Supercritical carbon dioxide processed resorbable polymer nanocomposite bone graft substitutes

Kevin C. Baker, Mihai Manitiu, Robert Bellair, Carly A. Gratopp, Harry N. Herkowitz, Rangaramanujam M. Kannan

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


The development of synthetic bone graft substitutes is an intense area of research due to the complications associated with the harvest of autogenous bone and concerns about the supply of allogenic bone. Porous resorbable polymers have been used extensively in hard tissue engineering applications, but currently lack load-bearing capacity. Supercritical carbon dioxide (scCO 2) processing is used as a novel method to simultaneously impart a porous structure and disperse a nano-clay in a resorbable polymer matrix suitable for load-bearing applications. Porous resorbable polylactic acid (PLA)/cloisite clay nanocomposite constructs prepared using scCO2 processing exhibit a 2.5-fold increase in compressive strength compared with pure polymer constructs. The resulting mechanical properties are comparable with human cancellous and cortico-cancellous bone. In addition to the significant improvements in mechanical properties, the nanocomposite constructs display a biocompatibility greater than that of polystyrene culture plate controls. Furthermore, calcium phosphate-rich deposits could clearly be seen on the surface of the constructs, as well as at the center of the cultured constructs, indicating that osteoblasts are able to penetrate the porous network of the nanocomposite constructs. Cellular infiltration of these constructs is important for their in vivo use as bone graft substitutes. The diameter of the pores suggests that these constructs would also support neovascularization, which is integral for nutrient transport.

Original languageEnglish (US)
Pages (from-to)3382-3389
Number of pages8
JournalActa Biomaterialia
Issue number9
StatePublished - Sep 2011
Externally publishedYes


  • Bone graft
  • Bone tissue engineering
  • Nanocomposite
  • Polylactic acid
  • Scaffold

ASJC Scopus subject areas

  • Biotechnology
  • Biomaterials
  • Biochemistry
  • Biomedical Engineering
  • Molecular Biology


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