Polypeptides, controlled polymer release

Muscles contract and expand in response to electrical, thermal, and chemical stimuli. Certain polymers, such as synthetic polypeptides, are known to change shape on application of electric current, temperature, and chemical environment. For instance, selected bioelastic smart materials expand in salt solutions and may be used in desalination efforts and as salt concentration sensors. Polypeptides and other polymeric materials are being studied in tissue reconstruction, as adhesive barriers to prevent adhesion growth between surgically operated tissues, and in controlled drug release, where the material is designed to behave in a predetermined matter according to a specific chemical environment. 

The preceding studies, as well as other studies on controlled release from numerous other laboratories are but examples of how polymers may be useful in controlling drug release. These delivery concepts may not only be of value in their own right, but will hopefully stimulate additional research in the release of polypeptides, the creation of new bioerodible polymers, and the design of pulsatile delivery systems. 

Qiu, S., Huang, X., Dai, X.-H. et al. (2009) Star-shaped polypeptide/glycopolymer biohybrids synthesis, self-assembly, biomolecular recognition, and controlled drug release behavior. Journal of Polymer Science Part A Polymer Chemistry, 47,2009-2023. 

Wang K, Luo G-F, Liu Y, Li C, Cheng S-X, Zhuo R-X, Zhang X-Z (2012) Redox-sensitive shell cross-linked PEG-polypeptide hybrid micelles for controlled drug release. Polym Chem 3 1084-1090... 

Hutchinson, F. G., and Burr, B. J. A., 1990, Biodegradable polymer systems for the sustained release of polypeptides, J. Controlled Release 13 279-294. 

Langer, R., and Moses, M., 1991, Biocompatible controlled release polymers for delivery of polypeptides and growth factors, J. Cell. Biochem. 45 340-345. 

The literature on controlled release from amphiphilic polymer aggregates is reviewed. Two terms, biodegradation and organisation of polymers, are discussed as characteristic points for the authors approach to polymer aggregates. Microcapsules are considered, with particular reference to sustained release from polypeptide microcapsules, pH-responsive release from polypeptide microcapsules, thermoresponsive microcapsules, and degradation. Microspheres are then discussed and polypeptide vesicles are examined. 81 refs. JAPAN... 

Wt of polypeptide drug, using insulin, calcitonin, trypsin inhibitor and angiotensin II as model polypeptides. Release rates fix>m these systems were controlled by varying the molecular weight (M. Wt.) of the polymers (19), and insulin was used as a model polypeptide drug. 

The area of applied bioactive polymeric systems includes such diverse entities as controlled release systems (erodable systems, diffusion controlled systems, mechanical systems and microcapsules), and biologically active polymers, such as natural polymers, synthetic polypeptides, pseudo-enzymes, pseudo-nucleic acids and polymeric drugs. The area can also include immobilized bioactive materials, such as immobilized enzymes, antibodies and other bioactive agents and the area of artificial cells. This Chapter reviews the general field of biologically active synthetic and modified natural macromolecules with an emphasis on their common characteristics, problems and applications. The areas reviewed include both medical and non-medical applications for both controlled release systems and polymers that exhibit direct biological activity. 

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