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.     

Electrochemical study of brucine on an electrode modified with magnetic carbon-coated nickel nanoparticles

A novel type of glassy carbon electrode modified with magnetic carbon-coated nickel nanoparticles (C-Ni/GCE) was fabricated and the electrochemical properties of brucine were studied using it. The carbon-coated nickel nanoparticles showed excellent electrocatalytic activity for the redox of brucine and an enhanced electron transfer rate. The electrochemical behavior of brucine on the C-Ni/GCE was explored by cyclic voltammetry (CV), and a redox mechanism for brucine was proposed. A series of electrochemical parameters were calculated for brucine by CV and controlled-potential electrolysis. The C-Ni/GCE showed good sensitivity, selectivity and stability, and was applied to determine the concentration of brucine. The differential pulse voltammetry (DPV) response of the C-Ni/GCE showed that the catalytic current was linear with the concentration of brucine in the range of 4.7 × 10⁻⁸ to 2.4 × 10⁻⁴ mol l⁻¹, with a correlation coefficient of 0.998. The detection limit was 1.4 × 10⁻⁸ mol l⁻¹.     

Effect of surface charge and agglomerate degree of magnetic iron oxide nanoparticles on KB cellular uptake in vitro

We synthesized three types of magnetic iron oxide nanoparticles (MNPs), which were meso-2,3-dimercaptosuccinic acid (DMSA) coated MNPs (DMSA@MNPs, 17.3 ± 4.8 nm, negative charge), chitosan (CS) coated MNPs (CS@MNPs, 16.5 ± 6.1 nm, positive charge) and magnetic nanoparticles agglomerates, formed by electronic aggregation between DMSA@MNPs and CS (CS-DMSA@MNPs, 85.7 ± 72.9 nm, positive charge) respectively. The interactions of these MNPs with Oral Squamous Carcinoma Cell KB were investigated. The results showed that cellular uptakes of MNPs were on the dependence of incubation time, nanoparticles concentration and nanoparticles properties such as surface charge, size, etc. The cellular uptake was enhanced with the increase of incubation time and nanoparticles concentration. Although all MNPs could enter to cells, we observed apparent differences in the magnitude of nanoparticles uptaken. The cellular uptake of CS-DMSA@MNPs by KB cells was the highest and that of DMSA@MNPs was the lowest among the three types of MNPs. The same conclusions were drawn via the reduction of water proton relaxation times , resulting from the different iron load of labeled cells using a 1.5 T clinical MR imager. The finding of this study will have implications in the chemical design of nanomaterials for biomedical applications.     

Impact and mechanism of TiO2 nanoparticles on DNA synthesis in vitro

The impact of TiO₂ nanoparticles on DNA synthesis in vitro in the dark and the molecular mechanism of such impact were studied. The impact of TiO₂ nanoparticles on DNA synthesis was investigated by adding TiO₂ nanoparticles in different sizes and at various concentrations into the polymerase chain reaction (PCR) system. TiO₂ nanoparticles were premixed with the DNA polymerase, the primer or the template, respectively and then the supernatant and the precipitation of each mixture were added into the PCR system separately to observe the impact on DNA synthesis. Sequentially the interaction between TiO₂ nanoparticles and the DNA polymerase, the primer or the template was further analyzed by using UV-visible spectroscopy and polyacrylamide gel electrophoresis (PAGE). The results suggest that TiO₂ nanoparticles inhibit DNA synthesis in the PCR system in the dark more severely than microscale TiO₂ particles at the equivalent concentration and the inhibition effect of TiO₂ nanoparticles is concentration dependent. The molecular mechanism of such inhibition is that in the dark, TiO₂ nanoparticles interact with the DNA polymerase through physical adsorption while TiO₂ nanoparticles do with the primer or the template in a chemical adsorption manner. The disfunction levels of the bio-molecules under the impact of TiO₂ nanoparticles are in the following order: the primer > the template > the DNA polymerase. Supported by the National Natural Science Foundation of China (Grant Nos. 50572074 & 50673078), the Shanghai Key Fundamental Project (Grant No. 06JC14068) and the Innovation Program of Shanghai Municipal Education Commission (Grant No. 08ZZ21)     

