细胞表面壳化的研究进展

细胞表面壳化主要是通过物理、化学等技术方法对细胞表面进行修饰,形成完整均匀的有机、无机、金属纳米粒子或者复合壳层结构,从而使不能自身壳化的生物细胞表面形成保护壳甚至赋予细胞新的功能,使细胞具备多功能性。近年来,此技术在细胞存储、细胞运输、细胞传感器、细胞芯片以及细胞治疗等方面应用广泛,发展迅速。本文综合目前的研究现状,详细介绍了可进行细胞表面壳化的细胞类型、生物表面壳化的方法以及人造细胞外壳的工程技术在生物医学以及能源环境中的应用等。     

Effect of the cell type and cell density on the binding of living cells to a silica particle: an atomic force microscope study

We used the atomic force microscope to study how the cell type and the density of cells adsorbed at a substrate can affect the adhesion between a living cell and a model drug delivery system (DDS) carrier nano-particle. We used three different anchorage-dependent cells, i.e., a living mouse fibroblast cell (L929), a living human colon cancer cell (Caco2), and a living mouse malignant melanoma cell (B16F10). For the DDS model nano-particle, we used a silica colloid. In order to correlate the adhesion force with the cell types, the growth curve of the cells were determined with a haemocytometer. The shapes of the cells at the different stages were monitored by light microscopy, and the morphology of their surfaces obtained by tapping mode atomic force microscopy.

Force measurements showed that the Caco2 cell bound little to a silica particle, regardless of the cell density. The L929 cell bound well to a silica particle for low and high cell densities. The B16F10 cell bound little to a silica particle for low cell densities, but bound well for high cell densities. AFM images showed that the L929 cell did not contain folds. The B16F10 cells, however, displayed folds in the cell surface for low cell densities, but no folds in the cell for high cell densities. As literature also reported that the Caco2 cell contains folds, these results suggested that cells with folds showed less adhesion to a silica particle than cells without folds. The presence of folds in the cell presumably decreased the number of sites on the cell that could hydrogen bond or undergo van der Waals binding with the silanol groups of the silica particle.     

Cell electrophoresis on a chip: what can we know from the changes in electrophoretic mobility?

An overview of both experimental and theoretical studies of cell electrophoresis mobility (EPM) over the past fifty years and the relevance of cell EPM measurement are presented and discussed from the viewpoint of exploring the potential use of cell EPM as an index of the biological condition of cells. Physical measurements of the optical and/or electrical properties of cells have been attracting considerable attention as noninvasive cell-evaluation methods that are essential for the future of cell-based application technologies such as cell-based drug screening and cell therapy. Cell EPM, which can be measured in a noninvasive manner by cell electrophoresis, reflects the electrical and mechanical properties of the cell surface. Although the importance of cell EPM has been underestimated for a long time, mostly owing to the technical difficulties associated with its measurement, recent improvements in measurement technology using microcapillary chips have been changing the situation: cell EPM measurement has become more reliable and faster. Recent studies using the automated microcapillary cell electrophoresis system have revealed the close correlation between cell EPM and important biological phenomena including cell cycle, apoptosis, enzymatic treatment, and immune reaction. In particular, the converged EPM distribution observed for synchronized cells has altered the conventional belief that cell EPMs vary considerably. Finding a new significance of cell EPM is likely to lead to noninvasive cell evaluation methods essential for the next-generation of cell engineering.     

Hybrid cell adhesive material for instant dielectrophoretic cell trapping and long-term cell function assessment

Dielectrophoresis (DEP) for cell manipulation has focused, for the most part, on approaches for separation/enrichment of cells of interest. Advancements in cell positioning and immobilization onto substrates for cell culture, either as single cells or as cell aggregates, has benefited from the intensified research efforts in DEP (electrokinetic) manipulation. However, there has yet to be a DEP approach that provides the conditions for cell manipulation while promoting cell function processes such as cell differentiation. Here we present the first demonstration of a system that combines DEP with a hybrid cell adhesive material (hCAM) to allow for cell entrapment and cell function, as demonstrated by cell differentiation into neuronlike cells (NLCs). The hCAM, comprised of polyelectrolytes and fibronectin, was engineered to function as an instantaneous cell adhesive surface after DEP manipulation and to support long-term cell function (cell proliferation, induction, and differentiation). Pluripotent P19 mouse embryonal carcinoma cells flowing within a microchannel were attracted to the DEP electrode surface and remained adhered onto the hCAM coating under a fluid flow field after the DEP forces were removed. Cells remained viable after DEP manipulation for up to 8 d, during which time the P19 cells were induced to differentiate into NLCs. This approach could have further applications in areas such as cell-cell communication, three-dimensional cell aggregates to create cell microenvironments, and cell cocultures.     

