Hydrogelation control

Hydrogels. Controlled swelling of hydrophilic polymers, derived from the glossy/mbbery properties of polymers, is used to control the rate of dmg release from matrices. In the mbbery state, accompHshed by lowering the polymer s glass-transition temperature to an appropriate level, the dispersed dmg diffuses as the polymer swells in the presence of water. 

Franssen, 0., Vandervennet, L., Roders, P, and Hennink, W. E. Degradable dextran hydrogels Controlled release of a model protein from cylinders and microspheres. J. Contr. Rel. 60 211-221, 1999. 

Figure 9.17 Release of anticancer drugs from poly(HEMAF-collagen hydrogels. Controlled release of 5-fluorouracil 130), mitomycin C (M, 334), and bleomycin Ml 1,417) into phosphate-buffered water at 37 °C from p(HEMA) polymerized in the presence of drug and 5% eoUagen. The hydrogels were hydrated ( 40% water) throughout the experiment. Adapted from [57].

The most frequent observation is a quantitative reduction in the amount of a particular protein adsorbed to the hydrogel in comparison to a non-hydrogel, control (typically hydrophobic) surface. 

Peppas, N.A. and Klier, J. 1991. Controlled release by using polyfmethaciylic acid-g-ethylene glycol) hydrogels. / Control Release. 16 203-214. 

As already reflected by the number of review papers, the interest in biomedical applications of polyphosphazenes continues to grow. The biodegradable polymer NP(NHC6H4C02H-4)i.8(NHC6H4C02H-4)o.2 n has been prepared and fully characterized. The carboxylato groups can react with Ca -ions to form crosslinks and to convert the water-soluble polymer to a hydrogel. Controlled drug release experiments have been carried out for chitosan en-... 

R.A. Siegel, M. Falamarzian, B.A. Firestone, and B.C. Moxley, pH-controlled release from hydrophobic/polyelectrolyte copolymer hydrogels,/ Control. Release,8 2), 179-182,1988. 

Yamamoto, M. et al.. Bone regeneration by transforming growth factor bl released from a biodegradable hydrogel, /. Control. Release, 64,133,2000. 

---