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Heo, Joo Hyung; Kim, Sun Young; Kim, Hae Sung; Yoo, Ki‐Pung

doi:10.1023/a:1005689204551

Cited by 18 publications

(7 citation statements)

References 5 publications

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“…87,88 However, the solubility of sugars in nonpolar CO 2 is usually low; therefore, a polar co-solvent (such as t-butanol) is usually added. 87 Recently, it was observed that ILs based on BF 4…”

Section: Lipase-catalyzed Synthesis Of Fatty Acid Ester Of D-glucosementioning

confidence: 99%

Lipase dissolution and stabilization in ether-functionalized ionic liquids

2009

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Ionic liquids (ILs) with various structures and properties have been extensively investigated in many biocatalytic reactions and processes. However, although hydrophobic ILs tend to stabilize the insoluble (suspended) enzymes, they usually have low hydrogen-bonding basicity with solutes, which limits the solubility of many substrates (such as D-glucose, ascorbic acid, and cellulose). In contrast, hydrophilic ILs (such as those based on chloride, acetate and dicyanamide) are able to dissolve many of these substances that are not quite soluble in common organic solvents. Unfortunately, enzymes are not always active in these hydrophilic media due to strong interactions (such as H-bonding) between proteins and ILs. To resolve this dilemma, we recently synthesized new acetate-based ILs carrying a long alkyloxyalkyl chain in their cations, and found that these ether-functionalized solvents are lipase-compatible and can dissolve considerable amounts of D-glucose and cellulose (Green Chem., 2008, 10, 696). In this study, we further observed that these ILs could dissolve high concentrations of lipase B from Candida antarctica (CALB) (> 5 mg/mL at 50 • C), as well as other substrates including amino acids and betulinic acid. Therefore, these novel media offer new opportunities for carrying out homogeneous enzymatic reactions, which is practically important for large substrate molecules. In this article, we further confirmed the lipase compatibility of these ILs through the transesterification between ethyl butyrate and 1-butanol. The second derivative infrared spectra of CALB suggest the conservation of secondary structures of proteins in these ILs. We further investigated these ether-functionalized ILs in two important biocatalytic reactions: enzymatic synthesis of methyl-phthalate of betulinic acid, and CALB-catalyzed synthesis of D-glucose fatty acid esters. These substrates are not very soluble in conventional organic solvents, but very soluble in ILs, which improved the catalytic efficiency of these reactions. Moderate to high conversions were achieved in both reactions.

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Section: Lipase-catalyzed Synthesis Of Fatty Acid Ester Of D-glucosementioning

confidence: 99%

Lipase dissolution and stabilization in ether-functionalized ionic liquids

2009

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“…Supercritical carbon dioxide (scCO 2 ), in particular, has attracted attention as an environmentally friendly alternative to organic solvents. Specifically, scCO 2 has a low critical temperature ( T c = 31 °C) and pressure ( P c = 73.8 bar), is nontoxic and nonflammable, has similar properties to nonpolar organic solvents, and is cheap. − …”

Section: Introductionmentioning

confidence: 99%

Preparation of Liposomes Using an Improved Supercritical Reverse Phase Evaporation Method

et al. 2006

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Liposomes of various phospholipids were prepared using an improved supercritical reverse phase evaporation (ISCRPE) method that utilizes supercritical carbon dioxide (scCO(2)) as an alternative to organic solvents. Using this method, in the absence of any organic solvent including ethanol, the maximum trapping efficiency of glucose reached 36% for 20 mM l-alpha-dioleoylphosphatidylcholine (DOPC), compared to less than 10% using the Bangham method. Liposomes prepared by the ISCRPE method were highly stable for one month at room temperature. Freeze fractured TEM observations, osmotic shrinkage measurements, and DSC measurements revealed that the liposomes prepared by the ISCRPE method are unilamellar vesicles with loosely packed phospholipids. Comparison of nitrogen with scCO(2) revealed that the presence of CO(2) is necessary for the formation of liposomes.

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“…Supercritical carbon dioxide (scCO 2 ) is an environmentally friendly alternative to using organic solvent. Furthermore, it has a low critical temperature ( T c = 31 °C) and pressure ( P c = 73.8 bar) and is nontoxic, nonflammable, and has similar properties to nonpolar organic solvents. − In previous papers, we reported the efficient formation of liposomes with carbon dioxide as an alternative to organic solvent. − We believe that the preparation of liposomes with no organic solvent far outweighs the engineering problems that might arise from the use of a high-pressure fluid such as CO 2 .…”

Section: Introductionmentioning

confidence: 99%

One-Step Preparation of Chitosan-Coated Cationic Liposomes by an Improved Supercritical Reverse-Phase Evaporation Method

et al. 2006

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High-pressure carbon dioxide in contact with water dissolves to form carbonic acid, causing a decrease in pH. By use of these characteristics of a CO2/H2O biphasic system, chitosan-coated cationic liposomes of l-alpha-dipalmitoylphosphatidylcholine were successfully prepared by an improved supercritical reverse-phase evaporation (ISCRPE) method. Liposome-chitosan complexes carrying a positive charge were prepared in a single-step procedure without the use of acid or organic solvent, including ethanol. The maximum trapping efficiency of liposomes prepared by the ISCRPE method was 17%, with or without the addition of chitosan, compared to only 2% for liposomes prepared by the Bangham method. Furthermore, the liposomal dispersion was stable at room temperature in a sealed tube for over 30 days.

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Cited by 18 publications

References 5 publications

Lipase dissolution and stabilization in ether-functionalized ionic liquids

Lipase dissolution and stabilization in ether-functionalized ionic liquids

Preparation of Liposomes Using an Improved Supercritical Reverse Phase Evaporation Method

One-Step Preparation of Chitosan-Coated Cationic Liposomes by an Improved Supercritical Reverse-Phase Evaporation Method

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