scholarly journals Laccase Immobilized Fe3O4-Graphene Oxide Nanobiocatalyst Improves Stability and Immobilization Efficiency in the Green Preparation of Sulfa Drugs

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 459 ◽  
Author(s):  
Shamila Rouhani ◽  
Shohreh Azizi ◽  
Rose W. Kibechu ◽  
Bhekie B Mamba ◽  
Titus A. M. Msagati

This paper, reports on the novel and green synthesis procedure for sulfonamides that involved the immobilization of Trametes Versicolor laccase onto the Fe3O4–graphene nanocomposite via glutaraldehyde (GA) crosslinking (Lac/Fe3O4/GO). Various parameters, mainly, activation time, GA, and laccase concentration were investigated and optimized. The results showed that the optimal contact time was 4 h, GA concentration was 5% while laccase concentration was 5 mg·mL−1, at which a high enzyme activity recovery was achieved (86%). In terms of the stability of immobilized laccase to temperature and storage conditions, the performance of the nanobiocatalyst was found to significantly exceed that of free laccase. The results have indicated that nearly 70% of relative activity for immobilized laccase remained after the incubation period of 2 h at 55 °C, but only 48% of free laccase remained within the same time period. Moreover, the immobilized laccase retained 88% of its initial activity after storage for 20 days. In case of the free laccase, the activity retained within the same time period was 32%. In addition, the nanobiocatalyst possessed better recycling performance as evidenced from the observation that after eight cycles of repeated use, it retained 85% of its original activity.

1989 ◽  
Vol 35 (10) ◽  
pp. 972-974 ◽  
Author(s):  
Alain Lamarre ◽  
Pierre J. Talbot

The stability of human coronavirus 229E infectivity was maximum at pH 6.0 when incubated at either 4 or 33 °C. However, the influence of pH was more pronounced at 33 °C. Viral infectivity was completely lost after a 14-day incubation period at 22, 33, or 37 °C but remained relatively constant at 4 °C for the same length of time. Finally, the infectious titer did not show any significant reduction when subjected to 25 cycles of thawing and freezing. These studies will contribute to optimize virus growth and storage conditions, which will facilitate the molecular characterization of this important pathogen.Key words: coronavirus, pH, temperature, infectivity, human coronavirus.


Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1029
Author(s):  
Francesca Selmin ◽  
Umberto M. Musazzi ◽  
Silvia Franzè ◽  
Edoardo Scarpa ◽  
Loris Rizzello ◽  
...  

Moving towards a real mass vaccination in the context of COVID-19, healthcare professionals are required to face some criticisms due to limited data on the stability of a mRNA-based vaccine (Pfizer-BioNTech COVID-19 Vaccine in the US or Comirnaty in EU) as a dose in a 1 mL-syringe. The stability of the lipid nanoparticles and the encapsulated mRNA was evaluated in a “real-life” scenario. Specifically, we investigated the effects of different storing materials (e.g., syringes vs. glass vials), as well as of temperature and mechanical stress on nucleic acid integrity, number, and particle size distribution of lipid nanoparticles. After 5 h in the syringe, lipid nanoparticles maintained the regular round shape, and the hydrodynamic diameter ranged between 80 and 100 nm with a relatively narrow polydispersity (<0.2). Samples were stable independently of syringe materials and storage conditions. Only strong mechanical stress (e.g., shaking) caused massive aggregation of lipid nanoparticles and mRNA degradation. These proof-of-concept experiments support the hypothesis that vaccine doses can be safely prepared in a dedicated area using an aseptic technique and transferred without affecting their stability.


Pharmaceutics ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 294 ◽  
Author(s):  
Xinyue Huang ◽  
Helen E Townley

Mesoporous silica nanoparticles (MSNPs) have the potential to be used as antigen carriers due to their high surface areas and highly ordered pore network. We investigated the adsorption and desorption of diphtheria toxoid as a proof-of-concept. Two series of nanoparticles were prepared—(i) small pores (SP) (<10 nm) and (ii) large pores (LP) (>10 nm). SBA-15 was included as a comparison since this is commercially available and has been used in a large number of studies. External diameters of the particles ranged from 138 to 1509 nm, surface area from 632 to 1110 m2/g and pore size from 2.59 to 16.48 nm. Antigen loading was assessed at a number of different ratios of silica-to-antigen and at 4 °C, 20 °C and 37 °C. Our data showed that protein adsorption by the SP series was in general consistently lower than that shown by the large pore series. Unloading was then examined at 4 °C, 20 °C and 37 °C and a pH 1.2, 4.5, 6.8 and 7.4. There was a trend amongst the LP particles towards the smallest pores showing the lowest release of antigen. The stability of the MSNP: antigen complex was tested at two different storage temperatures, and storage in solution or after lyophilization. After 6 months there was negligible release from any of the particles under any of the storage conditions. The particles were also shown not to cause hemolysis.


