Publications (4)8.23 Total impact
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Article: Lipase immobilization on smectite nanoclays: characterization and application to the epoxidation of alpha-pinene.
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ABSTRACT: The immobilization of lipase B from Candida antarctica on smectite group nanoclays (Laponite, SWy-2 and Kunipia), as well as on their organically modified derivatives, was investigated. A combination of techniques, namely X-ray diffraction, thermal analysis, X-ray photoelectron and FT-IR spectroscopy, was used for characterization of the novel immobilized biocatalyst. Structural and biochemical characterization have revealed that the hydrophobic microenvironment created by the organo-modified clays induces minor changes on the secondary structure of the enzyme, resulting in enhanced catalytic behaviour in hydrophobic media. The immobilized lipase on such modified nanoclays can be effectively applied for the indirect epoxidation of alpha-pinene using hydrogen peroxide as substrate. The amount of alpha-pinene epoxide produced in a single-step biocatalytic process is up to 3-fold higher than that of free enzyme or enzyme immobilized in non-modified clays. Moreover, lipase immobilized in modified clays retains up to 90% of its initial activity, even after 48h of incubation in the presence of oxidant, and up to 60% after four reaction cycles, while other forms of the enzyme retain less than 10%.Bioresource technology 11/2009; 101(6):1587-94. · 4.25 Impact Factor -
Article: NaCl multi-layer islands grown on Au(111)-([Formula: see text]) probed by scanning tunneling microscopy.
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ABSTRACT: The growth of multi-layer NaCl islands on Au(111)-([Formula: see text]) surfaces was investigated using scanning tunneling microscopy (STM). We observed that the aspect of the NaCl islands drastically differs depending on the tunneling conditions. It is therefore possible to observe the layers forming an NaCl island or to image the gold reconstruction below the first NaCl layer. Atomically resolved STM images obtained on the first NaCl layer demonstrate that NaCl grows as an epitaxial crystalline film on Au(111)-([Formula: see text]). STM images also suggest that some NaCl layers can be non-crystalline.Nanotechnology 12/2008; 19(49):495307. · 3.98 Impact Factor -
Article: NaCl multi-layer islands grown on Au(111)-(22 × √3) probed by scanning tunneling microscopy
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ABSTRACT: The growth of multi-layer NaCl islands on Au(111)-(22 × √3) surfaces was investigated using scanning tunneling microscopy (STM). We observed that the aspect of the NaCl islands drastically differs depending on the tunneling conditions. It is therefore possible to observe the layers forming an NaCl island or to image the gold reconstruction below the first NaCl layer. Atomically resolved STM images obtained on the first NaCl layer demonstrate that NaCl grows as an epitaxial crystalline film on Au(111)-(22 × √3). STM images also suggest that some NaCl layers can be non-crystalline. -
Article: Lipase immobilization on smectite nanoclays: Characterization and application to the epoxidation of α-pinene
[show abstract] [hide abstract]
ABSTRACT: The immobilization of lipase B from Candida antarctica on smectite group nanoclays (Laponite, SWy-2 and Kunipia), as well as on their organically modified derivatives, was investigated. A combination of techniques, namely X-ray diffraction, thermal analysis, X-ray photoelectron and FT-IR spectroscopy, was used for characterization of the novel immobilized biocatalyst. Structural and biochemical characterization have revealed that the hydrophobic microenvironment created by the organo-modified clays induces minor changes on the secondary structure of the enzyme, resulting in enhanced catalytic behaviour in hydrophobic media. The immobilized lipase on such modified nanoclays can be effectively applied for the indirect epoxidation of α-pinene using hydrogen peroxide as substrate. The amount of α-pinene epoxide produced in a single-step biocatalytic process is up to 3-fold higher than that of free enzyme or enzyme immobilized in non-modified clays. Moreover, lipase immobilized in modified clays retains up to 90% of its initial activity, even after 48 h of incubation in the presence of oxidant, and up to 60% after four reaction cycles, while other forms of the enzyme retain less than 10%.Bioresource Technology.
