Biological microencapsulation

Price, R., Gaber, B. and Lvov, Y. (2001) In-vitro release characteristics of tetracycline, khellin and nicotinamide adenine dinudeotide from halloysite a cylindrical mineral for delivery of biologically active agents. Journal of Microencapsulation, 18, 713—723. 

Photodegradation. Schaefer and Dupras (39) reported that emulsifiable formulations of methoprene at 0.1 ppm in water showed a rapid photodissipation in sunlight, whereas the commercial, microencapsulated formulation remained biologically active in water for several days under similar conditions. Aqueous solutions of methoprene undergo very rapid (t, <1 hr) photoequilibration to a mixture (,ui l) of 2E, 4E 2Z, 4E isomers (26, 39). 

One particular example of controlled release is sustained release. In this form the desired material is continuously released over a period of time at a constant rate. Two timely publications (3)(4) cover the general area of controlled release, which can also include the controlled release of agricultural materials and biological materials, far example, pheromones. In using the term microencapsulation in this article, the author intends to refer to capsules in the size range of 1 micron to 1000 microns. Capsules below 1 micron in size are frequently referred to as nanocapsules and they are made by one or more very specialized methods (5). The term capsule refers to macro objects in the order of 1 millimeter or larger. This term of capsule is frequently used in the delivery of pharmaceuticals. 

Physical methods that involve the supporting of a biological element in any way that is not depending on covalent bond formation (e.g., adsorption, entrapment, microencapsulation). These procedures are simple and in most cases the biocatalyst remains unchanged. 

Interactions between protein and polysaccharide have attracted increasing interests in the past two decades also because of their implications in many biological processes such as the organization of living cells and the use in many industrial applications such as microencapsulation, protein separation and purification, and in processed foods (Berdick and Morawetz 1954 Burgess and Carless 1984 Dubin et al. 1994 Tolstoguzov 1991). 

Examples of formulations which may be candidates for waivers based on particle size include microencapsulated formulations which are not biologically available for inhalation during mixing/loading or application, granular products placed in or on the soil, and baits applied by hand. 

Following intramuscular (IM) administration, drugs must cross one or more biological membranes in order to enter the systemic circulation. Intramuscular injection is used mainly for drugs and vaccines that are not absorbed orally, for example, aminoglycosides, insulin, and hepatitis vaccine. The IM route is often used for sustained medication and specialized vehicles, such as aqueous suspensions, oily vehicles, complexes and microencapsulation, which has been developed for slow delivery of drugs by this route. ... 

Groenwald BE, Pereiro F, Purnell TJ and Scher HB Microencapsulated thiocarbamate herbicides a review of their physical, chemical and biological properties, Proceedings, British Crop Protection Conference - Weeds, pp. 185-191 (1980). 

Various methods have been proposed for whole cell Immobilization Including adsorption and covalent attachment to a preformed carrier, crosslinking, flocculation, microencapsulation, and entrapment. Physical entrapment In a porous matrix Is by far the most flexible and most commonly used technique. Considering the fact that the polymer network has to be formed In the presence of the finally entrapped biological material, the performance criteria of chemical and physical nature are as follows ... 

Tumor necrosis factor-alpha Loss of biological activity during microencapsulation (29)... 

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