2017 ◽  
Vol 5 (1) ◽  
pp. 32-36 ◽  
Author(s):  
Firdaus Firdaus ◽  
Seniwati Dali ◽  
Hendra J. Rusman

This research aims to immobilization; characterize the enzyme of immobilized, test the effectiveness of the enzyme of immobilized. This research begins with the immobilization to process of enzyme lipase using activated carbon matrix, enzyme characterization covering of immobile determination of temperature and pH optimum of the enzyme of immobilized, as well as test the stability of work covering immobilized of enzyme the test thermal stability and repeated use. The results showed that the immobile of enzyme work optimally at 50oC of temperature and pH 6.5 with each activity 0.040 U/mL; research results also showed that the immobile of enzyme has higher thermal stability in comparison with the free enzyme: with the relative activity of 57.50% at the time of 45 minutes of exposure and the exposure time at 47.50% at 75-105 minutes and it can be used as many as six times with the relative activity of 52.5% in 6 times of use.


Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2708
Author(s):  
Georgi Iliev ◽  
Louis Hardan ◽  
Cynthia Kassis ◽  
Rim Bourgi ◽  
Carlos Enrique Cuevas-Suárez ◽  
...  

This paper presents state of the art universal adhesive systems and the effect of shelf-life and storage conditions on their bond performance. Three topics are explored in this review: an introduction to the topic, the mechanisms responsible for the degradation of the hybrid layer, and the factors that play a role in the stability of universal adhesives. In addition, issues such as potential durability and clinical importance are discussed. Universal adhesive systems are promising but must be handled and stored according to the manufacturer’s instructions, with careful attention given to the details of shelf-life and storage conditions for maximal success. It appears that the components of universal adhesives play an important role in their stability. Furthermore, HEMA-free formulations using methacrylamides lead to longer shelf-life. Further research is needed to prove these hypotheses.


2015 ◽  
Vol 7 (2) ◽  
pp. 99-109 ◽  
Author(s):  
Nadežda Prica ◽  
Milica Živkov Baloš ◽  
Sandra Jakšić ◽  
Željko Mihaljev ◽  
Brankica Kartalović ◽  
...  

The color, aroma and fl avor are major sensory characteristics of honey, which are mainly determined by the botanical origin of honey as well as by processing and storage conditions. Increased moisture content above the maximum permitted level could result in honey spoilage, which aff ects its sensory properties. The higher water-in-honey content, the greater possibility of yeast fermentation and thus the change of the fl avor and color ofhoney. Fermentation process results in alcohol formation and, in the presence of oxygen, the alcohol will break down to acetic acid and water, which causes honey to have sour taste. Thus, moisture content of honey is a critical parameter for its quality as it aff ects the stability of honey and its resistance to microbial spoilage during storage. Physicochemical analysis of moisture content and acidity of honey play an important role in determining the overall characteristic of honey and final assessment of its quality. In this study, the investigation of aforementioned parameters resulted in positive quality assessment for 48 of 50 examined honey samples produced in 2013 in the territory of Vojvodina.


2019 ◽  
Vol 07 (01) ◽  
pp. 006-010 ◽  
Author(s):  
Girish Khurana ◽  
Vipul Gupta

AbstractInsulin is a naturally occurring hormone secreted by the pancreas. Insulin is required by the body cellsto remove and use glucose from the blood. The insulin and its various analogues are essential in management of type 1 diabetes mellitus. This study has been done to analyze how variation in various storage conditions and climatic changes causes change in therapeutic efficacy. Storage condition affects the stability of insulin as observed in a study in which insulin stored at temperature between 32 and 37°C showed 14 to 18% decrease in its potency and could not cause a significant decrease in blood sugar level when compared with those receiving insulin stored at 5°C. This work was done with the aim of finding the effect of climatic changes and storage condition on efficacy of insulin.


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