超临界流体制备微发泡聚合物材料的研究进展

以超临界流体为物理发泡剂制备的微发泡聚合物材料具有小的泡孔尺寸和高的泡孔密度,从而赋予材料优异的性能.本文首先阐述了微发泡聚合物材料的制备原理,以及聚合物微发泡过程中泡孔形成的四个阶段;基于这些认识,针对微发泡聚合物材料泡孔形态的改善,即增加泡孔密度、减小泡孔尺寸以及均化泡孔尺寸分布,从加强泡孔成核、控制泡孔增长的角度综述了近年来的研究进展;最后对如何有效控制泡孔形态提出了建议,并对微发泡聚合物材料的应用前景进行了展望.     

Significance of cell electrokinetic properties determined by soft-particle analysis in bacterial adhesion onto a solid surface

The influence of extracellular polymeric substances (EPSs) on bacterial cell electrokinetic properties and on cell adhesion onto glass beads in connection with bacterial cell electrokinetic properties was investigated using 12 heterotrophic bacterial strains. Bacterial cell surface properties such as the softness 1/lambda and charge density ZN were determined by Ohshima's soft-particle analysis using the measured electrophoretic mobility as a function of ionic strength. In 10 of 12 strains, when EPSs covering the cell surface were removed, the softness of the cell decreased, indicating that EPS adsorption enhanced the ease of liquid fluid in the ion-penetrable layer on the cell surface. On the other hand, the negative charge density of the cell surface increased for 9 of 12 strains, suggesting that EPSs covering the cell surface decreased the negative charge density of the cell surface layer. In addition, the characteristics of bacterial cell adhesion onto glass beads were evaluated by the packed-bed method and the data were interpreted to indicate cell adhesiveness. As a result, the efficiency of cell adhesion onto glass beads increased as negative cell surface potential psi0 decreased, whereas there seemed to be no correlation between zeta potential and cell adhesiveness. Cell surface potential psi0, which was derived by taking the bacterial polymer layer with EPSs into consideration, provided a more detailed understanding of the electrokinetic properties of bacterial cells.     

Bioelectrical Impedance Assay to Monitor Changes in Aspirin‐Treated Human Colon Cancer HT‐29 Cell Shape during Apoptosis

Abstract

Physiological cell death occurs primarily through an evolutionarily conserved form of cell suicide termed apoptosis, which may be triggered by cytokines, depletion of growth factors, or certain chemicals. It is morphologically characterized by severe alterations in cell shape like cell shrinkage and disintegration of cell–cell contacts. Aspirin and other nonsteroidal anti‐inflammatory drugs (NSAIDs) inhibit proliferation of human colon cancer cells in vitro. We applied a noninvasive bioelectrical impedance assay referred to as electric cell–substrate impedance sensing (ECIS) in order to monitor the apoptosis‐induced changes in human colon cancer HT‐29 cell shape in an integral and quantitative fashion with a time resolution on the order of minutes. In whole‐cell biosensors the cells are grown directly on the surface of small gold‐film electrodes. From readings of the electrical impedance of the cell‐covered electrode, we deduced alterations of aspirin on HT‐29 cells in cell–cell and cell–substrate contacts. And the apoptosis was verified by transmission electron microscope.     

Recent Progress and Perspectives on Cell Surface Modification

The cell membrane is a biological interface consisting of phospholipid bilayer, saccharides and proteins that maintains a stable metabolic intracellular environment as well as regulating and controlling the exchange of substances inside and outside the cell. Cell membranes provide a highly complex biological surface carrying a variety of essential surfaces ligands and receptors for cells to receive various stimuli of external signals, thereby inducing corresponding cell responses regulating the life activities of the cell. These surface receptors can be manipulated via cell surface modification to regulate cellular functions and behaviors Thus, cell surface modification has attracted considerable attention due to its significance in cell fate control, cell engineering and cell therapy. In this minireview, we describe the recent developments and advances of cell surface modification, and summarize the main modification methods with corresponding functions and applications. Finally, the prospect for the future development of the modification of the living cell membrane is discussed.     

