Immobilization of lipase from Candida rugosa on Sepabeads(®): the effect of lipase oxidation by periodates.

The objective of this paper was the investigation of a suitable Sepabeads(®) support and method for immobilization of lipase from Candida rugosa. Three different supports were used, two with amino groups, (Sepabeads(®) EC-EA and Sepabeads(®) EC-HA), differing in spacer length (two and six carbons, respectively) and one with epoxy group (Sepabeads(®) EC-EP). Lipase immobilization was carried out by two conventional methods (via epoxy groups and via glutaraldehyde), and with periodate method for modification of lipase. The results of activity assays showed that lipase retained 94.8% or 87.6% of activity after immobilization via epoxy groups or with periodate method, respectively, while glutaraldehyde method was inferior with only 12.7% of retention. The immobilization of lipase, previously modified by periodate oxidation, via amino groups has proven to be more efficient than direct immobilization of lipase via epoxy groups. In such a way immobilized enzyme exhibited higher activity at high reaction temperatures and higher thermal stability.

New Advances in Fabrication of Graphene Glyconanomaterials for Application in Therapy and Diagnosis.

Glycoderivatives are an important class of molecules with enormous relevance in numerous biological phenomena; therefore, they have a key role in the learning, understanding, and assessment of different diseases. Nanotechnology, and in particular the design of new nanomaterials, is one of the areas of greatest interest today. In this case, graphene nanomaterials represent very interesting platforms for studying glycosystems, glyconanomaterials that combine the biomolecular recognition and the characteristics of nanoscale objects in the development of early diagnosis systems, and efficient specific therapeutic modalities. In this mini-review, we discuss some results recently described in the literature on the conjugation of graphene materials and carbohydrates through the selective interaction of glycoenzymes in graphene to create new materials with biosensing applications, the development and application of sugar-graphene composites, and finally biosystems combining the properties of graphene with metallic nanoparticles and sugars for the creation of excellent glyconanomaterials as novel systems for the therapy or diagnosis of important diseases such as cancer or diabetes.

Immobilization of dextransucrase on functionalized TiO2 supports.

The TiO2 based hybrid supports with different functional groups (amino, glutaraldehyde or epoxy) were prepared and their influence on immobilization of dextransucrase (DS) was studied. Novel synthetic route for surface modification of TiO2 with amino and glutaraldehyde groups was developed taking advantage of charge transfer complex (CTC) formation between surface Ti atoms and salicylate-type of ligand (5­aminosalicylic acid (5-ASA)). The proposed coordination of 5-ASA to the surface of TiO2 powder and optical properties of CTC was presented. The pristine TiO2 and amino functionalized TiO2 have higher sorption capacity for DS (12.6 and 12.0mgg-1, respectively) compared to glutaraldehyde and epoxy activated supports (9.6 and 9.8mgg-1, respectively). However, immobilized enzyme to either glutaraldehyde or epoxy functionalized TiO2 have almost two times higher expressed activities compared to pristine TiO2 support (258, 235 and 142IUg-1, respectively). Thermal stability of enzyme immobilized on glutaraldehyde and epoxy functionalized supports was studied at 40°C, as well as operational stability under long-run working conditions in repeated cycles. After five cycles, DS imobilized on glutaraldehyde activated support retained almost 70% of its initial expressed activity, while, after five cycles, performance of DS immobilized on epoxy activated support was significantly lower (15%).

Covalent Immobilization of Enzymes on Eupergit® Supports: Effect of the Immobilization Protocol.

A selection of best combination of adequate immobilization support and efficient immobilization method is still a key requirement for successful application of immobilized enzymes on an industrial level. Eupergit® supports exhibit good mechanical and chemical properties and allow establishment of satisfactory hydrodynamic regime in enzyme reactors. This is advantageous for their wide application in enzyme immobilization after finding the most favorable immobilization method. Methods for enzyme immobilization that have been previously reported as efficient considering the obtained activity of immobilized enzyme are presented: direct binding to polymers via their epoxy groups, binding to polymers via a spacer made from ethylene diamine/glutaraldehyde, and coupling the periodate-oxidized sugar moieties of the enzymes to the polymer beads. The modification of the conventionally immobilized enzyme with ethylenediamine via the carbodiimide route seems to be a powerful tool to improve its stability and catalytic activity.

Synthesis of aliphatic esters of cinnamic acid as potential lipophilic antioxidants catalyzed by lipase B from Candida antarctica.

Immobilized lipase from Candida antarctica (Novozyme 435) was tested for the synthesis of various phenolic acid esters (ethyl and n-butyl cinnamate, ethyl p-coumarate and n-butyl p-methoxycinnamate). The second-order kinetic model was used to mathematically describe the reaction kinetics and to compare present processes quantitatively. It was found that the model agreed well with the experimental data. Further, the effect of alcohol type on the esterification of cinnamic acid was investigated. The immobilized lipase showed more ability to catalyze the synthesis of butyl cinnamate. Therefore, the process was optimized for the synthesis of butyl cinnamate as a function of solvent polarity (logP) and amount of biocatalyst. The highest ester yield of 60.7 % was obtained for the highest enzyme concentration tested (3 % w/w), but the productivity was for 34 % lower than the corresponding value obtained for the enzyme concentration of 1 % (w/w). The synthesized esters were purified, identified, and screened for antioxidant activities. Both DPPH assay and cyclic voltammetry measurement have shown that cinnamic acid esters have better antioxidant properties than cinnamic acid itself.

The immobilization of enzyme on Eupergit® supports by covalent attachment.

A selection of the best combination of adequate immobilization support and efficient immobilization method is still a key requirement for successful application of immobilized enzymes on the industrial level. Eupergit) supports exhibit good mechanical and chemical properties and allow establishment of satisfactory hydrodynamic regime in enzyme reactors. This is a good recommendation for their wide application in enzyme immobilization after finding the most favorable immobilization method. Methods for enzyme immobilization that have been previously reported as efficient, considering the obtained activity of immobilized enzyme are presented: direct binding to polymers via their epoxy groups, binding to polymers via a spacer made from ethylene diamine/glutaraldehyde, and coupling the periodate-oxidized sugar moieties of the enzymes to the polymer beads.

Use of Candida rugosa lipase immobilized on sepabeads for the amyl caprylate synthesis: batch and fluidized bed reactor study

Lipase from Candida rugosa was covalently immobilized on Sepabeads EC-EP for application for amyl caprylate synthesis in an organic solvent system. Several solvents were tested in terms of biocatalyst stability and the best result was obtained with isooctane. The lipase-catalyzed esterification in the selected system was performed in batch and fluidized bed reactor systems. The influence of several important reaction parameters including temperature, initial water content, enzyme loading, acid/alcohol molar ratio, and time of addition of molecular sieves is carefully analyzed by means of an experimental design. Almost complete conversion (> 99 percent) of the substrate to ester could be performed in a batch reactor system, using lipase loading as low as 37 mg g-1 dry support and in a relatively short time (24 hrs) at 37°C, when high initial substrate molar ratio of 2.2 is used. Kinetics in a fluidized bed reactor system seems to still have a slightly better profile than in the batch system (90.2 percent yields after 14 hrs). The fluidized bed reactor operated for up 70 hrs almost with no loss in productivity, implying that the proposed process and the immobilized system could provide a promising approach for the amyl caprylate synthesis at the industrial scale.