Mesoporous organic-inorganic hybrid materials, a new class of materials characterized by large specific surface areas and pore sizes between 2 and 15 nm, have been obtained through the coupling of inorganic and organic components by template synthesis. The incorporation of functionalities can be achieved in three ways: by subsequent attachment of organic components onto a pure silica matrix (grafting), by simultaneous reaction of condensable inorganic silica species and silylated organic compounds (co-condensation, one-pot synthesis), and by the use of bissilylated organic precursors that lead to periodic mesoporous organosilicas (PMOs). This Review gives an overview of the preparation, properties, and potential applications of these materials in the areas of catalysis, sorption, chromatography, and the construction of systems for controlled release of active compounds, as well as molecular switches, with the main focus being on PMOs.

Silica-based mesoporous organic-inorganic hybrid materials.

Ordered mesoporous materials in catalysis

Immobilization is often the key to optimizing the operational performance of an enzyme in industrial processes, particularly for use in non-aqueous media. Different methods for the immobilization of enzymes are critically reviewed. The methods are divided into three main categories, viz. (i) binding to a prefabricated support (carrier), (ii) entrapment in organic or inorganic polymer matrices, and (iii) cross-linking of enzyme molecules. Emphasis is placed on relatively recent developments, such as the use of novel supports, e.g., mesoporous silicas, hydrogels, and smart polymers, novel entrapment methods and cross-linked enzyme aggregates (CLEAs).

http://largens.com/biochemlab/peroxidase2.pdf

Enzyme immobilization: The quest for optimum performance

The encapsulation of enzymes and other proteins into inorganic host materials has attracted considerable attention over the past few years This research has demonstrated that biomolecules immobilized in inorganic matrixes retain their functional characteristics to a large extent These new materials are of interest for applications as (optically based) biosensors and biocatalysts We review the growing field of amino acids, vitamins, enzymes, and whole cells adsorbed (immobilized) onto ordered mesoporous silica and carbon molecular sieves Strategies for the preparation of mesoporous supports and the essential properties of the resulting materials with respect to the envisaged applications are presented Basic effects of the nature of the adsorption and various aspects of the application of these materials as biosensors, bicatalysts, and for drug release are discussed Outlook of potential applications and further challenges are also provided

Ordered Mesoporous Materials for Bioadsorption and Biocatalysis

Although many methods for enzyme immobilization have been described in patents and publications, relatively few processes employing immobilized enzymes have been successfully commercialized. The cost of most industrial enzymes is often only a minor component in overall process economics, and in these instances, the additional costs associated with enzyme immobilization are often not justified. More commonly the benefit realized from enzyme immobilization relates to the process advantages that an immobilized catalyst offers, for example, enabling continuous production, improved stability and the absence of the biocatalyst in the product stream. The development and attributes of several established and emerging industrial applications for immobilized enzymes, including high-fructose corn syrup production, pectin hydrolysis, debittering of fruit juices, interesterification of food fats and oils, biodiesel production, and carbon dioxide capture are reviewed herein, highlighting factors that define the advantages of enzyme immobilization.

Industrial use of immobilized enzymes

An enzyme, horseradish peroxidase (HRP), was adsorbed in the manner of the single immersion method on the silica mesoporous materials FSM-16, MCM-41, and SBA-15 with various pore diameters from 27 to 92 A, and their enzymatic activities in an organic solvent and the thermal stabilities were studied. FSM-16 and MCM-41 showed a larger amount of adsorption of HRP than SBA-15 or silica gel when the pore sizes were larger than the 50 A. The increased enzyme adsorption capacity may be due to the surface characteristics of FSM-16 and MCM-41, which would be consistent with the observed larger adsorption capacity of cationic pigment compared with anionic pigment for these materials. The immobilized HRP on FSM-16 and MCM-41 with pore diameter 50 A showed the highest enzymatic activity in an organic toluene and thermal stability in aqueous solution at the temperature of 70 °C. The immobilized enzymes on the other mesoporous materials including large or small pore sized FSM-16 showed lower enzymatic activity in an or...

Haruo Takahashi

Papers

Catalytic Activity in Organic Solvents and Stability of Immobilized Enzymes Depend on the Pore Size and Surface Characteristics of Mesoporous Silica

Immobilized enzymes in ordered mesoporous silica materials and improvement of their stability and catalytic activity in an organic solvent