Molecules entrapment

Concerning the mechanism of action of catechins, studies carried out on S. aureus and E. coli cells by Ikigai et al. [72] reported that their bactericidal effect is primarily involved in the damage of bacterial membranes catechins induce a rapid leakage of small molecules entrapped in the intraliposomal space, determining the aggregation of the liposomes. These actions cause damage in the membrane lipid bilayer and cell death (Table 1). 

Construction of the optode for optical biosensor requires immobilization of sensitive compounds in the host matrix. There are several methods enabling molecules entrapment. One can use gels, polymers, saccharose, various meshes and membranes78. In case of fiberoptic indirect sensors optode must be attached to the fiber tip. Nowadays, there are two commonly used optode host materials sol-gel materials and polymers. 

The small molecules entrapped in the H-ZSM-5 zeolite channels because of coke deposition which occured at the outer surface of the particles, have been examined by CP/MAS- C-NMR spectroscopy (10). Figure 3 shows that isoparaffins are more abundant than linear chains, which agrees with other classical data on methanol conversion (47,48). 

N. Jager-Lezer, I. Terrisse, E. Bruneau, S. Tokgoz, L. Eerreira, D. Clausse, M. SeiUer,d and J.L. Grossiord Influence of Lipophihc Surfactant on the Release Kinetics of Water-Soluble Molecules Entrapped in a W/O/W Multiple Emulsion. J. Controlled Release 45, 1 (1997). 

Clathrasils are host/guest complexes comprised of covalent guest molecules entrapped within cages formed by a silica host framework (1, 2). Like all zeolitic materials, clathrasils have enormous potential as advanced optical and electronic materials whose composite character permits synthetic manipulation of both the molecular structure of the guest species and the extended structure of the host framework (3, 4). Like other zeolites, however, clathrasils also suffer severe handicaps as advanced materials due to a reluctance to form large single crystals and a tendency to form stoichiometrically and structurally defective crystals (5 -10). 

Similar to hydrophilic flavonoids, hydrophobic flavonoids can affect membrane permeability. Alterations in this biophysical property of liposome bilayers lead to the release of bulky molecules entrapped into the inner aqueous space. As mentioned in the previous section, a strong correlation was found between flavonoid retention to a hydrophobic matrix and their capacity to induce membrane leakage [Ollila et al., 2002]. Interestingly, hydrophilic flavonoids, such as (—)-epicatechin and related procyanidins (dimer to hex-amer) prevented Fe2 + -mediated liposome permeabilization, although in this case the beneficial effect could be related to both their antioxidant and metal chelating capacities and their membrane stabilizing properties [Verstraeten et al., 2004],... 

When the partition dynamics are rapid, the solute distribution in vesicles will obey the same laws as the distributions in micelles. However, when the transmembrane diffusion time of molecules entrapped within the aqueous vesicle core or incorporated into the hydrocarbon phases exceeds the characteristic time of their chemical transformation in chemical reactions, then their partitioning is set by their initial statistical distribution rather than their migration dynamics. In this case also, a Poisson law is appropriate to approximate their distribution among vesicles. This follows because the volume of the inner aqueous phase generally exceeds 10 A, and the maximiun number of molecules that can be entrapped inside the vesicle is correspondingly large. 

Boxing effect due to electronic confinement for the guest molecule entrapped into the zeolite framework (Zicovich-Wilson et al., 1997)... 

Another very important conclusion that emerged from these studies (where microcrystalline cellulose was used as powdered substrate) was that molecular oxygen did not quench the triplet state of molecules entrapped within the polymer chains of this natural polymer. All these studies could be done with air equilibrated samples, and nitrogen or argon purged samples provide similar results for the efficiencies of the quenching process, within experimental error. This property of cellulose makes it a very special substrate to be used for room temperature fluorescence and phosphorescence studies. 

As pointed out in Sec. II the echo attenuation curve for the PFG experiment, when applied to molecules entrapped in an emulsion droplet, is a signature of the size of the emulsion droplet, is a signatiue of the size of the emulsion droplet (cf Fig. 2). As a conse quence, droplet sizes can be determined by means of the PFG experiment. 

Poly(ethylene glycol) bisamine-rofaxa-a-cyclodextrin PEG end capped with 2,4-dinitrofluorobenzene after complexation in aqueous solution 20-23 alpha-CD molecules entrapped on each chain rotaxane is insoluble in water hydrogen bonds between entrapped alpha-CD s suggest alternating face-to-face, back-to-back arrangement of the CD s. [229,230]... 

In the case of DNA added to a micellar solution of polycation, the micelles can stay stable in some cases (it depends on the hydrophobicity of the micellar core and strength of the electrostatic interactions). This can be proven if pyrene or other hydrophobic molecules entrapped in the hydrophobic interior are not released even after addition of DNA [77]. It has to be noted that micelles are in thermodynamic equilibrium with unimers and that both species can form electrostatic interactions with DNA. When the micelles do not undergo a strucmral change, no rearrangement into a scrambled eggs structure takes place between the amphiphilic polycation and DNA, and because DNA is in minority, it adds to the positive shell of the structure until neutralization (Scheme 11, case 2). 

Kulikov OV, Rath NP, Zhou D, Carasel lA, Gokel GW. Guest molecule entrapment by both capsule and hydrocarbon sidechains in self-assembled pyrogallol[4]arenes. New J Chem 2009 33 1563-9. 

Micellar aggregate of amphiphilic molecules entrapping a polar solubili-... 

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