Composite Magnetic Particles as Carriers for Laccase fromTrametes versicolor

Chitosan-coated halloysite nanotube magnetic microspheres for carcinogenic colorectal hemorrhage and liver laceration in albino rats

Carcinogenic colorectal hemorrhage can cause severe blood loss and longitudinal ulcer, which ultimately become fatal if left untreated. The present study was aimed to formulate targeted release gemcitabine (GC)-containing magnetic microspheres (MM) of halloysite nanotubes (MHMG), chitosan (MCMG), and their combination (MHCMG). The preparation of MM by magnetism was confirmed by vibrating sample magnetometry (VSM), the molecular arrangement of NH₂, alumina, and silica groups was studied by X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS), the hollow spherical nature of the proposed MM was observed by scanning electron microscopy (SEM), functional groups were characterized by Fourier transform infrared (FTIR) spectroscopy and thermochemical modification was studied by thermogravimetric analysis (TGA). In vitro thrombus formation showed a decreasing trend of hemostatic time for MMs in the order of MHMG3 < MCMG3 < MHCMG7, which was confirmed by whole blood clotting kinetics. Interestingly, rat tail amputation and liver laceration showed 3 folds increased clotting efficiency of optimized MHCMG7 compared to that of control. In vivo histopathological studies and cell viability assays confirmed the regeneration of epithelial cells. The negligible systemic toxicity of MHCMG7, more than 90% entrapment of GC and high % release in alkaline medium made the proposed MM an excellent candidate for the control of hemorrhage in colorectal cancer. Conclusively, the healing of muscularis and improved recovery of the colon from granulomas ultimately improved the therapeutic effects of GC-containing MMs. The combination of both HNT and CTS microspheres made them more targeted.

Enhanced thermostability of the immobilized thermoalkalophilic esterase onto magnetic-cornstarch nanoparticle

The immobilization of the biocatalysts onto magnetic nanoparticles has been extensively applied as the external magnetic field facilitates the enzyme recovery from the reaction mixture. In the present study, glutaraldehyde-modified magnetite-cornstarch nanoparticles (MCNs) were successfully synthesized, elaborately characterized by ZetaSizer and surface-enhanced Raman spectroscopy, and used for the immobilization of a thermoalkalophilic esterase from Geobacillus sp. The optimal immobilization conditions were obtained at 65°C, 2:3 molar ratios of Fe²⁺ :Fe³⁺ , and 1 g cornstarch resulted in approximately 90 nm magnetic particles in size. Also, immobilization yield and immobilization efficiency of the esterase were found as 74% and 82%, respectively. Scanning electron microscopy micrographs showed that MCNs were uniform, spherical in shape, and well dispersed and esterase immobilized MCNs displayed similar morphology as free MCNs. The maximum activity of free and immobilized esterase was obtained at 65°C and pH 9. Immobilization onto glutaraldehyde-modified MCNs significantly enhanced the esterase thermostability. Additionally, the immobilized esterase kept its residual activity of 75% after three sequential cycles, suggesting that it has favorable operational stability.

Balancing Enzyme Encapsulation Efficiency and Stability in Complex Coacervate Core Micelles

Encapsulation of charged proteins into complex coacervate core micelles (C3Ms) can be accomplished by mixing them with oppositely charged diblock copolymers. However, these micelles tend to disintegrate at high ionic strength. Previous research showed that the addition of a homopolymer with the same charge sign as the protein improved the stability of protein-containing C3Ms. In this research, we used fluorescence correlation spectroscopy (FCS) and dynamic light scattering (DLS) to study how the addition of the homopolymer affects the encapsulation efficiency and salt stability of the micelles. We studied the encapsulation of laccase spore coat protein A (CotA), a multicopper oxidase, using a strong cationic-neutral diblock copolymer, poly(N-methyl-2-vinyl-pyridinium iodide)-block-poly(ethylene oxide) (PM2VP128-b-PEO477), and a negatively charged homopolymer, poly(4-styrenesulfonate) (PSS215). DLS indeed showed an improved stability of this three-component C3M system against the addition of salt compared to a two-component system. Remarkably, FCS showed that the release of CotA from a three-component C3M system occurred at a lower salt concentration and over a narrower concentration range than the dissociation of C3Ms. In conclusion, although the addition of the homopolymer to the system leads to micelles with a higher salt stability, CotA is excluded from the C3Ms already at lower ionic strengths because the homopolymer acts as a competitor of the enzyme for encapsulation.