交流阻抗法在细胞分析应用中的研究进展

交流阻抗法作为一种新型的无标记、全程动态、实时分析方法已在细胞研究中得到了广泛应用。本文综述了基于交流阻抗法进行细胞分析的研究新进展,重点对非法拉第阻抗谱法和法拉第阻抗谱法用于细胞分析的原理及应用进行了总结,主要包括交流阻抗法在细胞形态、细胞生长、细胞增殖、细胞凋亡以及作用于细胞的药效和毒性研究中的应用,并对其发展趋势进行了展望。     

Straightforward Cell Patterning with Ultra-Low Background Using Polydimethylsiloxane Through-Hole Membranes

Micropatterning is becoming an increasingly popular tool to realize microscale cell positioning and decipher cell activities and functions under specific microenvironments. However, a facile methodology for building a highly precise cell pattern still remains challenging. In this study, A simple and straightforward method for stable and efficient cell patterning with ultra-low background using polydimethylsiloxane through-hole membranes is developed. The patterning process is conveniently on the basis of membrane peeling and routine pipetting. Cell patterning in high quality involving over 97% patterning coincidence and zero residue on the background is achieved. The high repeatability and stability of the established method for multiple types of cell arrangements with different spatial profiles is demonstrated. The customizable cell patterning with ultra-low background and high diversity is confirmed to be quite feasible and reliable. Furthermore, the applicability of the patterning method for investigating the fundamental cell activities is also verified experimentally. The authors believe this microengineering advancement has valuable applications in many microscale cell manipulation-associated research fields including cell biology, cell engineering, cell imaging, and cell sensing.     

High‐Throughput Isolation of Cell Protrusions with Single‐Cell Precision for Profiling Subcellular Gene Expression

Invading cancer cells extend cell protrusions, which guide cancer‐cell migration and invasion, eventually leading to metastasis. The formation and activity of cell protrusions involve the localization of molecules and organelles at the cell front; however, it is challenging to precisely isolate these subcellular structures at the single‐cell level for molecular analysis. Here, we describe a newly developed microfluidic platform capable of high‐throughput isolation of cell protrusions at single‐cell precision for profiling subcellular gene expression. Using this microfluidic platform, we demonstrate the efficient generation of uniform cell‐protrusion arrays (more than 5000 cells with protrusions) for a series of cell types. We show precise isolation of cell protrusions with high purity at single‐cell precision for subsequent RNA‐Seq analysis, which was further validated by RT‐qPCR and RNA FISH. Our highly controlled protrusion isolation method opens a new avenue for the study of subcellular functional mechanisms and signaling pathways in metastasis.     

40Ah H_2/Ni空间储能电源充放电特性研究

组装40Ah氢镍电池,研究该空间储能电源充放电性能.结果表明,在环境温度0～10℃之间电池放电容量最高(达50A·h),放电过程电池温度升高10℃,过放电后,电池电压降至-0.2V左右,电池温度逐升,过充电时,电池电压先升后降,温度激升;该电池以57%DOD(depth of discharge)充放电,经循环2350次,放电电压仍可稳定于1.2V,电池电性能无减.     

Automatic medium exchange for micro-volume cell samples based on dielectrophoresis

Cell medium exchange is a crucial step for life science and medicine. However, conventional cell medium exchange methods, including centrifuging and filtering, show limited ability for micro-volume cell samples such as circulating tumor cell (CTC) and circulating fetal cell (CFC). In this paper, we proposed an automatic medium exchange method for micro-volume cell samples based on dielectrophoresis (DEP) in microfluidic chip. Fresh medium and cell suspension were introduced into the microfluidic channel as the laminar flow. Plane stair-shaped interdigital electrodes were employed to drive the cells from the cell suspension to fresh media directly by DEP force. Additionally, we characterized and optimized the cell medium exchange according to both the theory and experiments. In the end, we achieved a 96.9% harvest rate of medium exchange for 0.3 μL samples containing micro-volume cells. For implementing an automatic continuous cell medium exchange, the proposed method can be integrated into the automatic cell processing system conveniently. Furthermore, the proposed method is a great candidate in micro-volume cell analysis and processing, cell electroporation, single cell sequencing, and other scenarios.     

Sub-microlitre permittivity detectors for high-performance liquid chromatography

A theoretical model is developed for the response of permittivity detectors working at radiofrequency for h.p.l.c. applications. Three types of cell were tested: a coil cell, a parallel-ring cell and a two-wire intrusive cell. All offer small cell volumes (ca. 700 nl for the coil cell, 9 nl for the parallel-ring cell and 40 nl for the intrusive two-wire cell). The last cell, with a 20-MHz Franklin oscillator, is shown to be most useful for conventional and microbore h.p.l.c., offering low instrument noise and reasonable sensitivity. The model is shown qualitatively to describe the observed response well. The coil cell also offers the possibility of monitoring conductivity changes in electrolyte solutions through frequency-change measurements. The theoretical response function indicates that the oscillator frequency is proportional to the square root of the eluate conductivity.     

