Cell behavior, monitoring

It is possible to monitor pH variation by adding a pH indicator. The compound most used is phenol red, which is rose-colored at pH 7.8, red at pH 7.4, orange at pH 7.0, and yellow at pH 6.5. Nevertheless, it is convenient to point out that most commercially available phenol red contains impurities that could influence cell behavior. Also, this compound can interfere with the interpretation of experimental data obtained by the use of fluorescence and absorbance techniques. 

Cherlet M, Marc A (1998), Intracellular pH monitoring as a tool for the study of hybridoma cell behavior in batch and continuous bioreactor cultures, Biotechnol. Prog. 14 626-638. 

In this connection, I would like to cite three examples of chemical engineering challenges in biotechnology where, while an understanding of cell behavior is needed, it is the basic chemical engineering research that will likely make the difference. One example is from plant cell culture, the second from antibiotic production, and the third from biotechnology monitoring and control. 

Taken together, the combined QCM-ECIS approach provides the experimental options to follow attachment, spreading, cytoskeletal reorientation and cellular differentiation for barrier-forming cell types in a single experimental setup. Since the data is recorded from one and the same cell mono-layer, the individual time courses of either parameter provide additional clues for a correct interpretation of the data. The electrochemical ECIS approach provides a lot more experimental options that have not been addressed in this article. These will help to broaden our understanding of QCM readings for adherent animal cells and guide us in the development of additional cell-based assays in which the QCM is used as a transducer to monitor cell behavior. 

Chung H A, Kato K, Itoh C, et al. (2004). Casual cell surface remodeling using biocompatible lipid-poly (ethylene glycol) (n) Development of steal cells and monitoring of cell membrane behavior in serum-supplemented conditions. J. Biomed. Mater. Res. 70A 179-185. 

I. Giaever and C.R. Keese, Use of Electric Fields to Monitor the Dynamical Aspect of Cell Behavior in Tissue Culture, IEEE Transactions on Biomedical Engineering, no. 2, pp. 242-247, 1986. 

Giaever, I., and Keese, C. R., Use of electric fields to monitor the dynamical aspects of cell behavior in tissue culture, IEEE Trans, Biotned, Eng., 33, 242-247 (1986). 

Cells behaviors under mechanical strains have been of great interest, but conventional mechano-transaction is too large to monitor single cells. Akbari et al. fabricated DE into arrays of 100 pm by 200 pm sized actuators. These actuators will stretch uniaxially when voltages are applied and provide the stretching to cells (Akbari and Shea 2012) (See Fig. 27). 

Dynamic Cell Behavior. While not as well-explored as sensors and drug delivery systems, dynamic cell behavior can also be investigated using EAPs. Cell motility, motion, and proliferation can be monitored. For example, DNA-functionalized EAPs can be used to monitor genetic mutations (399). Direct detection of DNA hybridization has been accomplished with a hinctionalized polyp3u -role (400). 

The interest in vesicles as models for cell biomembranes has led to much work on the interactions within and between lipid layers. The primary contributions to vesicle stability and curvature include those familiar to us already, the electrostatic interactions between charged head groups (Chapter V) and the van der Waals interaction between layers (Chapter VI). An additional force due to thermal fluctuations in membranes produces a steric repulsion between membranes known as the Helfrich or undulation interaction. This force has been quantified by Sackmann and co-workers using reflection interference contrast microscopy to monitor vesicles weakly adhering to a solid substrate [78]. Membrane fluctuation forces may influence the interactions between proteins embedded in them [79]. Finally, in balance with these forces, bending elasticity helps determine shape transitions [80], interactions between inclusions [81], aggregation of membrane junctions [82], and unbinding of pinched membranes [83]. Specific interactions between membrane embedded receptors add an additional complication to biomembrane behavior. These have been stud-... 

A small (25-kg), portable apheresis system, available in 1993, is designed to meet a wide variety of blood cell separation needs. The role of the apheresis system is to control the behavior, separation, and collection of blood components from the bowl while maintaining maximum donor safety. The system controls the flow rates of blood and components through variable pump speeds. It directs the flow of components out of the bowl, by fully automatic opening and closing of valves based on the output of the system sensors. The system monitors the separation of blood components in the bowl by an optics system that aims at the shoulder of the bowl. A sensor on the effluent line monitors the flow of components out of the bowl. 

The majority of functional assays involve primary signaling. In the case of GPCRs, this involves activation of G-proteins. However, receptors have other behaviors— some of which can be monitored to detect ligand activity. For example, upon stimulation many receptors are desensitized through phosphorylation and subsequently taken into the cell and either recycled back to the cell surface or digested. This process can be monitored by observing ligand-mediated receptor internalization. For... 

The simulated short-circuit test was developed to characterize the response of the separator to a short circuit without the complications of battery electrodes. The separator was spirally wound between lithium foils and placed in an AA-size can. To avoid lithium dendrite formation, an alternating voltage was applied to the cell. The cell current and can temperature were monitored. Figure 6 shows the behavior of Celgard membranes. 

OS 59] [R 34] [P 42] The furan and dimethoxylated product concentrations were monitored as a function of the cell voltage [71]. The product concentration follows the sigmoidal shape of the bromide oxidation current. The furan concentration shows the inverse behavior. For a cell voltage of 3 V and a current of 30 mA, a concentration of 50% is approached. The product formation is limited by mass transfer of bromine generation. 

When cells are suspended in a biological fluid or culture medium, both serum proteins and cells interact with the surface substrate. Serum protein adsorption behavior on SAMs has been examined with various analytical methods, including SPR [58-61], ellipsometry [13, 62, 63], and quartz QCM [64—66]. These methods allow in situ, highly sensitive detection of protein adsorption without any fluorescence or radioisotope labeling. SPR and QCM are compatible with SAMs that comprise alkanethiols. In our laboratory, we employed SPR to monitor protein adsorption on SAMs. 

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