Bioactive substances, controlled release

An important number of these substances have an industrial origin. Some of them, like the pesticides, arrive intentionally in the environment and their use and release should be theoretically controlled. However, many of them have not been purposely produced as bioactive substances but more as components or additives of certain materials. Their significant growth in the chemical industry has not only been produced as a consequence of the discovery of new active principles in the pharmaceutical or pesticide area, but also because of the expansion of new technologies (electronics, containers, textiles, plastics, resins, foams, etc.), that require the development of new materials and substances with particular features. Most of these substances enter or are discharged to water and air sources without regulated controls. Wastewater treatment plants (WWTPs) are often not yet adapted to completely remove them, and therefore these new compounds can be found to some extent in wastewater effluents as well as in soil and sludge. 

Immobilization and Controlled Release of Bioactive Substances from Stimuli-Responsive Hydrogels... 

Dynamic swelling parameters of bioactive substances into hydrogel matrices are summarized in Table 19.1. The values of n>0.5 indicate that the loading mechanism of bioactive substances deviates from Fickian diffusion. For NIPA-APSA and NIPA-AA/Richlocaine systems the diffusion mechanism is relaxation-controlled because their n values are close to 1. Temperature-dependent release of richlocaine from the NIPA-AA hydrogels is shown in Figs. 19.3 and 19.4. 

Controlled release of a chemical substance can be effected by diffusion or erosion of a polymer matrix ( 1). This method has been used with considerable success in the delivery of bioactive compounds in agriculture and, to some extent, in dispensing drugs by absorption through tissue upon contact. 

Controlled Release Society. 3650 Annapolis Lane North, Suite 107, Minneapolis, MN 55447, U.S.A. Phone +1 763-512-0909, Fax +1 763-765-2329. E-mail director controlledrelease.org. URL http //www.controlledrelease.org. The Controlled Release Society (CRS) is an international organization which serves 3000 members from more than 50 countries. Two-thirds of the CRS membership represents industry and one-third represents academia and government. The organization is dedicated to improving quality of life by advancing science, technology, and education in the field of controlled delivery of bioactive substances. CRS publishes the Journal of Controlled Release and sponsors several meetings, workshops, and symposia. 

Microstructure and viscosity are dependent on the chemical composition Used as immobilization matrices for cells and enzymes, controlled release of bioactive substances, injectable microcapsules for treating neurodegenerative and hormone deficiency diseases Lacks yield value... 

Edible coatings cannot be typically considered packages bnt rather physical food protecting barriers, which can additionally act as carriers of active and/or bioactive substances and controlled release of flavor molecules, giving them an added-valne. Edible film can carry active components, snch as flavors and other food additives, in the form of hard capsules, soft gel capsules, microcapsules, soluble strips, flexible pouches, coatings on hard particles, and others. ... 

Cambridge, Massachusetts, USA, from 1990-1992. His research interests fall in the areas of delivery systems from naturally occurring polymers for the controlled release of bioactive substances, functional composites from biomass or biobased materials, smart packaging technology and material, and biomedical devices for tissue regeneration, pharmaceutical, and cosmetic applications. 

Binary nanocomposites of layered sihcate/ maleic copolymers can contain different bioactive substances which can be released in time and at low and controlled concentrations (bone growth factors, titania or carbon aerogels, hydrolyzed collagen, anticancer compounds, antimicrobial antioxidants, etc.). 

---