scholarly journals Thermo-responsive super porous p(NIPAM) cryogels affords enhanced thermal stability and activity for ɑ-Glucosidase enzyme by entrapping in situ

2021 ◽  
Author(s):  
Sahin Demirci ◽  
Nurettin Sahiner
Keyword(s):  
Enzyme Immobilization ◽  
Storage Stability ◽  
Storage Conditions ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Enzyme Functionality ◽  
And Storage ◽  
Enzyme Entrapment ◽  
Temperature Storage

The concept of using a thermo-responsive p(NIPAM) polymer matrix for enzyme immobilization with lower critical solution temperature (LCST) value is rationalized by availability of the compartmental milieu to enzymes to operate within super porous 3-D matrix with special environmental conditions. Therefore, the enzyme immobilization within a support material will be carried out under the storage conditions of enzymes, generally ~-20 oC to afford unnecessarily loss of enzyme functionality in comparison to the other enzyme entrapment methods. Thus, here ɑ-Glucosidase as a model enzyme was entrapped within thermo-responsive super porous p(NIPAM) cryogels (ɑ-Glu@p(NIPAM) during the synthesis that uses cryogenic condition, ~-20 oC. The LSCT value for the prepared p(NIPAM) based cryogels were determined as 34.6±1.2 oC. The immobilization yield, immobilization efficiency, and activity recovery% values were calculated as 89.4±3.1, 66.2±3.3, and 74.0±3.3%, respectively at pH 6.8 and 37 oC for ɑ-Glu@p(NIPAM) cryogel system. Interestingly, the optimum working conditions were achieved as 25 oC and pH 6.8 with higher activity, 98.4±0.2% for the prepared ɑ-Glu@p(NIPAM) cryogel system. The operational and storage stability studies revealed that the prepared ɑ-Glu@p(NIPAM) cryogel system possessed much better operational and storage stability than free ɑ-Glu enzyme e.g., more than 50% activity after 10th usage and 10-day room temperature storage time. Moreover, the kinetic parameters such as Km and Vmax of free-Glu enzyme and ɑ-Glu@p(NIPAM) cryogel system were calculated by non-linear Michaelis-Menten equation.

Immobilization of urease in poly(1-vinyl imidazole)/poly(acrylic acid) network

2010 ◽  
Vol 64 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Mehmet Şenel ◽  
Agah Coşkun ◽  
M. Fatih Abasıyanık ◽  
Ayhan Bozkurt
Keyword(s):  
Acrylic Acid ◽  
Enzyme Immobilization ◽  
Storage Stability ◽  
Polymer Network ◽  
Ft Ir ◽  
Basic Characteristics ◽  
And Storage ◽  
Menten Constant ◽  
Ft Ir Spectroscopy ◽  
Poly Acrylic Acid

AbstractIn this study, urease was immobilized in a polymer network obtained by complexation of poly(1-vinyl imidazole) (PVI) with poly(acrylic acid) (PAA). Preparation of the polymer network was monitored by FT-IR spectroscopy. Scanning electron microscopy (SEM) revealed that enzyme immobilization had a strong effect on film morphology. Proton conductivity of the PVI/PAA network was measured via impedance spectroscopy under humidified conditions. Values of the Michaelis-Menten constant (K M) for immobilized urease were higher than for the free enzyme, indicating a decreased affinity of the enzyme to its substrate. The basic characteristics (pHopt, pHstability, T opt, T stability, reusability, and storage stability) of immobilized urease were determined. The results show that the PAA/PVI polymer network is suitable for enzyme immobilization.

scholarly journals Bentonite-supported catalase

2005 ◽  
Vol 70 (5) ◽  
pp. 721-726 ◽  
Author(s):  
S. Alkan ◽  
H. Ceylan ◽  
O. Arslan
Keyword(s):  
Ionic Strength ◽  
Kinetic Parameters ◽  
Enzyme Immobilization ◽  
Storage Stability ◽  
High Ionic Strength ◽  
Enzyme Inactivation ◽  
Valuable Method ◽  
And Storage

The properties of the clay bentonite as a support for enzyme immobilization were studied using the enzyme catalase. Such an immobilization does not result in enzyme inactivation and constitutes a valuable method for immobilizing catalase at high ionic strength. The bentonite-supported catalase was characterized in terms of pH and ionic strength dependencies, thermal and storage stability and kinetic parameters. These studies indicate that bentonite is a valuable support for the simple adsorption of enzymes. .

Phase-separation immunoassays.

