Polymer micelles poly

As has been described in Chapter 4, random copolymers of styrene (St) and 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS) form a micelle-like microphase structure in aqueous solution [29]. The intramolecular hydrophobic aggregation of the St residues occurs when the St content in the copolymer is higher than ca. 50 mol%. When a small mole fraction of the phenanthrene (Phen) residues is covalently incorporated into such an amphiphilic polyelectrolyte, the Phen residues are hydrophobically encapsulated in the aggregate of the St residues. This kind of polymer system (poly(A/St/Phen), 29) can be prepared by free radical ter-polymerization of AMPS, St, and a small mole fraction of 9-vinylphenanthrene [119]. 

Many kinds of nonbiodegradable vinyl-type hydrophilic polymers were also used in combination with aliphatic polyesters to prepare amphiphilic block copolymers. Two typical examples of the vinyl-polymers used are poly(/V-isopropylacrylamide) (PNIPAAm) [149-152] and poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) [153]. PNIPAAm is well known as a temperature-responsive polymer and has been used in biomedicine to provide smart materials. Temperature-responsive nanoparticles or polymer micelles could be prepared using PNIPAAm-6-PLA block copolymers [149-152]. PMPC is also a well-known biocompatible polymer that suppresses protein adsorption and platelet adhesion, and has been used as the hydrophilic outer shell of polymer micelles consisting of a block copolymer of PMPC -co-PLA [153]. Many other vinyl-type polymers used for PLA-based amphiphilic block copolymers were also introduced in a recent review [16]. 

Polymer micelles are nanometer sized (usually several tens of nanometers) self-assembled particles having a hydrophobic core and hydrophilic outer shell composed of amphiphilic AB- or ABA-type block copolymers, and are utilized as drug delivery vehicles. The first polymer micelle-type drug delivery vehicle was made of PEG-b-poly(aspartic acid) (PEG-b-PAsp), immobilizing the hydro-phobic anticancer drugDXR [188-191]. After this achievement by Kataoka et al., a great amount of research on polymer micelles has been carried out, and there are several reviews available on the subject [192-194]. 

Yokoyama, M., M. Miyauchi, N. Yamada, T. Okano, Y. Sakurai, K. Kataoda, and S. Inoue. 1990. Polymer micelles as novel carrier adriamycin-conjugated poly(ethylene glycol)-poly(aspartic acid) block copolymerJ. Control. Rel.11 269-278. 

Amphiphilic poly(ethylene glycol)-alkyl dextran ethers are emerging as vehicles in the oral delivery of poorly water soluble drugs [251,268,269]. They form polymer micelles of low critical association concentrations (CAC) and small micelle sizes in aqueous solution. Particulate delivery systems lead to an enhancement of the absorption efficiency and bioavailability of highly hpophihc drugs orally applied, and provide the drug with some level of pro-... 

Cao T, Yin W, Webber SE. Poly(2-vinylnaphthalene-alt-maleic acid)-graft-polystyrene as a photoactive polymer micelle and stabilizer for polystyrene latexes. Macromolecules 1994 27 7459-7464. 

Yasugi K, Nakamura T, Nagasaki Y, Kato M, Kataoka K. Sugar-installed polymer micelles synthesis and micellization of polyfethylene glycol)-poly(D,L-lactide) block copolymers... 

Yokoyama M, Miyauchi M, Yamada N, Okano T, Sakurai Y, Kataoka K, Inoue S. Polymer micelles as novel drug carrier Adriamycin-conjugated polyfethylene glycol)-poly(aspartic acid) block copolymer. J Control Release 1990 11 269-278. 

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