Encapsulation and Reactivity of Proteins in Optically Transparent Porous Silicate Glasses Prepared by the Sol-Gel Method

1992 ◽  
Vol 277 ◽  
Author(s):  
Stacey A. Yamanaka ◽  
Lisa M. Ellerby ◽  
Ester H. Lan ◽  
Clinton R. Nishida ◽  
Fumito Nishida ◽  
...  
Keyword(s):  
Glucose Oxidase ◽  
Sol Gel ◽  
Porous Silica ◽  
Spectroscopic Properties ◽  
Visible Absorption ◽  
Copper Zinc Superoxide Dismutase ◽  
Optically Transparent ◽  
Copper Zinc ◽  
Porous Silica Glass ◽  
Glass Matrices

ABSTRACTCopper-zinc superoxide dismutase (CuZnSOD), myoglobin, hemoglobin and glucose oxidase are encapsulated in stable, optically transparent, porous, silica glass matrices synthesized under mild conditions using novel sol-gel synthetic techniques. The biomolecules retain their characteristic reactivities and spectroscopic properties. The porous glasses allow transport of small molecules into and out of the glasses at reasonable rates but retain the protein molecules within the pores. The chemical reactions of the immobilized proteins are monitored by means of changes in their visible absorption spectra. Four encapsulated proteins are studied: CuZnSOD reacts with CN−; metmyoglobin is reduced to its deoxy form and then reacts with O2 to make the oxy form and CO to make the carbonyl form; methemoglobin is reduced to its deoxy form and reacted with CO to make the carbonyl form; and glucose oxidase is reacted with glucose to make gluconic acid.

Optical Sol-Gel Materials Based on Binding and Catalysis by Biomolecules

1994 ◽  
Vol 346 ◽  
Author(s):  
Jeffrey I. Zink ◽  
Bruce Dunn ◽  
Stacey Yamanaka ◽  
Esther Lan ◽  
J. S. Valentine ◽  
...  
Keyword(s):  
Silica Glass ◽  
Glucose Sensor ◽  
Sol Gel ◽  
Porous Silica ◽  
Spectroscopic Properties ◽  
Colored Glass ◽  
Visible Absorption ◽  
Copper Zinc Superoxide Dismutase ◽  
Immobilized Proteins ◽  
Glass Matrices

ABSTRACTThe proteins copper-zinc Superoxide dismutase (CuZnSOD), cytochrome c, myoglobin, hemoglobin, and bacterio-rhodopsin are encapsulated in stable, optically transparent, porous, silica glass matrices prepared by the sol-gel method such that the biomolecules retain their characteristic reactivities and spectroscopic properties. The resulting glasses allow transport of small molecules into and out of the glasses at reasonable rates but retain the protein molecules within their pores. The transparency of the glasses enables the chemical reactions of the immobilized proteins to be monitored by means of changes in their visible absorption spectra. Silica glasses containing the immobilized proteins have similar reactivities and spectroscopic properties to those found for the proteins in solution. The enzymes glucose oxidase and peroxidase were also encapsulated in transparent silica glass matrices. Upon exposure to glucose solutions, a colored glass is formed that can be used as the active element in a solid state optically based glucose sensor. Likewise, gels containing oxalate oxidase and peroxidase exhibit spectroscopic changes upon exposure to aqueous solutions containing oxalic acid.

scholarly journals Glucose biosensor based on entrapment of glucose oxidase and myoglobin in silica gel by the sol-gel method

2005 ◽  
Vol 19 (2) ◽  
pp. 119-126 ◽  
Author(s):  
Mohammed A. Zaitoun
Keyword(s):  
Hydrogen Peroxide ◽  
Glucose Oxidase ◽  
Glucose Concentration ◽  
Decay Curve ◽  
Sol Gel ◽  
Porous Silica ◽  
Glucose Biosensor ◽  
Negative Peak ◽  
Before And After ◽  
Porous Silica Glass

