Microfluidic methods for cell separation and subsequent analysis

Cell is the most basic unit of the morphological structure and life activity of an organism. Learning the composition, structure and function of cells, exploring the life activities of cells and studying the interaction between cells are of great significance for human cognition and control of the life activities of organisms. Therefore, rapid, convenient, inexpensive, high-precision and reliable methods of cell separation and analysis are being developed to obtain accurate information for the s...     

Tetrameric RGD induces clustering of integrin αvβ3 on the melanoma cell surface and decreases cell viability

The recombinant hybrid protein SR15 composed of streptavidin fused with RGD peptide is obtained. The ability of this protein to recognize human melanoma cells (MeWo line) is demonstrated. Types of expressed RGD-binding integrins in the cells of this line are identified. It is found that the recombinant hybrid protein SR15 binds to integrin αvβ3 on the surface of human melanoma cells. The binding to the protein SR15 results in clustering of αvβ3 receptors on the surface of MeWo cells, internalization of the recombinant protein, and an almost twofold decrease in cell viability.     

CellFacts II – single cell analysis in real time

CellFacts II integrates electrical flow impedance and fluorescence to determine the number, size and fluorescence characteristics of individual cells in a conductive fluid. The instrument has been optimised to detect and enumerate viable and non-viable cells in fluid samples with varied particulate content, i.e. total viable counts, with discrimination of the physiological status of the individual cells. The study shows the analysis of the physiological state of individual cells in a population, effectively in real-time, enabling the rapid determination of the effect of antimicrobial agents on these cells i.e. rapid determination and optimisation of antimicrobial agents in aqueous paint systems.     

Study on the discrete dielectrophoresis for particle–cell separation

This paper presents the application of the discrete dielectrophoretic force to separate polystyrene particles from red blood cells. The separation process employs a simple microfluidic device that is composed of interdigitated electrodes and a microchannel. The discrete dielectrophoretic force is generated by adjusting the duty cycle of the applied voltage. The electrodes make a tilt angle with the microchannel to change the moving direction of the red blood cells. By adjusting the voltage magnitude and duty cycle, we investigate the deflection of red blood cells and the variation of cell velocity along electrode edge under positive dielectrophoresis. The experiments with polystyrene particles show that the enrichment of the particles is greater than 150 times. The maximum separation efficiency is 97% for particle-to-cell number ratio equal to 1:2000 in the sample having high cell concentration. Using the appropriate applied voltage magnitude and duty cycle, the discrete dielectrophoretic force can prevent the clogging of microchannel while successfully separating the particles from the cells with high enrichment and efficiency. The proposed principle can be readily applied to dielectrophoresis-based devices for biomedical sample preparation or diagnosis such as the separation of rare or infected cells from a blood sample.     

Nanocoating of CsgA protein for enhanced cell adhesion and proliferation

Immune rejection, poor biocompatibility and cytotoxicity have seriously stalled the widespread application of biometallic materials. To overcome these problems, biometallic materials with fast and sufficient osseointegration, antibacterial properties and long-term stability have attracted the attention of researchers worldwide. Surface modification is currently used as a general strategy to develop material coatings that will overcome these challenging requirements and achieve the successful per...     

Brønsted acid-base ionic liquids for fuel cell electrolytes

A simple protic ionic liquid obtained from the combination of diethylmethylamine and trifluoromethanesulfonic acid exhibits the remarkable results as a medium temperature fuel cell electrolyte under non-humidifying conditions, affording a higher and stable open-circuit potential, wide liquid temperature range, and high thermal stability.     

