Superparamagnetic nanoparticles as versatile carriers and supporting materials for enzymes

A hierarchical assembly of flower-like hybrid Turkish black radish peroxidase-Cu2+ nanobiocatalyst and its effective use in dye decolorization

Effective dye decolorization in wastewater still shows a big challenge. Although the biological methods, especially using enzymes, offer alternative and effective process for dye degradation and overcome the limitations of chemical and physical methods such as the instability, lack of reusability and high cost of free enzymes strictly, which limit their use in many scientific and technical applications. Enzymes rapidly lose their activities in aqueous solutions and against environmental changes due to their very susceptibility and unfavorable conformations. Herein, we report preparation of the enzyme-inorganic hybrid nanostructures with flower-like shape consisting of Turkish black radish peroxidase and Cu²⁺ metal ions using an encouraging enzyme immobilization approach. The peroxidase-Cu²⁺ hybrid nanoflowers (NFs) exhibited enhanced stability and activity towards various pH values and provided excellent dye decolorization efficiency for Victoria blue (VB) dye with more than 90% within 1 h. The NFs were also repeatedly used in efficient and caused 77% VB decolorization efficiency even at tenth cycles. However, to the best of our knowledge, for the first time, we prepared peroxidase enzyme isolated from Turkish black radish incorporated NFs and used them for dye decolorization. We believe that the NFs can be promising materials for dye decolorization in real wastewater treatment.

Evaluation of immobilized hFMO3 on magnetic nanoparticles by capillary zone electrophoresis

Aim: In this paper, we developed a method to immobilize human flavin-containing monooxygenase-3 (hFMO3) using glutaraldehyde as a cross-linker onto amino-functionalized magnetic nanoparticles. Materials & methods: All the analyses were done using capillary electrophoresis coupled with a diode array detector using clozapine as a substrate. Results: The apparent Km with clozapine as substrate and inhibition of hFMO3 by methimazole were explored for immobilized hFMO3 and were found to be comparable to literature values. The immobilized enzyme could be used three-times continuously at 37°C with no loss in enzyme activity. Conclusion: A method to immobilize hFMO3 on magnetic nanoparticles has been described and evaluated in terms of enzyme activity, inhibition, pH stability and reusability.

Toxic Effects of Engineered Nanoparticles on Living Cells

Measuring toxic effects of engineered nanoparticles on living cells would require a deep understanding of themselves by the mean of their composition, physical and chemical properties and exposure concentrations. Actually, high exposure concentrations are needed to generate quantifiable effects and to perceive accumulation above background. This chapter presents an overview on the assessment about the toxic effects of engineered nanoparticles on living cells. It consists of three main sections starting with a brief introduction, the current state of engineered nanoparticles in the environment, physical and chemical properties of some important engineered nanoparticles such as “Ag, Au, ZnO, TiO2” and the target organ toxicity of the engineered nanoparticles in several biological organisms.

l-aspartate oxidase magnetic nanoparticles: synthesis, characterization and l-aspartate bioconversion

l-aspartate oxidase (LASPO) catalyses the stereospecific oxidative deamination of l-aspartate. Here, we describe the efficient immobilization of this enzyme on Fe₃O₄ NPs resulting in a stable NP-LASPO dispersion with a good reusability.

USPIO assisting degradation of MXC by host/guest-type immobilized laccase in AOT reverse micelle system

The laccase and ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) have been assembled inside the tubular mesoporous silica via co-adsorption technology to prepare host/guest-type immobilized laccase, which is applied to degrade methoxychlor (MXC) in aqueous and reverse micelle environments. The effects of various parameters on degradation of MXC were studied. Under the optimum conditions, the degradation rate could reach maximum value of 45.6 % and remain at 20.8 % after seven cycles. Moreover, the addition of small molecular compound 2, 2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) to the system could greatly improve the degradation efficiency. The MXC degradation process is a first-order reaction, and the activation energy of MXC degradation catalyzed by immobilized laccase (41.46 kJ mol(-1)) is relatively lower than that catalyzed by free laccase (44.91 kJ mol(-1)). Based on the degradation products measured by gas chromatograph-mass spectrometer (GC-MS) and nuclear magnetic resonance (NMR), the degradation mechanism of MXC has also been proposed.

