scholarly journals Design of Aerogels, Cryogels and Xerogels of Alginate: Effect of Molecular Weight, Gelation Conditions and Drying Method on Particles’ Micromeritics

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1049 ◽  
Author(s):  
Rosalía Rodríguez-Dorado ◽  
Clara López-Iglesias ◽  
Carlos García-González ◽  
Giulia Auriemma ◽  
Rita Aquino ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Physicochemical Properties ◽  
Textural Properties ◽  
Supercritical Drying ◽  
Processing Parameters ◽  
Storage Conditions ◽  
Drying Methods ◽  
Drying Method ◽  
Molecular Weights ◽  
Nanostructured Particles

Processing and shaping of dried gels are of interest in several fields like alginate aerogel beads used as highly porous and nanostructured particles in biomedical applications. The physicochemical properties of the alginate source, the solvent used in the gelation solution and the gel drying method are key parameters influencing the characteristics of the resulting dried gels. In this work, dried gel beads in the form of xerogels, cryogels or aerogels were prepared from alginates of different molecular weights (120 and 180 kDa) and concentrations (1.25, 1.50, 2.0 and 2.25% (w/v)) using different gelation conditions (aqueous and ethanolic CaCl2 solutions) and drying methods (supercritical drying, freeze-drying and oven drying) to obtain particles with a broad range of physicochemical and textural properties. The stability of physicochemical properties of alginate aerogels under storage conditions of 25 °C and 65% relative humidity (ICH-climatic zone II) during 1 and 3 months was studied. Results showed significant effects of the studied processing parameters on the resulting alginate dried gel properties. Stability studies showed small variations in aerogels weight and specific surface area after 3 months of storage, especially, in the case of aerogels produced with medium molecular weight alginate.

Aging Study of Gold Nanoparticles Functionalized with Chitosan in Aqueous Solutions

2017 ◽  
Vol 68 (10) ◽  
pp. 2385-2388
Author(s):  
Raoul Vasile Lupusoru ◽  
Laurentiu Simion ◽  
Ion Sandu ◽  
Daniela Angelica Pricop ◽  
Aurica Chiriac ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Physicochemical Properties ◽  
Aqueous Solutions ◽  
Colloidal Stability ◽  
Chemical Reduction ◽  
Storage Conditions ◽  
Chemical Reduction Method ◽  
Molecular Weights ◽  
Aging Period ◽  
Aging Study

We studied the way in which stability and physicochemical properties of gold (Au) nanoparticles (NP) coated with chitosan are influenced by the molecular weight of chitosan and Au precursor concentration when samples are subjected to aging. Pharmaceutical use of AuNPs coated with chitosan is closely related to stability and physicochemical properties in relation to storage conditions and processing. For this purpose, series of AuNPs of different sizes were prepared by aqueous chemical reduction method using chitosan with various molecular weights as template. The physicochemical properties and stability at room temperature of AuNPs in aqueous solutions of chitosan have been investigated by following the temporal evolution of surface plasmon absorbance, Zeta potential, average dimension, and Au-chitosan interaction, after synthesis and through a period of 24 months. In our experiment, during the observed aging period, the AuNPs coated with chitosan presented a better colloidal stability, while using chitosan with medium molecular weight and medium concentration of Au precursor.

scholarly journals The effect of the drying method on the cell wall structure and sorption properties of waterlogged archaeological wood

2021 ◽  
Author(s):  
Magdalena Broda ◽  
Simon F. Curling ◽  
Marcin Frankowski
Keyword(s):  
Cell Wall ◽  
Supercritical Drying ◽  
Wood Properties ◽  
Storage Conditions ◽  
Cell Wall Structure ◽  
Sorption Properties ◽  
Wall Structure ◽  
Drying Methods ◽  
Drying Method ◽  
Archaeological Wood