Single-layer solar cell based on nanostructure of polyaniline on fluorine-doped tin oxide: a simple,low-cost and efficient FTO│n-PANI│Al cell

Nanostructure of polyaniline (n-PANI) is assembled to form a polymer solar cell on fluorine-doped tin oxide (FTO) and aluminum electrodes. The characterization and doping process of n-PANI are verified by ultraviolet–visible (UV–Vis) and Fourier transform infrared spectroscopies. The n-PANI conductivity is in the semiconductive range, and its contact resistance is determined by circular-TLM. The morphologies of n-PANI, FTO and n-PANI film deposited on FTO surface are investigated using atomic force microscopy, scanning electron microscope and transmission electron microscopy. The energy levels of HOMO and LUMO and band gap energy are obtained by cyclic voltammetry and UV–Vis spectroscopy. The similar results are found for band gap energy. The photovoltaic cell characteristics, i.e., open-circuit voltage (V_OC), short-circuit current density (J_SC), fill factor and power conversion efficiency (PCE or η), are evaluated by measuring the current density–voltage (J–V) under illumination condition and resistance measurements and are found to be 936 mV, 2.72 mA/cm², 0.377 and 1.6%, respectively, for FTO│n-PANI│Al structure. The mechanism of photoelectron conduction within the cell is studied by the electrochemical impedance spectroscopy. The results shows that not only FTO│n-PANI│Al cell is completely efficient (in comparison with other similar cells, PCE is relatively high), but also its fabrication is of low cost, simple, oxidation resistant and under the green condition.     

Does the chromatomembrane cell improve the quality of environmental analysis?

With the intention of combining partition chromatography and membrane techniques, we succeeded in developing the chromatomembrane cell which has proved to be reliable as an extraction and preconcentration manifold in flow injection analysis. With this technique, two immiscible phases can be induced to flow independently through a block of biporous (macro and micro) PTFE in order to promote analyte exchange. Consequently, the application of chromatomembrane cells in environmental analysis resolves all problems of sample pretreatment simply and effectively whenever a preconcentration step by gas/liquid or liquid/liquid solvent extraction is included. The link-up with analyzers (AAS, UV–Vis photometry, GC, IC, HPLC, voltammetry, ion selective electrodes, etc.) makes possible computer aided automization for environmental monitoring.     

Surveying selenium speciation from soil to cell—forms and transformations

The aim of this review is to present and evaluate the present knowledge of which selenium species are available to the general population in the form of food and common supplements and how these species are metabolized in mammals. The overview of the selenium sources takes a horizontal approach, which encompasses identification of new metabolites in yeast and food of plant and animal origin, whereas the survey of the mammalian metabolism takes a horizontal as well as a vertical approach. The vertical approach encompasses studies on dynamic conversions of selenium compounds within cells, tissues or whole organisms. New and improved sample preparation, separation and detection methods are evaluated from an analytical chemical perspective to cover the progress in horizontal speciation, whereas the analytical methods for the vertical speciation and the interpretations of the results are evaluated from a biological angle as well.     

A μL-scale micromachined microbial fuel cell having high power density

We report a MEMS (Micro-Electro-Mechanical Systems)-based microbial fuel cell (MFC) that produces a high power density. The MFC features 4.5-μL anode/cathode chambers defined by 20-μm-thick photo-definable polydimethylsiloxane (PDMS) films. The MFC uses a Geobacter-enriched mixed bacterial culture, anode-respiring bacteria (ARB) that produces a conductive biofilm matrix. The MEMS MFC generated a maximum current density of 16,000 μA cm(-3) (33 μA cm(-2)) and power density of 2300 μW cm(-3) (4.7 μW cm(-2)), both of which are substantially greater than achieved by previous MEMS MFCs. The coulombic efficiency of the MEMS MFC was at least 31%, by far the highest value among reported MEMS MFCs. The performance improvements came from using highly efficient ARB, minimizing the impact of oxygen intrusion to the anode chamber, having a large specific surface area that led to low internal resistance.     

Development of solid–oxide fuel cell for reduced operating temperatures

A technique for formation of electrolyte thin films with the thickness of 6–10 μm of zirconia stabilized by yttria (YSZ) is developed on the basis of the method of chemical deposition from the vapor phase of organometallic compounds (MOCVD). Planar electrochemical cells based on film electrolyte with a supporting anode with the working surface area of 12 cm² were manufactured. A solid-oxide fuel cell (SOFC) based on two fuel cells was developed and its life cycle tests at reduced operating temperatures (<800°C) were carried out for 400 h. The maximum power density reached in the SOFC tests was 316 mW/cm².     

