Proteins block copolymer release

Zentner GM, Rathi R, Shih C, et al. Biodegradable block copolymers for delivery of proteins and water-insoluble drugs. J Control Release 2001 72(l-3) 203-215. 

Bezemer JM, Grijpma DW, Dijkstra PJ, Van Bhtterswijk CA, Feijen J. A controlled release system for proteins based on poly(ether-ester) block-copolymers polymer network characterization. J Control Release 1999 62 393—405. 

Despite typically including PEG as a hydrophilic block for the reduction of protein adsorption, the stabiUly of block copolymer micelles can be affected by proteins, even under well-controlled in vitro conditions. Toncheva et al. found that the stability of PEG-6-poly(ortho ester)-6-PEG micelles in presence of bovine serum albumin depended most on the length of the PEG blocks (Toncheva et al. 2003). A study by Liu et al. found that bovine serum albumin did not affect the stability of PEG-i-poly(5-benzyloxytrimethylene carbonate) micelles, but the dmg release was accelerated in the presence of protein (Liu et al. 2005). 

Chung, H.J., Lee, Y. Park, T.G. 2008, Thermo-sensitive and biodegradable hydrogels based on stereocomplexed Pluronic multi-block copolymers for controlled protein delivery . Journal of Controlled Release, vol. 127, no. 1, pp. 22-30. 

In another example, a hydrophilic star block copolymer was composed of a hyperbranched PEI core, a PLL inner shell and a PEG outer shell. Insulin, as a model protein, can be rapidly and efficiently encapsulated by the synthesized polymer in aqueous phosphate buffer at physiological pH. Complexation between PEI-PLL-Z)-PEG and insulin was demonstrated using native polyacrylamide gel electrophoresis. An in vitro release study by dialysis showed sustained release of the encapsulated protein at physiological pH, and an accelerated release when the pH was decreased. The insulin released from the star block copolymer retained its chemical integrity and immu-nogenicity. Successful in vitro uptake studies of enhanced green fluorescent protein into Ad293 cells mediated by PEI-PLL-Z)-PEG were also performed. ... 

Fig. 4 Novel drug delivery systems using stimuli-responsive polymers, (a) Morphology changes of poly(2-isopropyl- 2-oxazoline) (PiPrOx) and poly(benzyl ether)dendrons dendritic-linear block copolymers conjugates are Temperature- and pH-dependent.[105] (Copyright 2012, Royal Society of Chemistry) (b) Protein-binding-induced disassembly of dendron-based micelles. This inducible micelle disassembly is selective to the targeted protein and the disassembly can mediate release of the encapsulated therapeutic drugs.[106] (Copyright 2010, American Chemical Society)...

Polymeric micelle systems (PMS) are made by the self-assembly of amphiphilic block copolymers in an aqueous enviromnent. The important features of PMS are drug solubilization, controlled drug release, and drug targeting [26]. This chapter focuses and discusses the current scenario of natural biodegradable polymeric-based nanoblends for protein and gene delivery with a special emphasis on the pharmaceutical and biomedical approaches. 

PLA w as blended with PEO-PPO-PEO block copolymers. The blftck copolymers were used to increase the bydrophilicity of tile sy.sf.eiii. No effect of PEO-PPO-PEO block copolymers on PLA degradation in water. Controlled release of protein. BSA was used as a model protein. Park et al., 1992... 

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