AbstractDrying is a process affecting various wood properties, including its structure, moisture behaviour and mechanical properties. Since waterlogged wooden artefacts usually constitute priceless objects of cultural heritage, understanding the effect of drying on the complex interactions between the wood ultrastructure and the resulting properties is necessary to ensure their proper conservation. Hence, this was the aim of the present study, with a particular emphasis on the influence of drying conditions on the relations between the cell wall structure, dimensional stability and hygroscopicity of degraded archaeological wood. The choice of the particular drying methods was dictated by their final effect on wood appearance (dimensions). The results obtained clearly show that depending on the drying method applied, the resulting material differs significantly in structure, dimensions and sorption properties, despite the same degree of wood degradation. Air- and oven-drying resulted in the highest wood shrinkage, lower porosity, and a decreased number of free hydroxyls in the wood cell wall. The best wood dimensional stabilisation and the highest porosity were ensured by freeze- and supercritical drying. No correlations were found between wood structure and moisture behaviour. The outcome of the research may be useful for conservators who plan to provide the artefacts with proper storage conditions and effective conservation/reconservation.

Ruthenium Recovery from Acetic Acid Waste Solution by Using PEI-Coated Biomass-Chitosan Composite Fiber

2015 ◽  
Vol 1130 ◽  
pp. 577-580 ◽  
Author(s):  
Jeong Ae Kim ◽  
Myung Hee Song ◽  
Yeoung Sang Yun
Keyword(s):  
Molecular Weight ◽  
Acetic Acid ◽  
Freeze Drying ◽  
Ion Exchange Resin ◽  
Composite Fiber ◽  
Drying Methods ◽  
Drying Method ◽  
Waste Solution ◽  
Chitosan Composite ◽  
Acid Waste

Polyethylenimine (PEI)-coated biomass-chitosan composite fiber (PBCF) was fabricated to recover Ru from acetic acid waste solution. The present work aimed to understand the effects of molecular weight of chitosan and drying method on stability and sorption performance of the PBCF. For this, the PBCF was prepared by extruding the mixed solutions of chitosan and Corynebacteriumglutamicum to form the composite fibers which were modified with ionic polymer, PEI. The degree of swelling of PBCFs prepared by hot-air, natural, and freeze drying methods were 1.25, 1.34, and 1.07 %, respectively, indicating that the freeze-drying method was the best. Batch biosorption studies showed that the maximum Ru uptake could be achieved with PBCF prepared with medium molecular weight chitosan, and could reach 34.1 mg/g, which was 7.9 times higher than that of the commercial ion exchange resin, LEWATIT® MonoPlus M 500 (4.3 mg/g). Therefore, PBCF can be considered as an alternative sorbent to synthetic resin for recovery of Ru form industrial acetic acid waste solution.

scholarly journals Physicochemical Properties of Dried Apple Slices: Impact of Osmo-Dehydration, Sonication, and Drying Methods

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1078
Author(s):  
Joanna Cichowska-Bogusz ◽  
Adam Figiel ◽  
Angel Antonio Carbonell-Barrachina ◽  
Marta Pasławska ◽  
Dorota Witrowa-Rajchert
Keyword(s):  
Physicochemical Properties ◽  
Osmotic Dehydration ◽  
Convective Drying ◽  
Drying Methods ◽  
Drying Method ◽  
Drying Time ◽  
Hygroscopic Properties ◽  
Fruit Samples ◽  
Apple Slices ◽  
Pre Treatment

Apple slices of the Elise variety were previously osmo-dehydrated in erythritol, xylitol, and sucrose for 2 h. In some parts of the experiment, 30 min of ultrasound pre-treatment (US) were applied. Afterwards, fruit samples were dried by convective (CD), microwave-vacuum (VM), and a combined method (CD/VM, mix two of them). The main aim of the research was to characterize an impact of osmotic dehydration, sonication pre-treatment, and drying method on the physicochemical properties of the dried apples. The use of sugar alcohols (xylitol, erythritol) in the production of dried apples did not badly affect the taste of the obtained dried products; it enabled a noticeable cooling/refreshing effect felt in the mouth when consuming a snack, and enabled the production of dried snacks with lower calorific value. Polyol residues in the product were at a level that was safe for consumers. The most popular convective drying was long lasting, whereas the VM drying method allowed for the shortest drying time, amounting to 76 min; moreover, additional application of ultrasounds reduced this time to 36 min. The combined drying method allowed the total duration of the process to be reduced 2–4.5 times. Ultrasound applied during osmotic dehydration did not significantly affect attributes of the descriptive sensory analysis for the obtained dried apples. The best hygroscopic properties, ensuring the storage stability of the dried product, showed dried apples previously osmo-dehydrated in erythritol and sucrose solutions.