1987 ◽  
Vol 33 (9) ◽  
pp. 1509-1516 ◽  
Author(s):  
K Auditore-Hargreaves ◽  
R L Houghton ◽  
N Monji ◽  
J H Priest ◽  
A S Hoffman ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Solid Phase ◽  
Specific Binding ◽  
Hepatitis B Surface Antigen ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Binding Reaction ◽  
Insoluble Polymer ◽  
Capture Antibody

Abstract Solid-phase-based immunoassays have traditionally been plagued by nonspecific binding to the solid phase and by slow reaction kinetics relative to reactants that are free to diffuse in solution. We have developed two novel immunoassays in which the solid phase is generated in situ after the specific binding reaction has occurred, thereby enhancing reaction kinetics and minimizing the opportunities for non-specific binding. In the first system, the capture antibody is conjugated to an organic monomer, polymerization of which to form insoluble polymer particles is initiated by a reaction involving free radicals. The amount of signal-labeled antibody incorporated into the resulting particles is directly proportional to the concentration of antigen. The principle is illustrated for the simultaneous assay of IgG and IgM in a single sample. In the second system, capture antibody is conjugated to a polymer, the solubility of which is a function of temperature. Specific binding is conducted below the critical solution temperature of the polymer, which is then separated from solution by increasing the temperature above the critical temperature. The incorporation of signal-labeled antibody into the precipitated polymer is directly proportional to the concentration of antigen. This principle is illustrated for the assay of hepatitis B surface antigen and Chlamydia trachomatis.

scholarly journals Thermo-Reversible Gelation of Aqueous Hydrazine for Safe Storage of Hydrazine

Technologies ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 53
Author(s):  
Bungo Ochiai ◽  
Yohei Shimada
Keyword(s):  
Low Temperature ◽  
Lower Critical Solution Temperature ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Ambient Temperatures ◽  
Safe Storage ◽  
Release System ◽  
And Storage ◽  
Hydrazine Solution

A reversible gelation–release system was developed for safe storage of toxic hydrazine solution based on gelation at lower critical solution temperature (LCST). Poly(N-isopropylacrylamide) (PNIPAM) and its copolymer could form gels of 35wt% hydrazine by dissolution under low temperature and storage at ambient temperatures. For example, PNIPAM gelled a 63 fold heavier amount of 35wt% hydrazine. Aqueous hydrazine was released from the gels by compression or heating, and the gelation–release cycles proceeded quantitatively (> 95%). The high gelation ability and recyclability are suitable for rechargeable systems for safe storage of hydrazine fuels.

N-isopropylacrylamide-based Copolymers with Time-dependent LCST for a Bioresorbable Carrier

2004 ◽  
Vol 845 ◽  
Author(s):  
Bae Hoon Lee ◽  
Brent Vernon
Keyword(s):  
Body Temperature ◽  
Time Dependent ◽  
Solution Temperature ◽  
Gelation Temperature ◽  
Critical Solution Temperature ◽  
New Class ◽  
Polymeric Biomaterials ◽  
Localized Delivery ◽  
Hydrolysis Of

ABSTRACTTo develop a new class of in situ-forming, injectable, and biodegradable polymeric biomaterials based on time-dependent lower critical solution temperature (LCST) properties for localized delivery, copolymers of N-isopropylacrylamide (NIPAAm), 2-hydroxyethyl methacryl lactate (HEMA-lactate) and acrylic acid (AAc) were prepared with varying mole ratios of monomers. The copolymers showed LCST and gelation properties below body temperature in 0.1 N PBS solution of pH 7.4. The LCST and gelation temperature of the copolymers decreased as the HEMA-lactate content of the copolymers was increased. The copolymers also showed time-dependent LCST and gelation properties in 0.1 N PBS solution of pH 7.4 owing to hydrolysis of HEMA-lactate. Hydrolysis of HEMA-lactate caused the polymers to be more hydrophilic, resulting in an increase in LCST and gelation temperature. All the polymers with about 6 mol % AAc exhibited LCST and gelation temperature above body temperature after complete hydrolysis of HEMA-lactate.

Variability in, variability out: best practice recommendations to standardize pre-analytical variables in the detection of circulating and tissue microRNAs

2017 ◽  
Vol 55 (5) ◽  
Author(s):  
Jenna Khan ◽  
Joshua A. Lieberman ◽  
Christina M. Lockwood
Keyword(s):  
Best Practice ◽  
Rna Extraction ◽  
Storage Conditions ◽  
Sample Collection ◽  
Ischemic Time ◽  
Cold Ischemic Time ◽  
C Storage ◽  
Tissue Specimens ◽  
And Storage