Studies on the origin of the voltammetric response of the PC-3 cell suspension

A novel experimental method was developed to study the origin of the voltammetric response of human prostate cancer (PC-3) cell suspension as a model in consideration of the biological characters of living cells. The presence of guanine and xanthine in the cell eluent secreted by the living cells was verified by HPLC assay with a DAD system and chemometric method. Comparative studies of voltammetric behaviors of the PC-3 cell suspension, the PC-3 cell eluent, and the PC-3 cell sediment re-suspension showed that the voltammetric response of the PC-3 cells was given by xanthine and guanine bases in the PC-3 cell eluent, not by the cells. Linear relationship between the peak currents of guanine and xanthine in the cell eluent and the cell concentrations was found. Other factors, such as the cell secretion time and the immersion time of the multiwalled carbon nanotubes modified glassy carbon electrode (MWCNTs-modified GCE) in the cell eluent, also influenced the intensity of the peak currents. The biochemical mechanisms of the voltammetric behavior for the cell suspension were proposed.     

Cell‐Surface Engineering by a Conjugation‐and‐Release Approach Based on the Formation and Cleavage of Oxime Linkages upon Mild Electrochemical Oxidation and Reduction

We report a strategy to rewire cell surfaces for the dynamic control of ligand composition on cell membranes and the modulation of cell–cell interactions to generate three‐dimensional (3D) tissue structures applied to stem‐cell differentiation, cell‐surface tailoring, and tissue engineering. We tailored cell surfaces with bioorthogonal chemical groups on the basis of a liposome‐fusion and ‐delivery method to create dynamic, electroactive, and switchable cell‐tissue assemblies through chemistry involving chemoselective conjugation and release. Each step to modify the cell surface: activation, conjugation, release, and regeneration, can be monitored and modulated by noninvasive, label‐free analytical techniques. We demonstrate the utility of this methodology by the conjugation and release of small molecules to and from cell surfaces and by the generation of 3D coculture spheroids and multilayered cell tissues that can be programmed to undergo assembly and disassembly on demand.     

Cytotoxic activity of antioxidant constituents from Hypericum triquetrifolium Turra

The Sulforodamine B (SRB) assay was used to test cytotoxicity against four human cancer cell lines and one normal cell line of antioxidant constituents isolated from Hypericum triquetrifolium Turra. Methanolic extract and pure compounds were tested against the large cell lung carcinoma cell line COR-L23, the hepatocellular carcinoma cell line HepG-2, renal cell adenocarcinoma ACHN, the amelanotic melanoma cell line C32 and normal human foetal lung MRC5. The results showed that I3-II8-biapigenin exhibited strong cytotoxic activity (IC50 = 5.73 micro g mL(-1)) showing a certain degree of selectivity against the different cell types.     

Real-time electrical impedance-based measurement to distinguish oral cancer cells and non-cancer oral epithelial cells

In this study, electrical impedance-based measurements were used to distinguish oral cancer cells and non-cancer oral epithelial cells based on their cellular activities on the microelectrodes in a real-time and label-free manner. CAL 27 and Het-1A cell lines were used as the models of oral cancer cells and non-cancer oral epithelial cells, respectively. Various cellular activities, including cell adhesion, spreading, and proliferation were monitored. We found that both the kinetics of cell spreading and the static impedance-based cell index were feasible to distinguish the two cell types. At each given cell number, CAL 27 cell spreading produced a smaller cell index change rate that was 60–70% of those of Het-1A cells. When cells were fully spread, CAL 27 cells generated a cell index more than four times greater than that of Het-1A cells. Since cell spreading and attachment occurs in the first few hours when they were cultured on the microelectrodes, this impedance-based method could be a rapid label-free and non-invasive approach to distinguish oral cancer cells from non-cancer oral epithelial cells. Cell viability analysis was performed along with the impedance-based analysis. Confocal microscopic imaging analysis showed the difference in cell morphology and the thickness of cell monolayers between the two cell types.     

SC-ICP-MS法测定金属元素的方法研究

为了使用单细胞电感耦合等离子体质谱(SC-ICP-MS)方法准确测定单个细胞中的铬(Cr)、锰(Mn)、铁(Fe)、铜(Cu)和锌(Zn)等多种内源性金属元素,该文基于动态反应池(DRC)模式对目标分析物的反应气流量和极杆抑制参数q(RPq)进行了优化,并研究了进样速度、细胞密度、驻留时间等因素对SC-ICP-MS检测的影响。分别采用细胞悬液直接进样、使用超声波探头使细胞悬液中的细胞破碎后进样和使用浓硝酸消解细胞后进样的ICP-MS测定结果对SC-ICP-MS定量结果的准确性进行验证分析。实验结果表明,可采用超声波破碎细胞的ICP-MS测定结果评估SC-ICP-MS测定的单细胞内Zn和Cu含量的准确性,采用酸消解细胞的ICP-MS检测结果验证单细胞内Fe和Cr的含量。缺少细胞标准物质时对SC-ICP-MS方法定量结果进行多角度验证是必要的。研究表明,使用SC-ICP-MS法可以较好地进行单细胞元素相关分析。