In vitro macrophage uptake and in vivo biodistribution of long-circulation nanoparticles with poly(ethylene-glycol)-modified PLA (BAB type) triblock copolymer

The effect of the PEG-grafted degree in the range of 0–30% on the in vitro macrophage uptake and in vivo biodistribution of poly(ethylene glycol)–poly(lactic acid)–poly(ethylene glycol) (PELE) nanoparticles (NPs) were investigated in this paper. The prepared NPs were characterized in terms of size, zeta potential, hydrophilicity, poly(vinyl alcohol) (PVA) residual on nanoparticles surfaces as well as drug loading. The macrophage uptake and biodistribution including plasma clearance kinetics following intravenous administration in mice of the NPs labeled by 6-coumarin were evaluated. The results showed that, except for the particles size, the hydrophilicity, superficial charges and in vitro phagocytosis amount of NPs are dependent on the PEG content in the copolymers greatly. The higher of the PEG content, the more hydrophilicity and the nearer to neutral surface charge was observed. And the prolonged circulation half-life (t_1/2) of the PELE NPs in plasma was also strongly depended on the PEG content with the similar trend. In particular for PELE30 (containing 30% of PEG content) NPs, with the lowest phagocytosis uptake accompanied the highest hydrophilicity and approximately neutral charge, it had the longest half-life in vivo with almost 12-fold longer and accumulation in the reticuloendothelial system organs close to 1/2-fold lower than those of reference PLA. These results demonstrated that the PELE30 NPs with neutral charge and suitable size has a promising potential as a long-circulating oxygen carrier system with desirable biocompatibility and biofunctionality.     

5(6)-Carboxyfluorescein diacetate as an indicator of Caenorhabditis elegans viability for the development of an in vitro anthelmintic drug assay

A new in vitro assay for anthelmintic activity using Caenorhabditis elegans is based on the ability of 5(6)-carboxyfluorescein diacetate (CFDA) to indicate the worm's viability. It is shown for the first time that the treatment of a suspension of worms with a solution of 5(6)-carboxyfluorescein diacetate (4.2%) for 30 min transiently induces fluorescence in dead worms only, allowing a fast and efficient determination of the proportion of dead worms by fluorescence microscopy.

The proposed test has been validated using mixtures of populations of living and killed C. elegans and proved to be selective, linear in the range 0–100%, accurate and precise.

The suitability of the assay to detect anthelmintic activity was then evaluated by studying the toxicity against C. elegans of a series of known anthelmintic compounds (mebendazole, levamisole, niclosamide, pyrantel, piperazine, and thiabendazole) with various modes of action.

The worms were exposed to each drug at two concentrations, 50 and 100 μg/ml for piperazine, niclosamide, pyrantel and 5 and 10 μg/ml for the others. We observed that, in the tested range of doses, piperazine and niclosamide were only moderately toxic, yielding 13.1 and 17.5% of dead worms; due to their mode of action and/or specificity, the low toxicity of these compounds was as expected. The marked activities of all the other compound fully agree with those described in the literature and obtained by other more laborious techniques.

These validation data indicate that the proposed in vitro anthelmintic assay using 5(6)-carboxyfluorescein diacetate allows for sensitive measurement of worm viability.     

Fluorescence microscopy-based analysis of apoptosis induced by platinum nanoparticles against breast cancer cells

In recent years, capping molecules onto the surface of nanomaterials has become an interesting field of research. This idea facilitates the biological applications of nanomaterials with a modified surface. Keeping this in mind, the present study addresses the development of polymeric platinum nanoparticles using polyvinyl pyrrolidone (PVP). High-throughput characterization indicates that polymeric platinum nanoparticles have an excellent surface morphology and good dispersity in aqueous solution. More specifically, high resolution-transmission electron microscopy studies showed that the polymeric platinum nanoparticles were spherical and measured 2–10 nm. Furthermore, the polymeric platinum nanoparticles were evaluated for anticancer properties against human MCF-7 breast cancer cell lines. The results show that polymeric platinum nanoparticles inhibited the growth of cancer cells in a dose-dependent manner with a half-maximum inhibitory concentration of 96.36 μg ml⁻¹. In addition, fluorescence-based staining methods confirmed an inquest in the pattern of cell death inferring late apoptotic bodies, nuclear fragmentation, mitochondrial membrane potential and generation of reactive oxygen species. The overall findings suggest that the polymeric platinum nanoparticles confer anticancer activity and may be suitable chemotherapeutic agents in the future. Finally, the results from this study can be extended to other types of cancer as well.     