A catechol biosensor based on immobilizing laccase to Fe3O4@Au core-shell nanoparticles

This work is directed towards the synthesis of the magnetic nanoparticle in a core and a gold shell with immobilized of laccase on its surface (Fe₃O₄@Au@ Lac). The prepared Fe₃O₄@Au@ Lac core/shell nanoparticles are characterized by means TEM, SEM, DLS, zeta potential, UV-Vis, and TGA. Meanwhile, as an example of the applications, Biosensor activity was investigated by using the oxidation of catechol and recording the UV-Vis absorption in the 402 nm wavelength. The biosensor also demonstrated optimum activity at pH 5.0, reaction time at 40 min, and 35 mg the amount of biosensor. Linear response in the catechol concentration range of 5.0-70.0 μM. The limit of detection and the apparent Michaels-Menten constant (K_m) of the biosensor were 2 μM and 15 μM respectively.

Synthesis and Assembly of Laccase-Polymer Giant Amphiphiles by Self-Catalyzed CuAAC Click Chemistry

Covalent coupling of hydrophobic polymers to the exterior of hydrophilic proteins would mediate unique macroscopic assembly of bioconjugates to generate amphiphilic superstructures as novel nanoreactors or biocompatible drug delivery systems. The main objective of this study was to develop a novel strategy for the synthesis of protein-polymer giant amphiphiles by the combination of copper-mediated living radical polymerization and azide-alkyne cycloaddition reaction (CuAAC). Azide-functionalized succinimidyl ester was first synthesized for the facile introduction of azide groups to proteins such as albumin from bovine serum (BSA) and laccase from Trametes versicolor. Alkyne-terminal polymers with varied hydrophobicity were synthesized by using commercial copper wire as the activators from a trimethylsilyl protected alkyne-functionalized initiator in DMSO under ambient temperature. The conjugation of alkyne-functionalized polymers to the azide-functionalized laccase could be conducted even without additional copper catalyst, which indicated a successful self-catalyzed CuAAC reaction. The synthesized amphiphiles were found to aggregate into spherical nanoparticles in water and showed strong relevance to the hydrophobicity of coupled polymers. The giant amphiphiles showed decreased enzyme activity yet better stability during storage after chemical modification and self-assembly. These findings will deepen our understanding on protein folding, macroscopic self-assembly, and support potential applications in bionanoreactor, enzyme immobilization, and water purification.

Eco-Friendly Composite of Fe3O4-Reduced Graphene Oxide Particles for Efficient Enzyme Immobilization

A novel type of spherical and porous composites were synthesized to dually benefit from reduced graphene oxide (rGO) and magnetic materials as supports for enzyme immobilization. Three magnetic composite particles of Fe₃O₄ and rGO containing 71% (rGO-Fe₃O₄-M1), 36% (rGO-Fe₃O₄-M2), and 18% (rGO-Fe₃O₄-M3) Fe were prepared using a one-pot spray pyrolysis method and were used for the immobilization of the model enzymes, laccase and horseradish peroxidase (HRP). The rGO-Fe₃O₄ composite particles prepared by spray pyrolysis process had a regular shape, finite size, and uniform composition. The immobilization of laccase and HRP on rGO-Fe₃O₄-M1 resulted in 112 and 89.8% immobilization efficiency higher than that of synthesized pure Fe₃O₄ and rGO particles, respectively. The stability of laccase was improved by approximately 15-fold at 25 °C. Furthermore, rGO-Fe₃O₄-M1-immobilized laccase exhibited 92.6% of residual activity after 10 cycles of reuse and was 192% more efficient in oxidizing different phenolic compounds than the free enzyme. Therefore, these unique composite particles containing rGO and Fe₃O₄ may be promising supports for the efficient immobilization of industrially important enzymes with lower acute toxicity toward Vibrio fischeri than commercial pure Fe₃O₄ particles.

Large-scale aerosol-assisted synthesis of biofriendly Fe₂O₃ yolk-shell particles: a promising support for enzyme immobilization

Multiple-shelled Fe2O3 yolk-shell particles were synthesized using the spray drying method and intended as a suitable support for the immobilization of commercial enzymes such as glucose oxidase (GOx), horseradish peroxidase (HRP), and laccase as model enzymes. Yolk-shell particles have an average diameter of 1-3 μm with pore diameters in the range of 16 to 28 nm. The maximum immobilization of GOx, HRP, and laccase resulted in the enzyme loading of 292, 307 and 398 mg per g of support, respectively. After cross-linking of immobilized laccase by glutaraldehyde, immobilization efficiency was improved from 83.5% to 90.2%. K(m) and V(max) values were 41.5 μM and 1722 μmol min(-1) per mg protein for cross-linked laccase and those for free laccase were 29.3 μM and 1890 μmol min(-1) per mg protein, respectively. The thermal stability of the enzyme was enhanced up to 18-fold upon cross-linking, and the enzyme retained 93.1% of residual activity after ten cycles of reuse. The immobilized enzyme has shown up to 32-fold higher stability than the free enzyme towards different solvents and it showed higher efficiency than free laccase in the decolorization of dyes and degradation of bisphenol A. The synthesized yolk-shell particles have 3-fold higher enzyme loading efficiency and lower acute toxicity than the commercial Fe2O3 spherical particles. Therefore, the use of unique yolk-shell structure Fe2O3 particles with multiple-shells will be promising for the immobilization of various enzymes in biotechnological applications with improved electrochemical properties. To the best of our knowledge, this is the first report on the use of one pot synthesized Fe2O3 yolk-shell structure particles for the immobilization of enzymes.