Bovine glutamate dehydrogenase immobilization on magnetic nanoparticles: conformational changes and catalysis

Glutamate dehydrogenase (GDH) was immobilized on different supports and systematically investigated in order to provide a better understanding of the immobilization effects on the catalysis of multimeric enzymes.

Nanomaterials for biocatalyst immobilization – state of the art and future trends

Advantages, drawbacks and trends in nanomaterials for enzyme immobilization.

Transformable nanostructures of cholesteryl-containing rhomboidal metallacycles through hierarchical self-assembly

Various interesting nanostructures such as flowers and tadpole shaped structures were successfully obtained from well-defined cholesteryl-containing rhomboidal metallacycles prepared by coordination-driven self-assembly.

Pectinases immobilization on magnetic nanoparticles and their anti-fouling performance in a biocatalytic membrane reactor

Reversible enzyme immobilization on membrane using magneto-responsive bionanocomposites, magneto-responsive mixed matrix membrane and an external magnetic field for in situ membrane biocatalysis.

Role of functionalization: strategies to explore potential nano-bio applications of magnetic nanoparticles

Strategies to bridge the gap between magnetic nanoparticles for their nano bio applications.

Biocatalysis and biotransformation in Brazil: An overview

This review presents the recent research in biocatalysis and biotransformation in Brazil. Several substrates were biotransformed by fungi, bacteria and plants. Biocatalytic deracemization of secondary alcohols, oxidation of sulfides, sp(3) CH hydroxylation and epoxidation of alkenes were described. Chemo-enzymatic resolution of racemic alcohols and amines were carried out with lipases using several substrates containing heteroatoms such as silicon, boron, selenium and tellurium. Biotransformation of nitriles by marine fungi, hydrolysis of epoxides by microorganisms of Brazilian origin and biooxidation of natural products were described. Enzymatic reactions under microwave irradiation, continuous flow, and enzymatic assays using fluorescent probes were reported.

Nanodevices for the immobilization of therapeutic enzymes

Therapeutic enzymes are one of the most promising applications of this century in the field of pharmaceutics. Biocatalyst properties can be improved by enzyme immobilization on nano-objects, thereby increasing stability and reusability and also enhancing the targeting to specific tissues and cells. Therapeutic biocatalyst-nanodevice complexes will provide new tools for the diagnosis and treatment of old and newly emerging pathologies. Among the advantages of this approach are the wide span and diverse range of possible materials and biocatalysts that promise to make the matrix-enzyme combination a unique modality for therapeutic delivery. This review focuses on the most significant techniques and nanomaterials used for enzyme immobilization such as metallic superparamagnetic, silica, and polymeric and single-enzyme nanoparticles. Finally, a review of the application of these nanodevices to different pathologies and modes of administration is presented. In short, since therapeutic enzymes constitute a highly promising alternative for treating a variety of pathologies more effectively, this review is aimed at providing the comprehensive summary needed to understand and improve this burgeoning area.

A green route for the synthesis of a bitter-taste dipeptide combining biocatalysis, heterogeneous metal catalysis and magnetic nanoparticles

The combo protease-metal catalyst-magnetic nanoparticles was used to establish a green alternative synthetic route to produce the bitter taste dipeptide Ala-Phe.

Association of Pseudomonas putida formaldehyde dehydrogenase with superparamagnetic nanoparticles: an effective way of improving the enzyme stability, performance and recycling

The association of formaldehyde dehydrogenase fromPseudomonas putida(FalDH) with two different magnetic nanoparticles led to distinct enzyme responses depending upon the chemical modification process applied.

Synthesis of copper ion incorporated horseradish peroxidase-based hybrid nanoflowers for enhanced catalytic activity and stability

Hybrid nanoflowers (hNFs) consisting of horseradish peroxidase (HRP) enzyme and copper ions (Cu²⁺) with dramatically enhanced catalytic activity and stability.