Analytical characterization of cell–asbestos fiber interactions in lung pathogenesis

Asbestos is a fiber causing lung diseases such as asbestosis and mesothelioma. Although the process involving these diseases remains to be elucidated for developing drugs and treatments, direct consequences of fiber exposure in humans have been clearly demonstrated. These diseases are first characterized by histological heterogeneity and combine chronic inflammation with fibrosis and cellular alterations. As a consequence, asbestosis is usually diagnosed at advanced stages of the disease and treatments are usually inefficient to cure the patients. Here, we review the links established between asbestos fiber chemistry and morphology with the occurrence of associated lung diseases. Cytological and histological aspects of diseases are described with respect to current analytical capabilities, notably for microscopy techniques.     

Probability of cell transformation effect per mSv induced by α-particle radiation

Radiation carcinogenesis is one of the major biological effects considered to be important in risk assessment of radioactive exposures. The purpose of this work is to calculate the probability of cell transformation effect per mSv induced by α-particle radiation, from radon progeny, on sensitive cells of human lung. Probability was calculated by applying the analytical model cylindrical bifurcation (Jovanovi? et al., J Radioanal Nucl Chem 290(3):607–613, 2011) which was created to simulate the geometry of human airways with the geometric distribution of cell nuclei in the airway wall of the tracheobronchial tree. Cell transformation can change form or structure DNA, and this change cause that a normal cell undergoes as it becomes malignant. It is possible that radon is the number one cause of lung cancer among people who do not smoke. This analytical model of the human traheobronchial tree represent the extension of the ICRP66 (ICRP Human Respiratory Tract Model for Radiological Protection, 1994) model. Propagation of α-particle was simulated by Monte Carlo method. Reported probabilities are calculated for various targets and alpha particle energies. The sources included fast and slow mucus in BB and bb region. The targets are basal and secretory cells in BB region, and secretory cells in bb region. Results obtained in this work are unique.     

To what extent is the magnitude of the Cole-Cole α of the β-dielectric dispersion of cell suspensions explicable in terms of the cell size distribution?

The Cole-Cole α is a number that is often used to describe the divergence of a measured dielectric dispersion from the ideal dispersion exhibited by a Debye type of dielectric relaxation, and is widely assumed to be related to a distribution of the relaxation times in the system involved. The magnitude and relaxation time of the β-dielectric dispersion due to the charging of the plasma membrane capacitance of cell suspensions depend, inter alia, on the cell radius. An investigation was carried out to determine whether there might therefore be a relationship between the Cole-Cole α of the β-dispersion of yeast cell suspensions and the distribution of cell sizes. Changes in the Cole-Cole α during the batch culture of baker's yeast were recorded, showing an increase in the Cole-Cole α during the exponential phase (more than 0.3) relative to those of the lag phase (about 0.28) and the stationary phase (about 0.2). Although the cell size distribution, measured by flow cytometry, also showed an increase in breadth during the exponential phase, this was not strictly related to the changes in the Cole-Cole α observed. Further, the Cole-Cole α calculated from the measured cell size distribution was significantly smaller than that obtained experimentally. Simulations in which the internal conductivity or membrane capacitance per unit area of individual cells were allowed to vary substantially did not account for the “excessive” Cole-Cole α. Thus the magnitude of the Cole-Cole α of the β-dispersion of yeast cells cannot be ascribed simply to the charging of a static membrane capacitance in cells of differing sizes and/or internal conductivities.     