scholarly journals Effects of Storage Conditions on Degradation of Chlorophyll and Emulsifying Capacity of Thylakoid Powders Produced by Different Drying Methods

Foods ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 669
Author(s):  
Karolina Östbring ◽  
Ingegerd Sjöholm ◽  
Marilyn Rayner ◽  
Charlotte Erlanson-Albertsson
Keyword(s):  
Relative Humidity ◽  
Spray Drying ◽  
Freeze Drying ◽  
Functional Foods ◽  
Storage Conditions ◽  
Drying Methods ◽  
Drying Method ◽  
Equivalent Effect ◽  
Emulsifying Capacity

Thylakoid membranes isolated from spinach have previously been shown to inhibit lipase/co-lipase and prolong satiety in vivo. There is a need to develop thylakoid products that not only have the desired characteristics and functionality after processing, but also are stable and provide equivalent effect on appetite over the promised shelf life. The aim of the present study was therefore to evaluate how the thylakoid powders’ characteristics and functionality were affected by moisture during storage. Thylakoids produced by drum-drying, spray-drying, and freeze-drying were incubated in controlled atmosphere with different relative humidity (10 RH%, 32 RH%, 48 RH% and 61 RH%) for 8 months. The water content in all powders was increased during storage. The water absorption was moisture-dependent, and the powders were considered hygroscopic. Relative humidity showed a definite influence on the rate of chlorophyll degradation and loss of green color in thylakoid powders after storage which correlated with impaired emulsifying capacity. Spray-dried powder had the overall highest chlorophyll content and emulsifying capacity at all RH-levels investigated. Spray drying was therefore considered the most suitable drying method yielding a powder with best-maintained functionality after storage. The results can be applied towards quality control of high-quality functional foods with appetite suppressing abilities.

scholarly journals Effect of prebiotic content on functional and physicochemical properties of Lactobacillus casei loaded chitosan-Ca-alginate microparticles

2012 ◽  
Vol 58 ◽  
pp. 42-52 ◽  
Author(s):  
Tanja Petreska Ivanovska ◽  
Kristina Mladenovska ◽  
Zoran Kavrakovski ◽  
Liljana Bogdanovska ◽  
Anita Grozdanov ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Spray Drying ◽  
Lactobacillus Casei ◽  
Storage Conditions ◽  
Drying Method ◽  
Significant Difference ◽  
Ca Alginate

This study aims to evaluate the influence of different concentrations of fructooligosaccharide (FOS) as prebiotic on functional and physicochemical properties of Lactobacillus casei loaded chitosan-Ca-alginate microparticles prepared by spray-drying method, after preparation and 6-month storage at 4 °C. Prebiotic compound positively influenced the viability of L. casei during preparation of the microparticles and in storage conditions, while no significant difference of the probiotic viability was observed when different concentrations of FOS in a range of 1.5 - 5% w/w were applied. Having in regard that non-significant improvement in the functional and physicochemical properties of the microparticles with increased content of the FOS was observed, the concentration of 1.5% w/w was recommended as an optimal for preparation of synbiotic loaded microparticles.

scholarly journals Purification, Physicochemical Properties, and Antioxidant Activities of Two Low-Molecular-Weight Polysaccharides from Ganoderma leucocontextum Fruiting Bodies

