Membranes biological, imaging

The electrochemical systems studied by the fluorescence method are based upon the adsorption of lipid-hke compounds similar to the molecules that make up the cell membrane. The vast literature of methods and a variety of fluoro-phores are available for our use in the study of electrochemical systems. A brief review of the use of fluorescence microscopy in the study of biological systems is presented, because a number of the probes used for staining the biological structures are relevant for the electrochemical work presented. Moreover, the methods used in biological imaging to encourage fluorescence and to improve contrast are relevant for the work on electrode surfaces. 

Biological Applications Measuring membrane potential imaging exocytosis at fertilization ... 

Koryta et al. [48] first stressed the relevance of adsorbed phospholipid monolayers at the ITIES for clarification of biological membrane phenomena. Girault and Schiffrin [49] first attempted to characterize quantitatively the monolayers of phosphatidylcholine and phos-phatidylethanolamine at the ideally polarized water-1,2-dichloroethane interface with electrocapillary measurements. The results obtained indicate the importance of the surface pH in the ionization of the amino group of phosphatidylethanolamine. Kakiuchi et al. [50] used the video-image method to study the conditions for obtaining electrocapillary curves of the dilauroylphosphatidylcholine monolayer formed on the ideally polarized water-nitrobenzene interface. This phospholipid was found to lower markedly the surface tension by forming a stable monolayer when the interface was polarized so that the aqueous phase had a negative potential with respect to the nitrobenzene phase [50,51] (cf. Fig. 5). 

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. 

The last sample preparation method for IMS is the transfer of a tissue section onto the PVDF membrane. Proteins in the section can be transferred onto the PVDF membrane and then analyzed on the membrane. The advantage of this method is that the enzyme can be digested for MS" measurement, because the information on protein localization in the organization is fixed on the membrane.5,20 This technique can denature, reduce, and digest the proteins in the tissue section efficiently and remove the salt from the tissue. This increases the efficiency with which biological molecules are ionized, making it possible to obtain sensitive mass imaging spectra. 

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