Lipase Activity and Stability in Supercritical Carbon Dioxide

Nakamura, Kozo; Min, Young; Yamada, Yukie; Yano, Toshimasa

doi:10.1080/00986448608911384

Cited by 154 publications

(44 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The properties of supercritical fluids, in that they possesses densities and solvating powers similar to those of liquids, but have the diffusivity and viscosity similar to those of gases, make them ideal media for such chemical reactions. In the mid-1980s the field of supercritical fluids was applied by several groups to bio-catalytic reactions, allowing control of such processes by simply altering either temperature or pressure (Hammond et al 1985 ;Randolph et al 1985 ;Nakamura et al 1986). Supercritical fluid technology was used to develop protein powders of defined size that could be utilized for drug delivery without the use of solvents (Tom et al 1993 ;Winters et al 1996).…”

Section: Supercritical Carbon Dioxide Processingmentioning

confidence: 99%

Growth factor release from tissue engineering scaffolds

Whitaker

Quirk

Howdle

et al. 2001

Journal of Pharmacy and Pharmacology

258

160

View full text Add to dashboard Cite

Synthetic scaffold materials are used in tissue engineering for a variety of applications, including physical supports for the creation of functional tissues, protective gels to aid in wound healing and to encapsulate cells for localized hormone-delivery therapies. In order to encourage successful tissue growth, these scaffold materials must incorporate vital growth factors that are released to control their development. A major challenge lies in the requirement for these growth factor delivery mechanisms to mimic the in-vivo release profiles of factors produced during natural tissue morphogenesis or repair. This review highlights some of the major strategies for creating scaffold constructs reported thus far, along with the approaches taken to incorporate growth factors within the materials and the benefits of combining tissue engineering and drug delivery expertise.

show abstract

Section: Supercritical Carbon Dioxide Processingmentioning

confidence: 99%

Growth factor release from tissue engineering scaffolds

Whitaker

Quirk

Howdle

et al. 2001

Journal of Pharmacy and Pharmacology

258

160

View full text Add to dashboard Cite

show abstract

“…In addition to these benefits, supercritical fluids (SCFs) are recyclable solvents that aid significantly in sample preparation (1). SCFs are also ideal dispersants in which to investigate the effect of solvent physical properties on an enzyme-catalyzed reaction (2)(3)(4)(5)(6)(7).…”

mentioning

confidence: 99%

Biocatalytic synthesis of acrylates in supercritical fluids: tuning enzyme activity by changing pressure.

Kamat

Iwaskewycz

Beckman

et al. 1993

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Supercritical fluids are a unique class of nonaqueous media in which biocatalytic reactions can occur. The physical properties ofsupercritical fluids, which include gas-like diffusivities and liquid-like densities, can be predictably controlled with changing pressure. This paper describes how adjustment ofpressure, with the subsequent predictable changes of the dielectric constant and Hildebrand solubility parameter for fluoroform, ethane, sulfur hexafluoride, and propane, can be used to manipulate the activity oflipase in the transesterification of methylmethacrylate with 2-ethyl-1-hexanol. Of particular interest is that the dielectric constant of supercritical fluoroform can be tuned from approximately 1 to 8, merely by increasing pressure from 850 to 4000 psi (from 5.9 to 28 MPa). The possibility now exists to predictably alter both the selectivity and the activity of a biocatalyst merely by changing pressure.When the temperature and pressure of a material exceed, or approach, the critical points for that material, the physical properties ofthe "solvent" become sharply dependent on the pressure encountered by the material. Since density is controllable via adjusting either pressure or temperature, it is possible to tune the solvent physical properties by changing reaction conditions, rather than the solvent itself. In addition to these benefits, supercritical fluids (SCFs) are recyclable solvents that aid significantly in sample preparation (1). SCFs are also ideal dispersants in which to investigate the effect of solvent physical properties on an enzyme-catalyzed reaction (2-7).Enzymes are known to function in both aqueous and organic media (for instance, see ref. 8 or ref. 9). Studies ofbiocatalysts in nonaqueous environments have led to a deeper understanding of how enzymes function in unnatural surroundings as well as in water (10). A detailed understanding of environment/ structure/function relationships for proteins suspended in organic media may enable predictive control of enzyme function merely by "solvent engineering." Much research has been dedicated to furthering our understanding of how enzymatic activity is related to the physical properties of the solvent in which it is placed. The driving force for much ofthis research is the fact that when a lyophilized enzyme particle is suspended in an organic solvent, the activity, specificity, and stability of the catalyst depend on the solvent. If one could predict how a particular solvent would affect an enzyme, then, as described above, rational solvent engineering would be a simple way to tune biocatalyst function.Although determining the effect of changing solvent on activity and specificity can suggest interesting correlations between solvent and enzyme properties, the question of why similar solvents can have such different abilities to support biocatalytic reactions always remains. For example, lipasecatalyzed transesterification of acrylates in hexane, heptane, octane, nonane, and decane gives significantly differing rates that no simple ...

show abstract

“…The formation of a thick adsorbed layer was presumed not to end abruptly at the critical temperature but to break down at a temperature exceeding Te by 10 K. This phenomenon referred to in (1) and (2) has been called "prewetting" of a solid material by the supercritical fluid. The peak in the near-critical isotherms had not been previously observed by other researchers, who had used highly porous solids as adsorbents differing from a smooth-surface material like graphite.…”

mentioning

confidence: 99%