Mesoporous silica nanoparticles-assisted ruthenium(Ⅱ) complexes for live cell staining

Ruthenium complexes which can bind to DNA via electrostatic and intercalation interactions producing strong luminescence have become ideal candidates for DNA staining. However, some of them such as Ru(phen)_3Cl_2 and Ru(phen)_2(dppz)Cl_2 could hardly cross the cellular membrane of live cells which limited their further interaction with DNA in live cells. To solve this problem, a potential approach is to find a proper vehicle for loading and delivery of these ruthenium complexes into live cells.Mesoporous silica nanoparticles(MSNs) with non-toxicity and good biocompatibility can be good candidates. More importantly,ruthenium complexes with positively charge could be loaded on negatively charged MSNs via electrostatic attractions to form MSNs-Ru hybrid. In vitro test demonstrated that MSNs had no side effects on the interactions between Ru complexes and DNA.Furthermore, it is found that the MSNs-Ru hybrid can enter into living human cervical cancer cells HeLa and stain the DNA while the corresponding ruthenium complexes alone could hardly cross the cellular membrane in the control experiment, demonstrating MSNs can be employed to be an efficient ruthenium complexes delivery nanomaterial for live cell staining.     

Advanced electrocatalytic materials based biosensors for cancer cell detection – A review

Herein, we have highlighted the latest developments on biosensors for cancer cell detection. Electrochemical (EC) biosensors offer several advantages such as high sensitivity, selectivity, rapid analysis, portability, low-cost, etc. Generally, biosensors could be classified into other basic categories such as immunosensors, aptasensors, cytosensors, electrochemiluminescence (ECL), and photo-electrochemical (PEC) sensors. The significance of the EC biosensors is that they could detect several biomolecules in human body including cholesterol, glucose, lactate, uric acid, DNA, blood ketones, hemoglobin, and others. Recently, various EC biosensors have been developed by using electrocatalytic materials such as silver sulfide (Ag₂S), black phosphene (BPene), hexagonal carbon nitrogen tube (HCNT), carbon dots (CDs)/cobalt oxy-hydroxide (CoOOH), cuprous oxide (Cu₂O), polymer dots (PDs), manganese oxide (MnO₂), graphene derivatives, and gold nanoparticles (Au-NPs). In some cases, these newly developed biosensors could be able to detect cancer cells with a limit of detection (LOD) of 1 cell/mL. In addition, many remaining challenges have to be addressed and validated by testing more real samples and confirm that these EC biosensors are more accurate and reliable to measure cancer cells in the blood and salivary samples.     

Determination of bioelectrochemical parameters of red cell using a piezoelectric crystal sensor

Based on the impedance behavior of red cell at high frequency, the frequency response of series piezoelectric crystal sensor in the red cell suspension was derived and verified experimentally. A method of using piezoelectric crystal sensor to determine the conductivity of the interior of the cell was proposed. The experimental results show that the mean conductivity of rabbit red cell cytoplasm was 0.269 S/m and the mean shape factor of red cell was 2.05.     

Anode performance of Mn-doped ceria–ScSZ for solid oxide fuel cell

The 70 wt.% Mn-doped CeO₂ (MDC)-30 wt.% Scandia-stabilized zirconia (ScSZ) composites are evaluated as anode materials for solid oxide fuel cells (SOFCs) in terms of chemical compatibility, thermal expansion coefficient, electrical conductivity, and fuel cell performance in H₂ and CH₄. The conductivity of MDC10 (10 mol.% Mn-doping), MDC20, and CeO₂ are 4.12, 2.70, and 1.94 S cm⁻¹ in H₂ at 900 °C. With 10 mol.% Mn-doping, the fuel cells performances improve from 166 to 318 mW cm⁻² in H₂ at 900 °C. The cell with MDC10–ScSZ anode exhibits a better performance than the one with MDC20–ScSZ in CH₄, the maximum power density increases from 179 to 262 mW cm⁻². Electrochemical impedance spectra indicate that the Mn doping into CeO₂ can reduce the ohmic and polarization resistance, thus leading to a higher performance. The results demonstrate the potential ability of MDC10–ScSZ composite to be used as SOFCs anode.