Carriers Microparticles

As for animal cell entrapment in hydrogel microparticles or microcapsules, encapsulation procedure should proceed under physiological conditions within a short time (20-30 min), in order to provide cell viability, and to be as simple as possible because all manipulations are carried out under strictly sterile conditions. Taking into account all these requirements, it should be noted that the list of polymer materials and methods for animal cell encapsulation is rather limited. So-called alginate-based carriers (microparticles, micro- and nanocapsules) assure the favorable polymer systems for animal cell immobilization. 

Polymeric microparticles have been studied and developed for several years. Their contribution in the pharmacy field is of utmost importance in order to improve the efficiency of oral delivery of drugs. As drug carriers, polymer-based microparticles may avoid the early degradation of active molecules in undesirable sites of the gastrointestinal tract, mask unpleasant taste of drugs, reduce doses and side effects and improve bioavailability. Also, they allow the production of site-specific drug targeting, which consists of a suitable approach for the delivery of active molecules into desired tissues or cells in order to increase their efficiency. 

The aim of this chapter is to summarize some of the research findings on xylan, a natural polymer extracted from corn cobs, which presents a promising application in the development of colon-specific drug carriers. Physicochemical characterization of the polymer regarding particle size and morphology, composition, rheology, thermal behavior, and crystallinity will be provided. Additionally, research data on its extraction and the development of microparticles based on xylan and prepared by different methods will also be presented and discussed. 

Deehee, D., Meekle, H. P., Walter, E., Evaluation of cationic solid lipid microparticles as synthetic carriers for the targeted delivery of macromolecules to phagocytic antigen-presenting cells. Biomaterials 23 (2002) 4667-4676. 

Arthursson P, Edman P, Laakso T, Sjoholm I (1984) Characterization of polyacryl starch microparticles suitable as carrier for proteins and drugs. J Pharm Sci 73 1507-1513. 

The formed microparticles of Si C will move into the hot chamber or the sublimation zone with the aid of the inert helium carrier gas. Once in the sublimation zone, the microparticles will sublime to form Si, Si C, and SiQ, as in the case of seeded sublimation growth. A thermal gradient is applied, as illustrated in Figure 1.9, so that the sublimed species will condense on the seed, as in the case of seeded sublimation growth. 

Livesay s patent (Ref 4) claims that expls and small arms propints can be codified for post-use identification by incorporation of microparticles of (unspecified) Sr oxides or salts of 0.1 wt % into recoverable fireproof carrier particles of a unique characteristic size (1—250 microns) and shape so that the total (micro plus carrier) particle has a d of > 3g/cc and an incineration temp of 400—500°... 

For some applications, it is important to use protein particles of a specific size. When drugs are released within the body there is an initial boost followed by an exponential decay in the concentration over time. Sometimes it is desirable or necessary to minimize the variation of concentration within patients and one of the ways to accomplish this is by using microparticles distributed within a polymer carrier. Tom et al. (1993) used... 

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