Controlled Delivery Microcapsules

Companies involved currently in microencapsulation technology are listed in Table 7.5, the large majority of which are active outside the textile industry. 

Much effort has been made to adapt microcapsules to textiles, with microcapsules containing perfumes, cosmetic products (moisturizers, fresheners, toners, etc.), bactericides, acaricides or even a combination of ingredients (e.g., a perfume 

Sederma Sekisui Sipcam South West Research Inst. 

Most commercially available microcapsules are sized between one and several hundred micrometers (typically, microcapsules are 20-50 pm in diameter) and a concentration of 20 to 45% (by weight). 

Fragances apple, alpinair, banana, bergamot, blackcurrant, bubblegum. 

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Singh, M., A. Singh, G.P. Talwar, Controlled Delivery of Diphtheria Toxoid Using Biodegradable Poly(D, L-Lactide) Microcapsules, Pharmaceutical Research. 8, 958, 1991. 

Membrane-reservoir systems based on solution-diffusion mechanism have been utilized in different forms for the controlled delivery of therapeutic agents. These systems including membrane devices, microcapsules, liposomes, and hollow fibres have been applied to a number of areas ranging from birth control, transdermal delivery, to cancer therapy. Various polymeric materials including silicone rubber, ethylene vinylacetate copolymers, polyurethanes, and hydrogels have been employed in the fabrication of such membrane-reservoir systems (13). 

Singh, M., Sin, A., and Talwar, G. P., 1991a, Controlled delivery of diphtheria toxoid itsing biodegradable poly(D,L -lactide) microcapsules, Pharm. Res. 8 958-961. 

It is important to point out that the presence of the fulfilled encapsulation technology inside the nano- and microcontainers does not lead to their wide application. First of all using microcapsules requires also to guarantee their controllable delivery and release of capsulated substances. Also, it is desirable to provide us with remote delivery and release. Remote control over capsules permeability can be realized in several ways using microwave radiation, laser irradiation or ultrasound. 

The problems of bio-functional polymers were diseussed on the 4 session. This session included 6 lectures. The speakers gave information about biofunctional dendritic architectures, biocompatible and bioactive polymers containing saccharide fimctionality, design and mechanisms of antimicrobial polymers, control of protein adsorption on functionalized electrospun fibers, microcapsules and nanoparticles for controlled delivery and repair, smart nanocarriers for bioseparation and responsive drug delivery systems. 

M. Singh, A. Singh and G.P. Talwar, "Controlled delivery of diphtheria toxoid using biodegradable poly(D,L-lactide) microcapsules", Pharm. Res., 8,958-961,1991. 

W. E., Long-acting delivery systems for polypeptides. Inhibition of rat prostate tumors by controlled release of [D-Trp ]-LHRH from injectable microcapsules, Proc. Natl. Acad. Sci. 

Makino K, Mack EJ, Okano T, Kim SW. A microcapsule self-regulating delivery system for insulin. J Controlled Release 1990 12 235-239. 

In the dual liposome-microcapsule system, two factors control the release of the active substance escape from lipsomes into the microcapsule interior, and diffusion across a rate limiting capsule wall into the external environment. This system can take advantage of the inherent instability of some lipsomes while over-coming many of the problems associated with their use by protecting them from the environment by the capsule. At the same time, a new measure of control over the time at which a microcapsule will commence delivery of the enclosed agent is introduced by careful choice of the liposome composition. By changing the nature of the liposomes or of the encapsulant (e.g. alginate) different release times and patterns can be obtained. 

Hu S-H, Tsai C-H, Liao C-F et al (2008) Controlled rupture of magnetic polyelectrolyte microcapsules for drug delivery. Langmuir 24 11811-11818... 

Mathiowitz [35 0] realizes reservoir-type delivery systems recurring to a photochemical control. Microcapsules, built up by interfacial polymerization of polyamide, also contain azobisisobutyronitrile, a substance that emanates nitrogen due to a photochemical action. Accordingly, after exposition to light, microcapsules internal pressure increases (as a result of nitrogen release) until membrane rupture and consequent contents release. 

Polyelectrolyte complexes can be used as implants for medical use, as microcapsules, or for binding of pharmaceutical products, including proteins. In recent years, a new class of organometallic polymers, polyphosphazenes, has become available. Synthetic flexibility of polyphosphazenes makes them a suitable material for controlled-release technologies. Desirable characteristics of a polymeric system used for drug delivery are as follows ... 

Figure 1 Formulation of controlled drug delivery systems using the supercritical fluid-derived RESS process (A) films, (B) microparticles/nanoparticles/ liposomes, (C) coated products including microcapsules, and (D) microporous foams.

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