Enzymes supported on ordered mesoporous solids: a special case of an inorganic–organic hybrid

Abstract

The discovery in the late 1990s of ordered, high surface area silicas with pore sizes of 5 nm and above opened the way to the study of well-defined biomolecule-mesoporous silica hybrids. In particular, it has been possible to immobilize a range of small to medium size enzymes, such as proteases, lipases and peroxidases, via physisorption, encapsulation and tethering on the internal surfaces of the solids. Use has also been made of silicas functionalized for this purpose. In many cases the immobilized enzymes are both active and re-usable. Here we review the studies on enzymes immobilized on ordered mesoporous solids and assess the need for careful studies in real applications. Furthermore, we note the emerging applications of related biomolecule-mesoporous solid hybrids in other applications, such as intracellular drug delivery and transfection technology.

Covalent attachment of functional side-groups to polyaniline nanofibres

“…Amine terminated chains are interesting in that they provide a template which could be further altered to enhance the selectivity of PAni. Carboxylic acid and amine groups are excellent sites for biomolecule attachment (such as proteins and saccharides) (Lisichkin and Kudrinskii, 2007;Yiu and Wright, 2005). Therefore, by functionalising PAni nanofibres, we provide a mechanism to broaden potential applications for the material.…”

The Five Ws (and one H) of Super-Hydrophobic Surfaces in Medicine

“…The transport of a trace inside a slowly evaporating drop on a substrate and the consequent particle deposition is a complex phenomenon that has generated interest for potentials in applications, such as molecular sieves [25], optoelectronic devices [26], drug delivery [27,28] and for the absorption and separation of the low molecular weight content of human plasma [29][30][31]. Despite its complexity, to the first approximation, this mechanism can be regarded (and analyzed) as the superposition of simpler effects.…”

Modification of Mesoporous Silicates for Immobilization of Enzymes

“…Such inhomogeneous distributions can arise from diffusional and steric factors. A two-step approach to functionalising the internal surface of the channels has been described [23] in which the external surface was first modified with Ph 2 SiCl 2 followed by functionalization of the internal surface with (CH 3 O) 3 Si(CH 2 ) 3 NH 2 . An important point to note when preparing materials using this approach is that the modified material should be sufficiently stable to withstand the solvent extraction process required to remove the surfactant.…”

“…Since the publication of this work there has been a surge in interest in using these materials for a broad range of applications. In particular, their ordered pore structure together with pore diameters which are comparable in size to those of enzymes make them ideal candidates for the immobilization of enzymes [2][3][4]. Transmission electron micrographs of three representative MPS materials depicting the ordered porosity of the materials are shown in Fig.…”

“…The ideal support for immobilization of an enzyme should have a high surface area with good mechanical and chemically stability, be available at low cost and have minimal non-specific adsorption properties. MPS have been widely used as supports for enzymes in biocatalytic applications [2][3][4]. A method of preparation of MPS for use as low density silica was first described in 1969 [5].…”