamycin could be electrochemically distinguished on the interface by the oxidation potential, which did not show any evident differences on the bare electrode. These results indicate the promising application of this nano-interface for constructing the unlabeled potential-discriminative cell biosensors.     

Shape- and size-dependent refractive index sensitivity of gold nanoparticles

Gold nanoparticles of different shapes and sizes, including nanospheres, nanocubes, nanobranches, nanorods, and nanobipyramids, were dispersed into water-glycerol mixtures of varying volume ratios to investigate the response of their surface plasmon peaks to the refractive index of the surrounding medium. The refractive index sensitivities and figures of merit were found to be dependent on both the shape and the size of the Au nanoparticles. The index sensitivities generally increase as Au nanoparticles become elongated and their apexes become sharper. Au nanospheres exhibit the smallest refractive index sensitivity of 44 nm/RIU and Au nanobranches exhibit the largest index sensitivity of 703 nm/RIU. Au nanobipyramids possess the largest figures of merit, which increase from 1.7 to 4.5 as the aspect ratio is increased from 1.5 to 4.7.