Effective immobilization of Candida antarctica lipase B in organic-modified clays: Application for the epoxidation of terpenes

Enzyme Immobilization on Layered and Nanostructured Materials

“…In most cases, as enzyme loading increases, the intensity of the refl ection increases, confi rming enhanced intercalation of enzyme or a higher degree of ordering [25,58] , while other studies showed that the enzyme loading leads to exfoliated nanocomposite structures [56,57] . In the case of organo -modifi ed clays, the interaction between the clay and the surfactant led to a shift of the d 001 diffraction peak of the organo -modifi ed clay toward lower 2 θ values, implying the expansion of the interlayer space due to the alkylammonium intercalation [56] .…”

“…Concerning the site of immobilization, it is proposed that the enzyme molecules are anchored on the external surface, the edges of the clay sheets, or intercalated within the interlayer space of the clay [24,56,57] . Taking into consideration that the enzyme molecule in most cases is bigger than the clay galleries, the molecule is not expected to intercalate between the clay nanosheets [56] .…”

“…Towards to this direction, palygorskites were modifi ed either by acid treatment, or reacting the surface silanol groups present with 3 -aminopropyltriethoxysilane, or treating with a quaternary ammonium compound (octodecyl trimethyl ammonium chloride), to produce derivatives with suitable functional groups for further use as supports for enzyme immobilization [64] . Also smectite clays such as laponite, kunipia and SWy -2 were modifi ed by treating with a cationic surfactant (octadecyl trimethyl ammonium bromide) [65] for the immobilization of CALB [56,57] . A schematic illustration of immobilized CALB on organo -modifi ed clays is presented in Figure 2.2 .…”

“…A combination of techniques, such as powder X -ray diffraction ( XRD ) [56,58] , thermogravimetric analysis ( TGA ) [57] , differential thermal analysis ( DTA ) [57] , X -ray photoelectron spectroscopy ( XPS ) [56,58] , scanning electron microscopy ( SEM ) [26,57] , Fourier transform infrared ( FT -IR ) spectroscopy [57,58] and BET N 2 adsorption measurements [67] , was used for structural characterization of the enzyme -clay conjugates.…”

“…FT -IR is another tool to confi rm the successful immobilization of an enzyme on a solid support [57,58,68] . More specifi cally, the binding can be confi rmed by the FT -IR spectra of the immobilized enzyme onto various modifi ed and unmodifi ed clays, in which are presented all the characteristic bands of clays and protein [58,64,68] .…”