Poly ethylene glycol acid-sensitive

Na, K., Lee, K. H., Lee, D. H., and Bae, Y. H. (2006), Biodegradable thermo-sensitive nanoparticles from poly(L-lactic acid)/poly(ethylene glycol) alternating multi-block copolymer for potential anti-cancer drug carrier, Eur. J. Pharm. Sci., 27(2-3), 115— 122. 

This chapter covers the applications of Fourier transform infrared (FTIR) and Raman spectroscopy to the characterization of water-soluble polymers. The structural analysis of poly(oxyethylene), poly ethylene glycol), poly methacrylic acid), and poly acrylic acid), and the interactions of selected polymers with solvents and surfactants are presented. Structural features of these compounds in the crystalline and melt states are compared with their structural features upon dissolution in aqueous solvents. Special emphasis is given to the recent studies of the interactions between water-soluble polymers or copolymers and solvents or surfactants. New experimental approaches and the sensitivities of both FTIR and Raman spectroscopy to monitor such interactions are presented. 

With regard to protein oral delivery, an experiment was conducted on a pH-sensitive hydrogel polymer composed of poly[methacrylic acid-graft-poly(ethylene glycol)] (P(MAA-g-EG)) (77-80). The P(MAA-g-PEG) nanosphere system demonstrated low cytotoxicity and was capable of opening... 

Fig. 2 Multifunctional polymeric micelles composed of a block copolymer of poly(ethylene glycol) and polyaspartate with tumor selectivity for active drug targeting and pH sensitivity for intracellular site-specific drug transport. Folic acid with high tumor affinity due to the overexpression of its receptors was conjugated onto the surface of the micelle (adapted from Ref. [114] with permission)...

Finally similar transition can be induced by using UV-sensitive groups such as poly(ethylene oxide)-poly(methylphenylsilane) (PEO-PMPS) and azobenzene-containing poly(methacrylate)-poly(acrylic acid) (PAA-PAzoMA) [59]. More recently Mabrouk et al. [60] have shown an asymmetric polymersomes whose membrane has only one leaflet composed of UV-sensitive liquid-crystalline copolymer Poly(ethylene glycol)-poly(4-butyloxy-2-(4-(methacryloyloxy)butyloxy)-4-(4-butyloxybenzoyloxy)azobenzene) (PEG-fe-PMAazo444). Once exposed to UV light these polymersome burst due to changes in the spontaneous curvature of the membrane. 

Thermo-sensitive copolymer PEG-PLGA-PEG, which consists of poly(ethylene glycol) (PEG) and poly(D,L-lactic acid co-glycolic acid) (PLGA). 

Naficy, S. Razal, J. M. Whitten, P. G. Wallace, G. G. Spinks, G. M., ApH-Sensitive, Strong Double-Network Hydrogel Poly(ethylene glycol) Methyl Ether Methacrylates-Poly(acrylic acid). J. Polym. Sci., PartB Polym. Phys. 2011, 50, 423-430. 

The sensitivities of a wide range of other acrylate and methacrylate polymers to y radiation have also heen investigated, including poly(acrylic acid) (85,253), poly(methacrylic acid) (85,254-263), poly(hydroxyethyl methacrylate) (264,265), polymethacrylates with longer ester side-chains (266,267), and poly(ethylene glycol dimethacrylate) (268). In general, the behaviors of these polymers mirror the behaviors of the related methyl ester polymers, but some observations are worthy of special mention. 

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