Blend polyanhydride

Whether in copolymers or blends, inhomogeneous erosion has a nontrivial effect on drug release kinetics as will be shown later. Leong et al. (1985) demonstrated that the pH of the degradation media also has a dramatic effect on the erosion rate, which increases with increasing pH. The acceleration of degradation of polyanhydrides with increase in pH is widely reported and has been used to speed up experiments (Shakesheff et al., 1994). 

Polyanhydrides Polyanhydrides have a hydrophobic backbone with a hydrolytically labile anhydride linkage. These polymers widely vary in chemical composition and include aliphatic, aromatic, and fatty acid-based polyanhydrides. The rate of degradation depends on the chemical composition of the polymer. In general, aliphatic polyanhydrides degrade more rapidly than the aromatic polymer. Hence, copolymer blends with varying ratios of aliphatic-to-aromatic polyanhydrides can be synthesized to suit specific applications. 

Polyanhydride Nanoparticles Polyanhydrides have been more commonly used to prepare microparticles than nanoparticles. However, the technology is adaptable for nanoparticles. The transfection efficiency of firefly luciferase DNA was enhanced when delivered in nanoparticles prepared from polyanhydride-lactic acid blends, demonstrating the potential application in gene delivery [120], The degradation and elimination of polyanhydrides have been reviewed [97], In vivo, the anhydride bond degrades to form diacid monomers that are eliminated from the body. 

Kipper, M.J. Seifert, S. Thiyagarajan, P. Narasimhan, B. Understanding polyanhydride blend phase behavior using scattering, microscopy, and molecular simulations. Polymer 2004, 45 (10), 3329-3340. 

The physical and mechanical properties of polyanhydrides can be altered by modification of the polymer structure with a minor change in the polymer composition. Several such modifications include the formation of polymer blends, branched and crosslinked polymers, partial hydrogenation and reaction with epoxides. 

Biodegradable polymer blends of polyanhydrides and polyesters have been used as drug carriers [59], Polyflactic acid) (PLA), polyfhydroxybutyrate) (PHB), and poly(caprolactone) (PCL), of 2000 and 50000 molecular weights were mixed with poly(sebacic anhydride) (PSA), and the properties of these mixtures were studied. Mixtures of PHB and low molecular weight PLA or PCL formed uniform blends with various amounts of PSA. These blends possess different physical and mechanical properties compared to the parent polymers. The release rate of drugs from these polymeric blends increases with the increase in the content of the rapidly degrading component, PSA. 

Polyanhydride Blends with polyanhydrides or other PSA blend PLA... 

L. Chen, H. Wang, J. Wang, M. Chen, L. Shang, Ofloxacin-delivery system of a polyanhydride and polylactide blend used in the treatment of bone infection, J. Biomed. Mater. Res. B Appl. Biomater. 83 (2007) 589-595. 

The properties of polyanhydrides ean be modified by ehanging polymer composition and structure. This is obtained by realizing copolymers, polymer blends, erosslinking between ehains, partial hydrogenation and reaction with epoxides. Low moleeular weight PLA, PHB and PCL are miscible with polyanhydrides whereas high moleeular weight polyesters are not. 

The physical and mechanical properties of polyanhydrides can be altered by minor modifications. Biodegradable polymer blends of polyanhydrides and polyesters have been investigated as dmg carriers (Leong et al., 1984). A polymeric blend of poly (trimethylene carbonate) (PTMC) with poly(adipic anhydride) (PAA) and the matrix of PTMC—PAA blend was found to be biocompatible in vitro and in vivo experiments as well as a promising candidate for controlled drug delivery erosion with tuneable erosion rate achieved by varying the proportion of PTMC and PAA (Edlund and... 

Albertsson, 1999). In general, polyanhydrides of different structures form uniform blends with a single melting temperature. Low molecular weight PLA, PHB, and pol-y(caprolactone) (PCL) are miscible with polyanhydrides, while high molecular weight polyesters M > 10,000) are not compatible with poly anhydrides. 

Abuganima, E. (1996) Syrithe.sis and characterization of copolymers and blends of polyanhydrides and polye.sters, M.Sc. Thesis, The Hebrew L niv. ofjerusalem. 

Bhardwaj and Mohanty [8] proposed and demonstrated a new industrially relevant methodology to develop a polylactide (PLA)-based nano blend having outstanding stiffness-toughness balance. In this approach, a hydroxyl functional hyper branched polymer (HBP) was in situ cross-linked with a polyanhydride (PA) in the PLA matrix during melt processing. There was formation of new HBP-based cross-linked particles in the PLA matrix. TEM and AFM revealed the sea-island morphology of... 

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