PubMed · 15411414
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E ZEUTHEN. 1950. Cartesian diver respirometer.. https://doi.org/10.2307/1538575
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We present a systematic numerical analysis of the thermal properties of dielectrophoretic single-cell traps. The influence of the thermal conductivity of the wall material is investigated, as well as the influence of the electrical conductivity of the liquid and the applied potential. We also explore the effect of the electrode geometry on the thermal properties of the trap. We show that substrates with thermal conductivities smaller than 100 W/mK can affect significantly the temperature increase inside the traps. Our results also show, for the first time, that for flat electrodes there is an optimum electrode to trap surface area ratio for which the ratio of temperature increase in the liquid to dielectrophoretic force on a particle can be minimized. This result will be useful in the future development of optimized dielectrophoretic traps.
BACKGROUND AND OBJECTIVES: Laser-activated micro- and nano-bubbles (LAB) in cells may be used as universal and sensitive non-toxic probes for measuring functional properties of individual cells. STUDY DESIGN/MATERIALS AND METHODS: Such bubbles can be detected and imaged by microscopy and flow cytometry. LABs in living blood and tumor cells were induced by pulsed (532 nm, 10 nanoseconds) laser radiation and detected by the thermal lens optical method. RESULTS: Registered lifetime and maximal diameter of the studied LABs varied within the ranges of 0.02-10 microseconds and 0.44-100 microm, respectively. LAB parameters, thresholds and probabilities, were found to depend upon the physiological state of cells. Specificity and sensitivity of LAB cytometry were increased due to the use of light-absorbing nanoparticles conjugated to specific monoclonal antibodies. CONCLUSIONS: LAB were found to be the universal phenomena that can be used for sensitive and non-invasive monitoring of any individual cell, intact or nanoparticle-treated.
The interaction between living matter and optical spectra (Raman, infrared, fluorescence spectroscopy) can be used to characterize simple or complex biomolecular systems. At the cell and tissue level, these microspectroscopic techniques can be used to construct descriptors of molecular or supramolecular (nucleic acids, proteins, lipids, etc.) function in a given biological situation (healthy or pathological tissue, normal or pathological cell, induction of cytotoxicity, apoptosis or differentiation, presence or not of a resistance phenotype, etc.) At the present time vibrational spectroscopy appears to be a particularly powerful technique for characterization of the early phases of pathological processes occurring within given cells or tissues. It could be used to develop tools for early diagnosis and prediction of therapeutic response.