Antioxidants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1145
Author(s):  
Xiong Gao ◽  
Jiayi Qi ◽  
Chi-Tang Ho ◽  
Bin Li ◽  
Yizhen Xie ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Physicochemical Properties ◽  
Antioxidant Activities ◽  
Molecular Surface ◽  
Low Molecular Weight ◽  
Fruiting Bodies ◽  
Nih3t3 Cells ◽  
Antioxidant Power ◽  
Molecular Weights ◽  
Ferric Reducing Antioxidant Power

Two low-molecular-weight polysaccharides (GLP-1 and GLP-2) were purified from Ganoderma leucocontextum fruiting bodies, and their physicochemical properties and antioxidant activities were investigated and compared in this study. The results showed that GLP-1 and GLP-2 were mainly composed of mannose, glucose, galactose, xylose, and arabinose, with weight-average molecular weights of 6.31 and 14.07 kDa, respectively. Additionally, GLP-1 and GLP-2 had a similar chain conformation, crystal structure, and molecular surface morphology. Moreover, GLP-1 exhibited stronger antioxidant activities than GLP-2 in five different assays: 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), hydroxyl radical, superoxide anion radical, ferric reducing antioxidant power (FRAP), and oxygen radical antioxidant capacity (ORAC). The main linkage types of GLP-1 were found to be →4)-α-D-Glcp-(1→, →4)-β-D-Glcp-(1→, →3)-β-D-Glcp-(1→, →6)-β-D-Galp-(1→, →6)-α-D-Glcp-(1→, →4,6)-α-D-Glcp-(1→, and Glcp-(1→ by methylation analysis and nuclear magnetic resonance (NMR) spectroscopy. In addition, GLP-1 could protect NIH3T3 cells against tert-butyl hydroperoxide (tBHP)-induced oxidative damage by increasing catalase (CAT) and glutathione peroxidase (GSH-Px) activities, elevating the glutathione/oxidized glutathione (GSH/GSSG) ratio, and decreasing the malondialdehyde (MDA) level. These findings indicated that GLP-1 could be explored as a potential antioxidant agent for application in functional foods.

scholarly journals Physicochemical Properties of Solutions of Polyvinyl Alcohol (PVA) of Different Molecular Weights

2021 ◽  
Vol 6 (2) ◽  
pp. 242-248
Author(s):  
V. V. Chekanova ◽  
◽  
Yu. S. Pakhomova ◽  
A. M. Kompaniets ◽  
V. A. Kireev ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Surface Tension ◽  
Physicochemical Properties ◽  
Dynamic Viscosity ◽  
Critical Concentration ◽  
Micelle Formation ◽  
Molecular Weights ◽  
Melting Temperatures ◽  
Molecular Masses ◽  
Pva Solutions

The physicochemical properties (surface tension, dynamic viscosity, crystallization and melting temperatures) of polyvinyl alcohol solutions of molecular weight 9, 31 and 72 kDa have been studied. The surface tension and the critical concentration of micelle formation were determined by the method of stalogometry, and the dynamic viscosity was determined using an Oswald viscometer. The crystallization and melting temperatures were determined in a cooled modified chamber of the UOP-6 software freezer at a rate of 2°C/min. Cryomicroscopic studies were carried out on a polarizing microscope "MIN-8". The surface tension reflects the interaction of PVA solutions with the lipid layer of biomembranes and indicates the hydrophobic properties of substances. The viscosity of PVA solutions characterizes their interaction with water molecules and reflects hydrophilic interactions. The purpose of the study is to determine the physicochemical properties of PVS that characterize the hydrophilic-hydrophobic interactions in the studied solutions and the micelle formation of PVА solutions of different molecular weights. Materials and methods. Studies of the dynamic viscosity and density of 0.1%-1% PVA solutions of molecular weight 9, 31 kDa showed that these parameters increase with increasing PVA concentration, which leads to increased hydrophilicity of the solutions. Results and discussion. It was shown that the surface tension of PVA solutions decreases with increasing concentration, which leads to a decrease in the hydrophobic properties of the polymer. It was found that in 0.5% PVА solutions of molecular weight 9 and 31 kDa the crystallization and melting temperatures decrease from -5 to -6°C. At these temperatures, crystallization and melting of the solutions begin. Conclusion. The study of micelle formation in PVА solutions of different molecular masses was carried out, surface tension isotherms were constructed, and the break point on the isotherm corresponding to the CCM was determined. The values of the critical concentration of micelle formation of PVА of molecular masses 9, 31, 72 kDa were determined. Hydrophobic links of PVА of molecular masses 9 and 31 kDa form hydrophobic cavities in the micelle structure, which can reduce recrystallization activity

