Magnetic capsule

Ishikawa, K., Ohishi, M., Saitho, T., Abe, M., and Tamura, Y., New magnetic capsule toner and carrier with high imaging-quality and low fusing temperature prepared by ferrite plating, in Abstracts of 6th International Conference on Ferrites, 87, Tokyo, EB-04 (1987). 

The foregoing results demonstrate that the thickness of the capsule wall can be controlled at the nanometer level by varying the number of deposition cycles, while the shell size and shape are predetermined by the dimensions of the templating colloid employed. This approach has recently been used to produce hollow iron oxide, magnetic, and heterocomposite capsules [108], The fabrication of these and related capsules is expected to open up new areas of applications, particularly since the technology of self-assembly and colloidal templating allows unprecedented control over the geometry, size, diameter, wall thickness, and composition of the hollow capsules. This provides a means to tailor then-properties to meet the criteria of certain applications. 

Haeiwa, T., Segawa, K. and Konishi, K. (2007) Magnetic properties of isolated Co nanopartides in Si02 capsule prepared with reversed micelle. Journal of Magnetism and Magnetic Materials,... 

D., Trahms, L., High-resolution monitoring of the gastrointestinal transit of a magnetically marked capsule, J. Pharm. Sci. 1997, 86, S1218-S1222. 

W., Magnetic marker monitoring of esophageal, gastric and duodenal transit of non-disintegrating capsules, Pharmazie 1999, 54, 426-430. 

BraynerCoradin, T., Fievet-Vincent, F., Livage, J. and Fievet, F. (2005) Algal polysaccharide capsule-templated growth of magnetic nanoparticles. New Journal of Chemistry, 29,... 

The kinetic information for NMR experiments is contained in the line broadening observed for a nucleus that resides in two different magnetic environments, and values for rate constants can be obtained using line-shape analysis.28,68,69 Line broadening experiments obtained using ID NMR is the method of choice when analyzing the kinetics of a molecule in two sites. 2D NMR techniques, such as 2D EXYS are employed when the kinetics are sequential, i.e. more than one step, or multiple sites are analyzed.69 For example in the case of supramolecular systems this technique was employed to measure the exchange kinetics in capsules.70... 

Figure 2 Magnetic resonance image showing the semisolid fraction of a sandwich-based meal lying in the stomach. A small capsule given soon after the meal floats on the liquid above the solid mass, becoming stuck in the gastric rugae in the body of the stomach or floats off ahead of the bulk of the gastric contents.

A nuclear magnetic resonance method for chlorpromazine has been reported [178]. For tablets, capsules, and bulk chemical, the sample is shaken with CHCI3 containing cyclohexane or piperanol as an internal standard. For injectable solutions, tetramethylammonium bromide was used as the internal standard. The NMR spectrum was recorded between 0 and 7.0 ppm, and the drug resonance at 2.7 ppm (relative to TMS) measured. The signals for the respective internal standards were at 1.5, 6.0, and 3.3 ppm. 

More easily to be understood are the effects observed when ir electrons are present in the adsorbed molecule. Figure 28 shows the change of the photoelectric emission of a platinum surface covered with benzene (76). The benzene was contained in a capsule, which could be smashed magnetically (see F in Fig. 2). The tube, G in Fig. 2, was cooled by liquid air. At the points of the curve marked with arrows, the cooling of G was interrupted for 1 or 2 min., so that a small quantity of benzene molecules might be adsorbed at the platinum surface. The sensitivity increased (Fig. 28) at first and then decreased after passing a maximum, which was reached in the vicinity of the monomolecular covering (B, C in Fig. 28). 

Method. The tablet or capsule containing ephedrine is pulverized and mixed with 70 ml of ethanol at 40 °C for 20 min with magnetic stirring. The resulting solution is filtered and the clear filtrate is diluted to 100 ml. 1 ml of this solution is treated with 5 ml of ethanol, 5 ml of acetone, 1 -2 ml of a solution of DNS-C1 (2 mg/ml in acetone) and 2 ml of a solution of sodium bicarbonate (10 mg/ml in water). The solutions are shaken and placed in the dark for 1 h. An aliquot portion of the resulting mixture is analyzed by TLC on plates of silica gel using benzene-ethanol-acetic acid (90 10 1) as solvent. An alternative procedure for ephedrine has been discussed earlier [123]. 

Multiple guests have further been used as kinetic templates for creating multicapsules with one guest per chamber (Fig. 13).92 The dynamic characteristics and the overall potential of such intriguing carceplexes have not been fully examined though there was some indication that (a) encapsulation of three molecules of methyl acetate inside 23 was cooperative and (b) encapsulated pyrazines would in 24 modulate each other s magnetic environment.92,94 It is also worth mentioning that from the synthetic standpoint the preparation of capsule 25 was accomplished in an excellent 30% yield.94... 

The capsules with a defined shell (so-called hollow multilayered polyelectrolyte capsules) are free-standing LbL films with a peculiar advantage - the ability to uptake the material inside the capsule, in other words to encapsulate it and to control its release by changing the LbL film permeability properties. Macromolecules like proteins have been successfully loaded into polyelectrolyte LbL capsules through pH-controlled and water/ethanol mixture-controlled methods [118, 119], Alternative stimuli could be applied, e.g., a magnetic field [120], This approach consists of destabilization of the LbL membrane, which then becomes more permeable. The capsule is loaded with molecules of interest under destabilized conditions and then the conditions are changed back to the initial ones (under which the LbL shell is stable). 

The fate of nanoparticles has also been investigated in vivo. Albrecht et al. studied the in vivo mucoadhesive properties of thiomer formulations using magnetic resonance imaging and fluorescence detection (Albrecht et al. 2006). Following the hypothesis that unhydrated thiomers provide better mucoadhesion in vivo the group developed polycarbophil-cysteine microparticles loaded with fluoresceine diacetate (FDA) in Eutex capsules to maintain them in the dry... 

Fig. 4 (Top) The walls of the capsule are twisted and create an asymmetric magnetic environment. (Bottom) Calculated complex with 1 -hexadecyne...

Mansour et al. [46] developed a simple, rapid efficient quantitative proton magnetic resonance method for the determination of mefenamic acid in Ponstan capsules. The method is based on a comparison between the sum integrals of the two methyl singlets of mefenamic acid and that integral of the sharp singlet of / -methoxybenzylidenemalononitrile (internal standard). The method gave accurate and reproducible results. 

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