Vesicles , metallization

Figure 6-10. a) Surfactant oil in water micelles, b) water-in-oil reverse mieelles, and c) vesicles. Metal colloids can be generated in the intraparticle space. 

Blase,/, bubble, bleb blister, vesicle cavity (Metal.) blowhole bladder bladder-shaped vessel, as the body of a retort or still still. Blaae-. blowing, blast, -apparat, m. still blast apparatus, -balg, m. bellows, -lampe, /. blast lamp. 

It proves possible to anchor catalysts of H2 evolution to the outer and inner surface of the vesicle membrane. These catalysts are finely dispersed (10-20 A in diameter) metal Pt or Pd particles formed via reduction of appropriate salts in vesicle suspension (see [15, 16] and refs, therein). Among the viologen-type electron carriers a promising one is p-bis (1,2,5-triphenyl-4-pyridil)benzene which possesses reduction potential low enough for water reduction at neutral pH. Recently, using this mediator we succeeded in H2 evolution conjugated with PET... 

Templates made of surfactants are very effective in order to control the size, shape, and polydispersity of nanosized metal particles. Surfactant micelles may enclose metal ions to form amphiphilic microreactors (Figure 11a). Water-in-oil reverse micelles (Figure 11b) or larger vesicles may function in similar ways. On the addition of reducing agents such as hydrazine nanosized metal particles are formed. The size and the shape of the products are pre-imprinted by the constrained environment in which they are grown. 

Probes based on macrocyclic amines include dansylamidoethylcyclen, which can detect zinc at sub-nanomolar concentrations and probes containing xanthene as the chromophore with an ideal wavelength range for intracellular studies.953,962 It is also important that the sensors can differentiate between the alkali metals, which are present at higher concentrations, and zinc. 2, 7-dichlorofluorescein-based sensors have been used in biological systems and reveal concentrations up to ca. 0.3 mM in hippocampal nerve synaptic vesicles.963... 

Another feature of mitochondria is that they handle the syntheses of both iron/sulfur and iron haem units. It appears as if handling metal ions, including that of iron, is risky in the cytoplasm. In fact, other metal ions are pumped out of cells or into vesicles and in some cases into mitochondria - especially calcium. 

Fig. 7.5. A schematic indication of some of the different membrane separated compartments in an advanced cell. PEROX is a peroxisome MITOCHLORO is either a mitochondrion or a chloroplast CHROMO is a vesicle of, say, the chromaffin granule ENDO is a reticulum, e.g. the endoplasmic reticulum. Other compartments are lysosomes, vacuoles, calcisomes and so on. Localised metal concentrations are shown. The figure is of a transverse section. To appreciate a cell fully it is necessary to have serial plane sections in parallel along the. "-direction.

Khramov, M.I. and Parmon, V.N. (1993) Synthesis of ultrafine particles of transition-metal sulfides in the cavities of lipid vesicles and the light-stimulated transmembrane electron-transfer catalyzed by these particles. Journal of Photochemistry and Photobiology A-Chemistry, 71, 279-284. 

Add at least 5 mg/ml of a sulfhydryl-containing protein or other molecule to the SPDP-modified vesicles to effect the conjugation reaction. Molecules lacking available sulf-hydryl groups may be modified to contain them by a number of methods (Chapter 1, Section 4.1). The conjugation reaction should be done in the presence of at least lOmM EDTA to prevent metal-catalyzed sulfhydryl oxidation. 

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