Identification of live liver cancer cells in a mixed cell system using galactose-conjugated fluorescent nanoparticles

Bio-functioned fluorescent silica nanoparticles have been synthesized for cell labeling and cell differentiation and have shown great promise as novel fluorescent probes. The galactose-conjugated fluorescent nanoparticles (GCFNPs) have been obtained by the conjugation of amino-modified fluorescent silica nanoparticles with lactobionic acid (LA) through EDAC linkage. The GCFNPs retain excellent biological activity and can be used in bioanalysis as an immunofluorescence assay. The specific identification of target cells from the background cells have been directly demonstrated in a simple model system by a laser confocal scanning microscope, because the specific and non-specific labeling can simultaneously visualized in a given microscopic field of view. The flow cytometric analysis has proved that GCFNPs can effectively recognize target cells in the mixed cell system. The demonstration of precise identification of few liver cancer cells in the blood confirmed the excellent capability of GCFNPs in identifying specific cells in a large host cell background. The nanoparticle's excellent photostability, good biocompatibility and significant signal amplification make them well-suited for the identification of individual cells sensitively for a variety of biomedical studies such as cancer metastasis and stem cell progeny in vivo.     

Quantitative study of cellular heterogeneity in doxorubicin uptake and its pharmacological effect on cancer cells

Cellular heterogeneity in doxorubicin (DOX) uptake and its relationship with pharmacological effect on cancer cells were quantitatively investigated for the first time. An in vitro experimental model was established by treating human leukemia K562 and breast cancer MCF‐7 cells with different schedules of DOX with or without surface P‐glycoprotein (P‐gp) inhibitor verapamil (VER). The cellular heterogeneity in DOX uptake was quantitatively examined by single‐cell analysis using capillary electrophoresis coupled with laser‐induced fluorescence detection. The corresponding cytotoxic effect was tested by cellular morphology, 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐tetrazolium and flow cytometry assays. The expression of cellular membrane surface P‐gp was determined by flow cytometry. Results showed that the cellular heterogeneity exists in DOX uptake. The single‐high DOX schedule leads to lower uptake heterogeneity and higher mean drug uptake. The cellular heterogeneity in DOX uptake was found to be negatively correlated with drug cytotoxicity and surface P‐gp expression, with r = ?0.7680 to ~ ?0.9587. VER reduces the cellular variation in DOX uptake, suggesting that surface P‐gp may be one of the causes of the cellular heterogeneity in DOX uptake. This research demonstrates the importance of quantitative study of cellular heterogeneity in drug uptake and its potential application in drug schedule design, response prediction and therapy modulation. Copyright © 2014 John Wiley & Sons, Ltd.     

SDS对镍在HNO3/Cl-/H2O体系中电化学振荡行为的影响

阴离子表面活性剂十二烷基硫酸钠(SDS)能够控制金属镍在0.5 mol•L-1 HNO3/0.005 mol•L-1 Cl-/H2O溶液中的电流振荡行为. 在电流振荡过程中, 镍电极微分电容和电导等均出现明显的振荡特性. 随着SDS浓度的增大, 镍表面微分电容和溶液电导振幅等值均逐渐减小. 并且对SDS在镍电流振荡和钝化过程中的作用原理给予解释.     