Abstract:microRNAs (miRNAs) hold promise as biomarkers for a variety of disease processes and for determining cell differentiation. These short RNA species are robust, survive harsh treatment and storage conditions and may be extracted from blood and tissue. Pre-analytical variables are critical confounders in the analysis of miRNAs: we elucidate these and identify best practices for minimizing sample variation in blood and tissue specimens. Pre-analytical variables addressed include patient-intrinsic variation, time and temperature from sample collection to storage or processing, processing methods, contamination by cells and blood components, RNA extraction method, normalization, and storage time/conditions. For circulating miRNAs, hemolysis and blood cell contamination significantly affect profiles; samples should be processed within 2 h of collection; ethylene diamine tetraacetic acid (EDTA) is preferred while heparin should be avoided; samples should be “double spun” or filtered; room temperature or 4 °C storage for up to 24 h is preferred; miRNAs are stable for at least 1 year at –20 °C or –80 °C. For tissue-based analysis, warm ischemic time should be <1 h; cold ischemic time (4 °C) <24 h; common fixative used for all specimens; formalin fix up to 72 h prior to processing; enrich for cells of interest; validate candidate biomarkers with in situ visualization. Most importantly, all specimen types should have standard and common workflows with careful documentation of relevant pre-analytical variables.

scholarly journals Evaluation of Contamination Risks Due to the Sale and Storage Conditions of Smoked, Dried and Fresh Fishes in Ouagadougou

2021 ◽  
pp. 42-54
Author(s):  
Arouna Ouedraogo ◽  
Cheikna Zongo ◽  
François Tapsoba ◽  
Hama Cissé ◽  
Yves Traoré ◽  
...  
Keyword(s):  
Burkina Faso ◽  
Storage Period ◽  
Storage Conditions ◽  
Smoked Fish ◽  
Different Types ◽  
And Storage ◽  
Fish Industry ◽  
Fish Trade ◽  
Temperature Storage

Aims: Fish is a product more and more consumed in Burkina Faso, especially in Ouagadougou. Poor sale and storage conditions can impact on the hygienic quality of fish. The objective of this study was to identify the contamination risks due to the sale and storage conditions of smoked, dried and fresh fishes. Study Design: A descriptive design was used to identify the different types and origins of fish on the markets in Ouagadougou and the practices and conditions of sale that could be sources of chemical and microbiological contamination. Place and Duration of Study: Relevant data was collated in Ouagadougou (Burkina Faso) from February 2019 to July 2019. Methodology: A survey was conducted among traders of dried and smoked fish from 50 markets and major sales sites in Ouagadougou. Data collection was done using a questionnaire developed with Sphinx Plus2 software. Results: The results indicated a higher proportion of men (75%) than women (25%) with an age between 21 and 45 years old were participated in fish trade. The fish encountered in the markets of Ouagadougou come from Sourou, Kompienga and Bagré, as well as from external suppliers such as Côte d'Ivoire, Mali and Senegal. The different types of fish sold were dried or smoked carp (36.67%), smoked catfish (23.33%), dried Nanani or Djêdjê wala (concorde) (13.33%), smoked Macharon (10%), smoked Racok (10%) and smoked eels or Roolgo in mooré (local language) (6.67%). The types of fish most purchased by consumers, in order, were: Carp, Catfish, Macharon, Nanani. In addition, the study detected risks of contamination of the fish, namely: exposure material consisting of tables and baskets, conservation at room temperature, storage period of 10 to 30 days, no training in hygiene, fish served with bare hands, exposed to dust and stray animals. Conclusion: In sum, the study revealed some characteristics of the fish industry in Ouagadougou and also risks of contamination of fish sold on the markets.

Probing the thermal collapse of PNIPAM grafts by quantitative in situ ellipsometry

2013 ◽  
Vol 1544 ◽  
Author(s):  
E.S. Kooij ◽  
X.F. Sui ◽  
M.A. Hempenius ◽  
H.J.W. Zandvliet ◽  
G.J. Vancso
Keyword(s):  
Density Profile ◽  
Spectroscopic Ellipsometry ◽  
Quantitative Description ◽  
Solution Temperature ◽  
Thickness Variation ◽  
Dense Layer ◽  
Chain Segment ◽  
Critical Solution Temperature ◽  
Gradient Density

ABSTRACTWe demonstrate the potential of spectroscopic ellipsometry for the investigation of the chain segment density profile and layer thickness during the temperature-induced, reversible collapse−expansion transition of poly(N-isopropylacrylamide) (PNIPAM) grafted layers with variable grafting densities in aqueous systems. To obtain a quantitative description of the thickness of our swollen PNIPAM layers, various models were implemented to fit the ellipsometric data. From the ellipsometry results, the density and thickness variation accompanying the collapse transition across the lower critical solution temperature (LCST) was characterized. The collapse can be adequately explained by considering the PNIPAM film to consist of two layers: (i) a dense layer near the surface and (ii) a more diluted layer with a gradient density profile on the side of the film exposed to the solvent.

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