Magnetic Cross-Linked Enzyme Aggregates (mCLEAs) of Candida antarctica lipase: an efficient and stable biocatalyst for biodiesel synthesis

Enzyme-catalyzed production of biodiesel is the object of extensive research due to the global shortage of fossil fuels and increased environmental concerns. Herein we report the preparation and main characteristics of a novel biocatalyst consisting of Cross-Linked Enzyme Aggregates (CLEAs) of Candida antarctica lipase B (CALB) which are covalently bound to magnetic nanoparticles, and tackle its use for the synthesis of biodiesel from non-edible vegetable and waste frying oils. For this purpose, insolubilized CALB was covalently cross-linked to magnetic nanoparticles of magnetite which the surface was functionalized with -NH2 groups. The resulting biocatalyst combines the relevant catalytic properties of CLEAs (as great stability and feasibility for their reutilization) and the magnetic character, and thus the final product (mCLEAs) are superparamagnetic particles of a robust catalyst which is more stable than the free enzyme, easily recoverable from the reaction medium and reusable for new catalytic cycles. We have studied the main properties of this biocatalyst and we have assessed its utility to catalyze transesterification reactions to obtain biodiesel from non-edible vegetable oils including unrefined soybean, jatropha and cameline, as well as waste frying oil. Using 1% mCLEAs (w/w of oil) conversions near 80% were routinely obtained at 30°C after 24 h of reaction, this value rising to 92% after 72 h. Moreover, the magnetic biocatalyst can be easily recovered from the reaction mixture and reused for at least ten consecutive cycles of 24 h without apparent loss of activity. The obtained results suggest that mCLEAs prepared from CALB can become a powerful biocatalyst for application at industrial scale with better performance than those currently available.

Immobilization of horseradish peroxidase on NH2-modified magnetic Fe3O4/SiO2 particles and its application in removal of 2,4-dichlorophenol

Fe₃O₄ nanoparticles were prepared by a co-precipitation method with the assistance of ultrasound irradiation, and then coated with silica generated by hydrolysis and condensation of tetraethoxysilane. The silica-coated Fe₃O₄ nanoparticles were further modified with 3-aminopropyltriethoxysilane, resulting in anchoring of primary amine groups on the surface of the particles. Horseradish peroxidase (HRP) was then immobilized on the magnetic core-shell particles by using glutaraldehyde as a crosslinking agent. Immobilization conditions were optimized to obtain the highest relative activity of the immobilized enzyme. It was found the durability of the immobilized enzyme to heating and pH variation were improved in comparison with free HRP. The apparent Michaelis constants of the immobilized HRP and free HRP with substrate were compared, showing that the enzyme activity of the immobilized HRP was close to that of free HRP. The HRP immobilized particles, as an enzyme catalyst, were used to activate H₂O₂ for degrading 2,4-dichlorophenol. The rapid degradation of 2,4-dichlorophenol indicated that the immobilized enzyme has potential applications for removing organic pollutants.

Magnetic cross-linked laccase aggregates--bioremediation tool for decolorization of distinct classes of recalcitrant dyes

The increasing use of laccase in waste water industries is useful to explore the high benefit/cost ratio of insolubilization technologies like cross linked enzyme aggregates (CLEAs) for the decolorization and detoxification of distinctive classes of recalcitrant dyes. Amino-functionalized magnetic nanoparticles bonded to CLEAs increased the potential of laccase-based CLEAs and are applicable for commercial implementation of this technology in environmental applications. The activity recovery obtained from the stable rigid structure of magnetic CLEAs was around 32%. High volumetric activity, increased in thermal and operational stability of laccase and its resistance to extreme conditions were the properties provided by these magnetic CLEAs. Kinetic studies show that the catalytic efficiency of the enzyme, based on the kcat/km value, changed significantly upon CLEAs and magnetic CLEA formations. When 0.2U/mL of magnetic CLEAs was used, the biocatalyst rapidly decolorized 61-96% of remazol brilliant blue R, malachite green and reactive black 5 initially at 50mgL(-1) at 20°C and pH7.0. Investigation of dye degradation using both active and heat denatured CLEAs revealed a slight adsorption of dyes on inactivated biocatalysts. A laboratory scale perfusion basket reactor (BR) was used to study the continuous decolorization of dyes. The efficient decolorization (>90%) of remazol brilliant blue R and slight decrease in CLEA activity were measured over a 10h period of continuous operation, which illustrates the potential of CLEAs for the wastewater treatment. The present findings will advance the understanding of dye decolorization mechanism by CLEA laccase, which could provide useful references for developing industrial wastewater treatment.