Nanostructured electrochemical DNA biosensors for detection of the effect of berberine on DNA from cancer cells

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 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 μg mL⁻¹. Figure Schematic illustration of preparation of the nanostructured films: (a) layer-to-layer coverage (DNA/nanomaterial/SPE); (b) mixed coverage (DNA-nanomaterial/SPE)     

Real-time tracking of hydrogen peroxide secreted by live cells using MnO2 nanoparticles intercalated layered doubled hydroxide nanohybrids

We report a facile and green method for the fabrication of new type of electrocatalysts based on MnO₂ nanoparticles incorporated on MgAl LDH P-type semiconductive channel and explore its practical applications as high-performance electrode materials for electrochemical biosensor. A series of MgAl layered doubled hydroxide (LDH) nanohybrids with fixed Mg/Al (M²⁺/M³⁺ atomic ratio of 3) and varied amount of MnCl₂.4H₂O are fabricated by a facile co-precipitation method. This approach demonstrates the combination of distinct properties including excellent intercalation features of LDH for entrapping nanoparticles and high loading of MnO₂ nanoparticles in the host layers of LDH. Among all samples, Mn5–MgAl with 0.04% loaded manganese has a good crystalline morphology. A well-dispersed MnO₂ nanoparticles encapsulated into the host matrix of hydrotalcite exhibit enhanced electrocatalytic activity towards the reduction of H₂O₂ as well as excellent stability, selectivity and reproducibility due to synergistic effect of good catalytic ability of MnO₂ and conductive MgAl LDH. Glass carbon electrode (GCE) modified with Mn5–MgAl possesses a wide linear range of 0.05–78 mM, lowest detection limit 5 μM (S/N = 3) and detection sensitivity of 0.9352 μAmM⁻¹. This outstanding performance enables it to be used for real-time tracking of H₂O₂ secreted by live HeLa cells. This work may provide new insight in clinical diagnosis, on-site environmental analysis and point of care testing devices.     

Preparation and electrochemical behaviors of platinum nanoparticles impregnated on binary carbon supports as catalyst electrodes of direct methanol fuel cells

Binary carbon-supported platinum (Pt) nanoparticles were prepared by a chemical reduction method of Pt precursor on two types of carbon materials such as carbon blacks (CBs) and graphite nanofibers (GNFs). Average sizes and loading levels of Pt metal particles were dependent on a mixing ratio of two carbon materials. The highest electroactivity for methanol oxidation was obtained by preparing the binary carbon supports consisting of GNFs and CBs with a weight ratio of 30:70. Furthermore, with an increase of GNFs content from 0% to 30%, a charge-transfer resistance changed from 19 Ohm cm² to 11 Ohm cm². The change of electroactivity or the resistance of catalyst electrodes was attributed to the changes of specific surface area and morphological changes of carbon-supported catalyst electrodes by controlling the mixing ratio of GNFs and CBs.     

Visual detection of cancer cells by colorimetric aptasensor based on aggregation of gold nanoparticles induced by DNA hybridization

A simple but highly sensitive colorimetric method was developed to detect cancer cells based on aptamer–cell interaction. Cancer cells were able to capture nucleolin aptamers (AS 1411) through affinity interaction between AS 1411 and nucleolin receptors that are over expressed in cancer cells, The specific binding of AS 1411 to the target cells triggered the removal of aptamers from the solution. Therefore no aptamer remained in the solution to hybridize with complementary ssDNA-AuNP probes as a result the solution color is red. In the absence of target cells or the presence of normal cells, ssDNA-AuNP probes and aptamers were coexisted in solution and the aptamers assembled DNA-AuNPs, produced a purple solution. UV–vis spectrometry demonstrated that this hybridization-based method exhibited selective colorimetric responses to the presence or absence of target cells, which is detectable with naked eye. The linear response for MCF-7 cells in a concentration range from 10 to 10⁵ cells was obtained with a detection limit of 10 cells. The proposed method could be extended to detect other cells and showed potential applications in cancer cell detection and early cancer diagnosis.     

