Page 360 - Biomedical Engineering and Design Handbook Volume 1, Fundamentals

BIOPOLYMERS 337

structures), or nondegradable materials similar to those used in dialysis membranes (e.g., polyacry-
lates). More recent and successful applications have been in the area of biotechnology. 40
The main focus of the field has been on regeneration scaffolds, and this area is very active with
clinical products in large scale use. Degradable polymers are the main materials used and include the
41
polymers already discussed, as well as others such as small intestine submucosa (“SIS”). This mate-
rial, similar to the composition of natural sausage casing, is typically derived from the intestinal extra-
cellular matrix of pigs, and has been used in over a million human patients for multiple applications.
Other natural materials are used (fibrin glue, collagen, alginate, etc.) and most of the degradable mate-
rials mentioned earlier in this chapter. In particular, most work using synthetic biomaterials has
involved polylactic acid and copolymers with glycolic acid. The main differences involved for this
application include surface modification for selective cell attachment, controlled release of signal
molecules (usually proteins), and geometry (e.g., foams, fibers, and patches). There are many books
and research groups focused on this area, and most physicians feel that it has great promise for the
future.

REFERENCES

1. Encyclopedia of Polymer Science and Engineering, Vol. 17. New York: Wiley, 1985, pp. 198–257.
2. Chen, X. H., McCarthy, S. P. and Gross, R. A. “Synthesis and characterization of [L]-lactide-ethylene oxide
multiblock copolymers,” Macromolecules, 30(15):4295–4301 (1997).
3. Cohn, D., and Younes, H. “Biodegradable Peo/Pla block copolymers,” Journal of Biomedical Materials
Research, 22(11):993–1009 (1988).
4. Hu, D. S. G., and Liu, H. J. “Structural-analysis and degradation behavior in polyethylene- glycol poly
(L-lactide) copolymers,” Journal of Applied Polymer Science, 51(3):473–482 (1994).
5. Li, Y. X., and Kissel, T. “Synthesis and properties of biodegradable aba triblock copolymers consisting of
poly(L-lactic acid) or poly(L-lactic-co-glycolic acid) a-blocks attached to central poly(oxyethylene)
b-blocks,” Journal of Controlled Release, 27(3):247–257 (1993).
6. Yamaoka, T. et al. “Synthesis and properties of multiblock copolymers consisting of poly(L-lactic acid) and
poly(oxypropylene-co-oxyethylene) prepared by direct polycondensation,” Journal of Polymer Science Part
a-Polymer Chemistry, 37(10):1513–1521 (1999).
7. Razatos, A. et al. “Force measurements between bacteria and poly(ethylene glycol)-coated surfaces,”
Langmuir, 16(24):9155–9158 (2000).
8. Vigo, T. L., and Leonas, K. K. “Antimicrobial activity of fabrics containing crosslinked polyethylene
glycols,” Textile Chemist and Colorist & American Dyestuff Reporter, 1(1):42–46 (1999).
9. Park, K. D. et al. “Bacterial adhesion on PEG modified polyurethane surfaces,” Biomaterials,
19(7–9):851–859 (1998).
10. Guo, Y. Q., and Hui, S. W. “Poly(ethylene glycol)-conjugated surfactants promote or inhibit aggregation of
phospholipids,” Biochimica et Biophysica Acta-Biomembranes, 1323(2):185–194 (1997).
11. Slepushkin, V. A. et al. “Sterically stabilized pH-sensitive liposomes—intracellular delivery of aqueous
contents and prolonged circulation in vivo,” Journal of Biological Chemistry, 272(4):2382–2388 (1997).
12. Woodle, M. C., Newman, M. S., and Cohen, J. A. “Sterically stabilized liposomes—physical and biological
properties,” Journal of Drug Targeting, 2(5):397–403 (1994).
13. Dunn, S. E., Brindley, A., Davis, S. S., Davies, M. C., and Illum, L. “Polystyrene-poly(ethylene glycol)
(PS-PEG 2000) particles as model systems for site-specific drug-delivery: 2. The effect of peg surface-den-
sity on the in vitro cell-interaction and in vivo biodistribution,” Pharmaceutical Research, 11(13):1016–1022
(1994).
14. Verrecchia, T. et al. “Non-stealth (poly(lactic acid albumin)) and stealth (poly(lactic acid-polyethylene
glycol)) nanoparticles as injectable drug carriers,” Journal of Controlled Release, 36(1–2):49–61 (1995).
15. Maruyama, K., Takahashi, N., Tagawa, T., Nagaike, K., and Iwatsuru, M. “Immunoliposomes bearing poly-
ethyleneglycol-coupled Fab’ fragment show prolonged circulation time and high extravasation into targeted
solid tumors in vivo,” Febs Letters, 413(1):177–180 (1997).