A spectrophotometric method is presented to determine glucose employing the sol-gel technique. Myoglobin (Mb) and glucose oxidase are encapsulated in a transparent and porous silica glass. The produced gel (xerogel) is then immersed in water where increments of glucose are added to the solution with stirring; glucose diffuses into the sol-gel glass pores and a series of reactions take place. Glucose is first oxidized by glucose oxidase and oxygen to gluconate and hydrogen peroxide is generated. The liberated hydrogen peroxide oxidizes the Mb heme (Fe2+into Fe3+). The higher is the glucose concentration added, the more is the H2O2generated, and the more is the Mb oxidation (Fe2+to Fe3+) and as a result the higher is the absorbance at 400 nm (negative peak, lower absorbance value). All measurements are performed at this wavelength (400 nm), the negative peak obtained by subtracting the absorption spectra of Mb before and after oxidation. Measuring the slope of the absorbance decay versus time at 400 nm monitors increments of added glucose. Each glucose concentration has an accompanying unique decay curve with a unique slope. The higher is the glucose concentration; the steeper is the decay curve (higher slope value). The calibration curve was linear up to 40 mM.

scholarly journals Silica Sol-Gel Entrapment of the Enzyme Chloroperoxidase

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Tuan Le ◽  
Selina Chan ◽  
Bassem Ebaid ◽  
Monika Sommerhalter
Keyword(s):  
Pore Diameter ◽  
Sol Gel ◽  
Porous Silica ◽  
Catalytic Performance ◽  
Relative Activity ◽  
Silica Sol ◽  
Average Pore ◽  
Visible Absorption ◽  
Gel Beads ◽  
Methanol Exposure

The enzyme chloroperoxidase (CPO) was immobilized in silica sol-gel beads prepared from tetramethoxysilane. The average pore diameter of the silica host structure (~3 nm) was smaller than the globular CPO diameter (~6 nm) and the enzyme remained entrapped after sol-gel maturation. The catalytic performance of the entrapped enzyme was assessed via the pyrogallol peroxidation reaction. Sol-gel beads loaded with 4 μg CPO per mL sol solution reached 9–12% relative activity compared to free CPO in solution. Enzyme kinetic analysis revealed a decrease inkcatbut no changes inKMorKI. Product release or enzyme damage might thus limit catalytic performance. Yet circular dichroism and visible absorption spectra of transparent CPO sol-gel sheets did not indicate enzyme damage. Activity decline due to methanol exposure was shown to be reversible in solution. To improve catalytic performance the sol-gel protocol was modified. The incorporation of 5, 20, or 40% methyltrimethoxysilane resulted in more brittle sol-gel beads but the catalytic performance increased to 14% relative to free CPO in solution. The use of more acidic casting buffers (pH 4.5 or 5.5 instead of 6.5) resulted in a more porous silica host reaching up to 18% relative activity.

One-pot sol-gel synthesis of porous silica glass with gold nanoparticles

2017 ◽  
Vol 27 (5) ◽  
pp. 531-534 ◽  
Author(s):  
Andriy P. Budnyk ◽  
Svetlana O. Cherkasova ◽  
Alessandro Damin
Keyword(s):  
Gold Nanoparticles ◽  
Silica Glass ◽  
Sol Gel ◽  
Porous Silica ◽  
One Pot ◽  
Porous Silica Glass ◽  
Sol Gel Synthesis

Copper-zinc superoxide dismutase from Ascaris suum (Nematoda): Purification and characterization

1994 ◽  
Vol 14 (2) ◽  
pp. 83-90
Author(s):  
Manuel Sanchez-Moreno ◽  
Emilio Entrala ◽  
Dirk Janssen ◽  
Antonio Osuna
Keyword(s):  
Superoxide Dismutase ◽  
Specific Activity ◽  
Ascaris Suum ◽  
Sodium Dodecyl ◽  
Storage Conditions ◽  
Visible Absorption ◽  
Copper Zinc Superoxide Dismutase ◽  
Zinc Superoxide Dismutase ◽  
Copper Zinc ◽  
Pharmacological Screening

Copper-zinc superoxide dismutase from Ascaris suum (Nematoda) was purified in a new, more efficient, and faster manner. The process included differential centrifugation, fractionation with ammonium sulfate, and sodium dodecyl sulfate-polyacrylamide electrophoresis, yielding a 340-fold purification (specific activity of 47 units/mg). Optimal storage conditions, optimal pH range, thermostability, molecular weight and ultravioltet-visible absorption spectrum of the enzyme are described, and a new enzymatic model for pharmacological screening is suggested.

