Cell membranes, imaging

Trimethylaminodiphenylhexatriene chloride (TMADPH Fig. 7.45) is a fluorescent quaternary ammonium molecule that appears to permeate cell membranes [595]. TMADPH fluoresces only when it is in the bilayer, and not when it is dissolved in water. Therefore, its location in cells can be readily followed with an imaging fluorescence microscope. One second after TMADPH is added to the extracellular solution bathing HeLa cell types, the charged molecule fully equilibrates between the external buffer and the extracellular (outer) leaflet bilayer. Washing the cells for one minute removes >95% of the TMADPH from the outer leaflet. If the cells are equilibrated with TMADPH for 10 min at 37°C, followed by a one-minute wash that removed the TMADPH from the outer leaflet, the fluorescent molecule is... 

Dialkylanthracene-containing squaraine dyes 17 show intense absorption and emission in the NIR region (720-810 nm) [74]. They are compatible with aqueous environments and show substantial enhancement of quantum yields and fluorescence lifetimes in hydrophobic and micellar media, suggesting that these dyes can be potentially useful as fluorescent probes in biological applications, e.g., for imaging of hydrophobic domains such as cell membranes. 

Benninger, R. K. P., Onfelt, B., Neil, M. A. A., Davis, D. M. and French, P. M. W. (2005b). Fluorescence imaging of two-photon linear dichroism Cholesterol depletion disrupts molecular orientation in cell membranes. Biophys. J. 88, 609-22. 

Figure 13.9 represents the TEM image of LDH particles and their cellular internalization. As expected, LDH particles are internalized by endocytosis. Figure 13.9(A) shows the cellular uptake process of LDHs after 3h of treatment, and demonstrates a successive entry of LDH by endocytosis first the LDH particles were located around the cell membrane due to their positive charge ( ), then they migrate to the membrane ruffles which are considered as endocytic bodies ( ), finally the coated intracellular vesicles were formed as early endosomes ( ). Figure 13.9(B)...

Fig. 1 Real-time tracking of cell adhesion [42]. (a) Components of a total internal reflection fluorescent microscope (TIRFM). (b) The cell adhesion process (7) a cell approaches the surface, (2) the cell lands, (3) the cell attaches, and (4) the cell spreads out on the surface. The evanescent field was generated by total internal reflection of a laser beam at the glass-water interface. Cells with fluorescently labeled membranes (dashed lines) were plated on SAMs. Cell membranes within the evanescent field (solid line) were observed by TIRFM. Corresponding TIRFM images are shown below...

We assembled a TIRFM with low magnification to study cell adhesion behavior on SAMs with various functional groups [42]. Figure lb shows a schematic illustration of the cell adhesion process and the corresponding TIRFM images. A suspension of cells with fluorescently labeled cell membranes is applied onto a substrate (Fig. lb-1). At first, no bright spots were observed by TIRFM,... 

Fig. 17. Confocal fluorescence imaging of [Zn(ATSM)] in IGROV cells (100 pM, where Q1 — Q2 = Me, M = Zn(II), R1 = R3 = H and R2 = R4 = Me, /ex = 488 nm, DMEM with 1% DMSO). Brightfield image shows formation of needle-like crystalline material on the cell plate (N.B. Small crystallites may be endocytosed by the cells rather than passively diffuse through the cell membrane).

Fig. 18. (a) Representation of the tumor hypoxic state (diagram adapted from Ref. (83a). Arrow direction indicates decrease in pC>2 (< 1 mmHg), achieved for tumor depths larger than 100 pm (b) proposed mechanism for redox-mediated retention of [Cu(ATSM)] in hypoxic cells (101-105). Note Contrary to common belief cell membrane crossing solely by direct diffusion is unlikely for compounds of this family is unlikely, as indicated by fluorescence imaging work on aromatic Zn(II) analogs (vide infra). Endocytosis is the more likely uptake mechanism (112-113). 

Fig. 2.2-1. A neutron capture event seen in relation to the size of the target. Electron microscopic image of uncontrasted tumor tissue, stained for boron by antibodies. The smaller structure surrounded by clusters of dots is the nucleus. The thin structure lined with dots is the cell membrane. The dots are gold particles attached to the antibodies which are specifically directed against the...

Fig. 11.2 (a) HAADF-STEM image of a stained cell section (40nm thick). A SWNT cluster within a lysosome invading the lysosomal cell membrane, (b) Corresponding high-resolution lattice image of SWNTs at the lysosomal membrane from boxed area. Cytoplasm (cy) and secondary... 

Nuclear imaging techniques, like single photon emission tomography (SPECT) and positron emission tomography (PET), directly assess myocardial perfusion, cell membrane integrity, cellular metabolism, and the molecular mechanisms of ischemic viable or necrotic myocardium, thereby indicating revascularization procedures or not. 

Non-contracting viable myocardium traps potassium analogues in the myocyte potassium space, such as Thallium ( ° T1) for SPECT imaging and Rb for PET imaging, reflecting sufficient cell membrane... 

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