Electrochemical approach for monitoring the effect of anti tubulin drugs on breast cancer cells based on silicon nanograss electrodes

One of the most interested molecular research in the field of cancer detection is the mechanism of drug effect on cancer cells. Translating molecular evidence into electrochemical profiles would open new opportunities in cancer research. In this manner, applying nanostructures with anomalous physical and chemical properties as well as biocompatibility would be a suitable choice for the cell based electrochemical sensing. Silicon based nanostructure are the most interested nanomaterials used in electrochemical biosensors because of their compatibility with electronic fabrication process and well engineering in size and electrical properties. Here we apply silicon nanograss (SiNG) probing electrodes produced by reactive ion etching (RIE) on silicon wafer to electrochemically diagnose the effect of anticancer drugs on breast tumor cells. Paclitaxel (PTX) and mebendazole (MBZ) drugs have been used as polymerizing and depolymerizing agents of microtubules. PTX would perturb the anodic/cathodic responses of the cell-covered biosensor by binding phosphate groups to deformed proteins due to extracellular signal-regulated kinase (ERK^1/2) pathway. MBZ induces accumulation of Cytochrome C in cytoplasm. Reduction of the mentioned agents in cytosol would change the ionic state of the cells monitored by silicon nanograss working electrodes (SiNGWEs). By extending the contacts with cancer cells, SiNGWEs can detect minor signal transduction and bio recognition events, resulting in precise biosensing. Effects of MBZ and PTX drugs, (with the concentrations of 2 nM and 0.1 nM, respectively) on electrochemical activity of MCF-7 cells are successfully recorded which are corroborated by confocal and flow cytometry assays.     

Fabrication of a novel impedance cell sensor based on the polystyrene/polyaniline/Au nanocomposite

Gold nanoparticles (AuNPs) were assembled on the surface of polystyrene (PS) and polyaniline (PANI) core-shell nanocomposite (PS@PANI) for the immobilization of HL-60 leukemia cells to fabricate a cell electrochemical sensor. The immobilized cells exhibited irreversible voltammetric response and increased the electron transfer resistance with a good correlation to the logarithmic value of concentration ranging from 1.6 × 10³ to 1.6 × 10⁸ cells mL⁻¹ with a limit of detection of 7.3 × 10² cells mL⁻¹ at 10σ. This biosensor was simple, low cost and disposable, which implied that the PS@PANI/Au composites can regard as the potential applications for clinical applications.     

Impact of Arsenic Trioxide on LS-174T Cell Growth and the Activity of Telomerase

The therapeutic action of arsenic trioxide（ As203 ） on solid tumors has aroused widespread interest among scholars. To study the impact of As2O3 on human colorectal carcinoma cells（ LS-174T cell） and the activity of telomerase, the methods of PCR-ELISA, flow cytometry （FCM） and MTT assay in vitro were utilized. The results show that （1） with an increase in the concentration of As2O3, the ratio of living the cells to dead cells decreases significantly, and the IC50 value is 5.23 μg/mL; （2） the cells of the experimental groups can endure a series of morphological changes similar to the features of apoptosis ; （3） the apoptotic curves of FCM pictures appear after 24 h, and the cells show the apoptosis in a time-dependent manner; （4） As2O3 can inhibit the activity of telomerase of the cell extraction obviously in a concentration-dependent and time-dependent manner after 24 h. It can be concluded from the experiment results in vitro that As2O3 can induce the apoptosis of LS-174T cells and inhibit the telomerase activity. Therefore, it has been proposed, for the first time, that these two factors （the apoptosis of LS-174T cells and the inhibition to the telomerase activity） are important causes of the LS-174T cell death caused by As2O3.     

硝酸锶对原代培养的小鼠成骨细胞增殖、分化和矿化功能的影响

采用噻唑蓝(MTT)法、碱性磷酸酶(ALP)比活性测定、油红O染色、Ⅰ型胶原测定以及矿化结节染色及定量分析等方法,研究了不同浓度的硝酸锶对原代培养的成骨细胞增殖、分化、矿化功能以及横向分化为脂肪细胞的影响。结果表明:硝酸锶对成骨细胞增殖、分化、矿化功能以及横向分化为脂肪细胞的影响与作用浓度和时间密切相关,但没有呈现出剂量依赖性。结果提示,硝酸锶对骨代谢的影响是复杂的,其具有保护还是损害作用取决于作用浓度和时间,而且它们是影响硝酸锶生物效应(从损伤到保护)转变的关键因素。