Single cell trapping

Figure 13. Image showing the dynamic array cytometer consisting of single cell traps (Voldman et al. [78]).

Chen NC et al (2014) Single-cell trapping and impedance measurement utilizing dielectrophoresis in a parallel-plate microfluidic device. Sens Actuator B 190 570-577... 

In fact, this approach has been applied to image single cells trapped in droplets of Dulbecco s phosphate-buffered saline (DPBS) in oil with the potential to extend the methodology to study single cell dynamics as discussed in Section 9.3.5.2. 

Ashkin, A. Dziedzic, J. M. Yamane, T., Optical trapping and manipulation of single cells using infrared laser beams, Nature 1987, 330, 769 771... 

A clever way to minimize the unwanted background from the cover plate or the environment is combining laser tweezers and confocal Raman spectroscopy (LTRS) [73, 74], While the single cells are levitated well off the surface and held in the focus of the laser beam the Raman spectral patterns of these cells are recorded with high sensitivity. Another appealing fact is the usage of one laser for both Raman excitation and optical trapping to keep the instrumental efforts as low as possible. Additionally the trapped cells can also be micro-manipulated and moved from one place to another, e.g., from the native matrix to a clean collection chamber. 

Single Cell FTMS instrument design which uses one trapped ion... 

Shelby, J.P., Mutch, S.A., Chiu, D.T., Direct manipulation and observation of the rotational motion of single optically trapped microparticles and biological cells... 

Fig. 14. Geometry of a single cell of a penning gauge. Space charge of the trapped, circulating electrons equalizes the axis potential with that of the cathode. Thus, the electric field is radial. Electron density is at a maximum a short distance from the anode. Electrons progress radially toward the anode only as they lose kinetic energy, mainly through inelastic (ionizing) collisions with molecules (40).

Figure 12 Combination of dielectrophoretic field cage (DFC) and optical tweezers (OT) for the measurement of bead-cell adhesion (A) 4.1-(xm polystyrene particle trapped with laser tweezers (right) in contact with T-lymphoma cell ( — 1 5 pm in diameter). Cell and bead were brought into contact. The time for stable adhesion was measured. (B) Schematic representation of the experimental system used to measure the adhesion forces between bead and cell with the cell trapped in a DFC and the bead trapped in the laser focus of the OT. (C) Probing different surface regions of the cell for bead-cell adhesion (five beads are attached to a single cell). (Reprinted from Ref. 91 with permission.)...

Figure 11. (A) Scheme of the PDMS microfluidic device. Inset channel crossing with the cell trap composed of microstmctured obstacles, (B) Scanning electron micrograph of the cell trap, (C) single cell in a channel navigated by optical tweezers in the microchannel, (D-G) optical micrographs of a single cell at the injection position during SDS lysis. SDS flow is from channel 4 through the cell trap into channel 2.

Jess PRT et al (2006) Dual beam fibre trap for Raman microspectroscopy of single cells. Opt Express 14(12) 5779-5791... 

Ramser K et al (2004) A microfluidic system enabling Raman measurements of the oxygenation cycle in single optically trapped red blod cells. Lab Chip 5 431 36... 

Xie C, Dinno MA, Li Y (2002) Near-infrared Raman spectroscopy of single optically trapped biological cells. Opt Lett 27(4) 249-251... 

Zheng F, Qin YJ, Chen K (2007) Sensitivity map of laser tweezers Raman spectroscopy for single-cell analysis of colorectal cancer. J Biomed Opt 12(3) 034002 Chan JW et al (2008) Nondestmctive identification of iudividual leukemia cells by laser trapping Raman spectroscopy. Anal Chem 80(6) 2180-2187... 

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