Polymer functionalized magnetic nanoconstructs for immunomagnetic separation of analytes

Core–shell polymer functionalized magnetic nanoparticles are promising material for rapid immunomagnetic separation and detection of analyte.

Novel functionalized fluorescent polymeric nanoparticles for immobilization of biomolecules

Novel, size controlled fluorescent polymeric nanoparticles (FPNP) were synthesized having acetoacetoxy functionality on the surface for immobilization of biomolecules which can be utilized as biomarkers and labels in fluoroimmunoassays. Core-shell nanoparticles of poly(styrene, St-methyl methacrylate, MMA-acetoacetoxy ethyl methacrylate, AAEM), stabilized by various concentrations of surfactant, sodium lauryl sulphate (SLS), were obtained by facile miniemulsion co-polymerization encapsulated with pyrene molecules in their hydrophobic core. Analytical, spectroscopic and imaging characterization techniques revealed the formation of stable, monodisperse, spherical nano sized particles exhibiting high luminescence properties. Particles with 1% SLS (S1) showed good dispersion stability and fluorescence intensity and were chosen as ideal candidates for further immobilization studies. Steady state fluorescence studies showed 10 times higher fluorescence intensity of S1 nanoparticles than that of pyrene solution in solvent-toluene at the same concentration. Environmental factors such as pH, ionic strength and time were found to have no effect on fluorescence intensity of FPNPs. Surface β-di-ketone groups were utilized for the covalent immobilization of enzyme conjugated antibodies without any activation or pre-treatment of nanoparticles.

Simple fabrication of polymer-based Trametes versicolor laccase for decolorization of malachite green

A highly efficient and stable biocatalyst (denoted D201_Lac) was fabricated by encapsulating Trametes versicolor laccase within a macroporous and strongly basic exchange resin D201 through a simple adsorption process. Transmission electron micrographs and Fourier transform infrared spectra of the resultant D201_Lac proved that nanosized laccase clusters were embedded into the inner nano-pores/channels of D201. As compared to the free laccase, D201_Lac showed enhanced resistance in the pH range of 3-7 or at temperature of 30-60°C. Besides, negligible laccase was leached out from the host polymer D201 in solution of pH 3-7 and NaCl concentration up to 0.5M, which might be attributed to the electrostatic attraction and the possible twining between long-chain laccase and the cross-linking host resin. Continuous seven-cycle batch decoloration of malachite green demonstrates that decoloration efficiency of D201_Lac kept constant for more than 320-h operation.

Dielectric properties tangential to the interface in model insoluble monolayers: theoretical assessment

Studies of insoluble monolayers built of phospholipids and various long-chained fatty acids or their glycerin esters are the major source for what is currently known about the relationship between monolayer composition and physicochemical properties. The surface pressure, dipole moment, dielectric permittivity, polarizability, refractivity, and other electrical and optical features are governed by the surfactant structural specificity and solvent organization at the microscopic level. To provide insight into the atomistic details of the interfacial structure, model monolayers at the air/water interface of two distinctly different in composition and isotherm profile surfactants are investigated by means of molecular dynamics all-atom simulations. Analysis of the computational results allows the estimation of empirically unattainable quantities such as tangential (di)electric properties, their decomposition to surfactant and water contributions, and their relationship with the changes in interfacial molecular organization at different surface concentrations. The employed theoretical approach provides a comprehensive description of interfacial phenomena at the molecular level where the traditional phenomenological investigations are ineffective.

Enhanced bioremediation of polycyclic aromatic hydrocarbons by environmentally friendly techniques

Polycyclic aromatic hydrocarbons (PAHs) are recognized as a worldwide environmental contamination problem because of their intrinsic chemical stability, high resistance to various transformation processes, and toxicity property. Because of the wide distribution of the PAHs in the environment, human exposure to the PAHs is likely to occur from dermal contact, ingestion of particles, inhalation of airborne dust, or bioaccumulation in the food chains. Therefore, their remediation is considered indispensable for environmental clean up and human health. The objective of this article is to provide a quick review on toxicity of PAHs, biodegradation of PAHs, influence of selected environmental factors on PAHs biodegradation, selected techniques for enhancing biodegradation of PAHs, and a detailed description of two environmentally friendly techniques used in our laboratory for PAHs enhanced bioremediation. Finally, an overview on the green chemistry concept and its relevance to development of several environmental fingerprinting tools for predicting successful PAHs detoxification are discussed.