Investigation by HPLC of the Catabolism of Recombinant Tissue Plasminogen Activator in the Rat

1988 ◽  
Vol 60 (01) ◽  
pp. 107-112 ◽  
Author(s):  
Roy Harris ◽  
Louis Garcia Frade ◽  
Lesley J Creighton ◽  
Paul S Gascoine ◽  
Maher M Alexandroni ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Half Life ◽  
Recombinant Tissue Plasminogen Activator ◽  
Rat Plasma ◽  
High Molecular Weight Complex ◽  
Molecular Weights ◽  
Major Activity ◽  
Tissue Plasminogen

SummaryThe catabolism of recombinant tissue plasminogen activator (rt-PA) was investigated after injection of radiolabelled material into rats. Both Iodogen and Chloramine T iodination procedures yielded similar biological activity loss in the resultant labelled rt-PA and had half lives in the rat circulation of 1 and 3 min respectively. Complex formation of rt-PA was investigated by HPLC gel exclusion (TSK G3000 SW) fractionation of rat plasma samples taken 1-2 min after 125I-rt-PA injection. A series of radiolabelled complexes of varying molecular weights were found. However, 60% of the counts were associated with a single large molecular weight complex (350–500 kDa) which was undetectable by immunologically based assays (ELISA and BIA) and showed only low activity with a functional promoter-type t-PA assay. Two major activity peaks in the HPLC fractions were associated with Tree t-PA and a complex having a molecular weight of ̴ 180 kDa. HPLC fractionation to produce these three peaks at various timed intervals after injection of 125I-rt-PA showed each to have a similar initial rate half life in the rat circulation of 4-5 min. The function of these complexes as yet is unclear but since a high proportion of rt-PA is associated with a high molecular weight complex with a short half life in the rat, we suggest that the formation of this complex may be a mechanism by which t-PA activity is initially regulated and finally cleared from the rat circulation.

Permeability Enhancing and Chemotactic Activities of Lower Molecular Weight Degradation Products of Human Fibrinogen

1981 ◽  
Vol 45 (01) ◽  
pp. 090-094 ◽  
Author(s):  
Katsuo Sueishi ◽  
Shigeru Nanno ◽  
Kenzo Tanaka
Keyword(s):  
Molecular Weight ◽  
Degradation Products ◽  
Electron Microscopic Observation ◽  
Chemotactic Activity ◽  
Lower Molecular Weight ◽  
Electron Microscopic ◽  
Human Fibrinogen ◽  
Rabbit Skin ◽  
Molecular Weights ◽  
Active Fragments

SummaryFibrinogen degradation products were investigated for leukocyte chemotactic activity and for enhancement of vascular permeability. Both activities increased progressively with plasmin digestion of fibrinogen. Active fragments were partially purified from 24 hr-plasmin digests. Molecular weights of the permeability increasing and chemotactic activity fractions were 25,000-15,000 and 25,000 respectively. Both fractions had much higher activities than the fragment X, Y, D or E. Electron microscopic observation of the small blood vessels in rabbit skin correlated increased permeability with the formation of characteristic gaps between adjoining endothelial cells and their contraction.These findings suggest that lower molecular weight degradation products of fibrinogen may be influential in contributing to granulocytic infiltration and enhanced permeability in lesions characterized by deposits of fibrin and/or fibrinogen.

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