Supercritical Carbon Dioxide-Processed Dispersed Polystyrene−Clay Nanocomposites

CO2 -Assisted Conversion of Crystal Two-Dimensional Molybdenum Oxide to Amorphism with Plasmon Resonances

Localized surface plasmon resonances (LSPRs) of ultra-thin two-dimensional (2D) nanomaterials have opened up a new regime in plasmonics in the last several years. 2D plasmonic materials are currently concentrated on the crystal structure, with amorphous materials hardly being reported because of their limited preparation methods rather than undesired plasmonic properties. Taking molybdenum oxides as an example, herein, we elaborate the 2D amorphous plasmons prepared with the assistance of supercritical CO₂ . In brief, we examine the reported characteristic plasmonic properties of molybdenum oxides, and applications of supercritical CO₂ in formations of 2D layer materials as well as introduced phase and disorder engineering based on our research. Furthermore, we propose our perspective on the development of 2D plasmons, especially for amorphous layer materials in the future.

Supercritical carbon dioxide processed resorbable polymer nanocomposite bone graft substitutes

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 scCO(2) 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.