Effect of Copper-Zinc Superoxide Dismutase on Endothelium-Dependent Vasodilation in Patients With Essential Hypertension

Hypertension ◽  
1995 ◽  
Vol 26 (6) ◽  
pp. 863-868 ◽  
Author(s):  
Carlos E. García ◽  
Crescence M. Kilcoyne ◽  
Carmine Cardillo ◽  
Richard O. Cannon ◽  
Arshed A. Quyyumi ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Essential Hypertension ◽  
Copper Zinc Superoxide Dismutase ◽  
Zinc Superoxide Dismutase ◽  
Copper Zinc ◽  
Effect Of Copper

scholarly journals Synthesis of N-CNT/TiO2 composites thin films: surface analysis and optoelectronic properties

2020 ◽  
Vol 183 ◽  
pp. 05002 ◽  
Author(s):  
Hamza Belkhanchi ◽  
Younes Ziat ◽  
Maryama Hammi ◽  
Charaf Laghlimi ◽  
Abdelaziz Moutcine ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Analysis ◽  
Sol Gel ◽  
Careful Analysis ◽  
Optoelectronic Properties ◽  
Spectroscopic Techniques ◽  
Large Area ◽  
Visible Absorption ◽  
Temperature Solution ◽  
Good Agreement

In this study, we have investigated the surface analysis and optoelectronic properties on the synthesis of N-CNT/TiO2 composites thin films, using sol gel method for a dye synthetized solar cell (DSSC) which is found to be simple and economical route. The titanium dioxide based solar cells are an exciting photovoltaic candidate; they are promising for the realization of large area devices. That can be synthetized by room temperature solution processing, with high photoactive performance. In the present work, we stated comparable efficiencies by directing our investigation on obtaining Sol Gel thin films based on N-CNT/TiO2, by dispersing nitrogen (N) doped carbon nanotubes (N-CNTs) powders in titanium tetraisopropoxyde (TTIP). The samples were assessed in terms of optical properties, using UV—visible absorption spectroscopic techniques. After careful analysis of the results, we have concluded that the mentioned route is good and more efficient in terms of optoelectronic properties. The gap of “the neat” 0.00w% N-CNT/TiO2 is of 3eV, which is in a good agreement with similar gap of semiconductors. The incorporated “w%NCNTs” led to diminishing the Eg with increasing N-CNTs amount. These consequences are very encouraging for optoelectronic field.

scholarly journals Development of Novel Oral Formulations of Disulfide Antioxidants Based on Porous Silica for Controlled Release of the Drugs

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 963
Author(s):  
Ekaterina S. Dolinina ◽  
Elena V. Parfenyuk
Keyword(s):  
Antioxidant Activity ◽  
Surface Chemistry ◽  
Sol Gel ◽  
Porous Silica ◽  
The Body ◽  
Oral Drug ◽  
Therapeutic Concentration ◽  
Release Process ◽  
Zero Order Kinetics ◽  
Long Time

Powerful antioxidant α-lipoic acid (LA) exhibits limited therapeutic efficiency due to its pharmacokinetic properties. Therefore, the purpose of this work was to evaluate the ability of silica-based composites of LA as well as its amide (lipoamide, LM), as new oral drug formulations, to control their release and maintain their therapeutic concentration and antioxidant activity in the body over a long time. The composites synthesized at different sol–gel synthesis pH and based on silica matrixes with various surface chemistry were investigated. The release behavior of the composites in media mimicking pH of digestive fluids (pH 1.6, 6.8, and 7.4) was revealed. The effects of chemical structure of the antioxidants, synthesis pH, surface chemistry of the silica matrixes in the composites as well as the pH of release medium on kinetic parameters of the drug release and mechanisms of the process were discussed. The comparative analysis of the obtained data allowed the determination of the most promising composites. Using these composites, modeling of the release process of the antioxidants in accordance with transit conditions of the drugs in stomach, proximal, and distal parts of small intestine and colon was carried out. The composites exhibited the release close to the zero order kinetics and maintained the therapeutic concentration of the drugs and antioxidant effect in all parts of the intestine for up to 24 h. The obtained results showed that encapsulation of LA and LM in the silica matrixes is a promising way to improve their bioavailability and antioxidant activity.

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