Bioactive agents biocompatibility

Figure 1.1 Development of polymeric biomaterials for controlled delivery tissues. This book will consider several aspects of the development of delivery systems including the characterization of biocompatible polymers, methods for incorporating bioactive agents into polymer matrices and microspheres, and methods for quantitative analysis of kinetics of drug release. Since these devices are developed for the delivery of agents to tissues, a critical component in this analysis will be the consideration of drug transport through the local tissue surrounding the implant.

Cohen and co-workers combined the unique characteristics of acetyl-dextran (Ac-DEX) and spermine with small interfering RNA - a class of double-stranded RNA molecules, 20-25 base pairs in length - as a delivery system. Ac-DEX possesses several characteristics suitable for the delivery of bioactive agents such as proteins. The novel system combined ease of synthesis and biocompatibility with the advantage of controlled release, i.e., sensitivity to physiologically relevant acidic conditions. Acid-catalysed hydrolysis of spermine-Ac-DEX generated spermine-modified dextran, which could be further metabolised in vivo by enzymes [13]. 

Hydrogels are macromolecular materials with a water content of 30 to 90%. They provide fairly good biocompatibility, being adequate materials for catheter sutures, blood detoxificants, artificial sensors, ophthalmologic protection (contact lenses, artificial cornea), conjunctive tissue substitution, bum therapy, dental implants, aesthetic surgery, and immobilization of bioactive agents. 

Studies to date indicate that PLA delivery devices containing bioactive agents are biocompatible and when used in therapeutic applications in vivo do not exhibit imtow-ard reactions either locally or systemically [54]. 

Due to their highly biocompatible nature, dendritic PGs have a broad range of potential applications in medicine and pharmacology. The versatility of the polyglycerol scaffolds for application in the biomedical field has recently been reviewed [131], and a number of examples were described, therein, e.g., smart and stimuli-responsive delivery and release of bioactive molecules, enhanced solubilization of hydrophobic compounds, surface-modification and regenerative therapy, as well as transport of active agents across biological barriers (cell-membranes, tumor tissue, etc.). 

Wang [3] prepared the amphiphilic biocompatible cyclodextrin graft polymer, poly(ethylene glycol-g-cyclodextrin), (III), containing modified cyclodextrin which was used as a bioactive drug delivery agent. 

Among new applications [192,193] attention has been focused on the biocompatible, bioactive, and biodegradable properties. Dopamine and several enzymes, e.g., trypsine, have been covalently bound to polyphos-phazene chain. AJso anestisics, steroids, and antibacterial agents may be linked to polyphosphazene with promising pharmaceutical applications. 

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