scholarly journals Binary Solutions of Hyaluronan and Lactose-Modified Chitosan: The Influence of Experimental Variables in Assembling Complex Coacervates

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 897
Author(s):  
Federica Vecchies ◽  
Pasquale Sacco ◽  
Eleonora Marsich ◽  
Giuseppe Cinelli ◽  
Francesco Lopez ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Electrostatic Interactions ◽  
Weight Ratio ◽  
Mutual Solubility ◽  
Molecular Weights ◽  
Modified Chitosan ◽  
Ph Values ◽  
Oppositely Charged ◽  
Liquid Liquid Phase Separation

A miscibility study between oppositely charged polyelectrolytes, namely hyaluronic acid and a lactose-modified chitosan, is here reported. Experimental variables such as polymers’ weight ratios, pH values, ionic strengths and hyaluronic acid molecular weights were considered. Transmittance analyses demonstrated the mutual solubility of the two biopolymers at a neutral pH. The onset of the liquid-liquid phase separation due to electrostatic interactions between the two polymers was detected at pH 4.5, and it was found to be affected by the overall ionic strength, the modality of mixing and the polymers’ weight ratio. Thorough Dynamic Light Scattering (DLS) measurements were performed to check the quality of the formed coacervates by investigating their dimensions, homogeneity and surface charge. The whole DLS results highlighted the influence of the hyaluronic acid molecular weight in affecting coacervates’ dispersity and size.

scholarly journals Characterization of Chitosan/Hyaluronan Complex Coacervates Assembled by Varying Polymers Weight Ratio and Chitosan Physical-Chemical Composition

2020 ◽  
Vol 4 (1) ◽  
pp. 12
Author(s):  
Franco Furlani ◽  
Ivan Donati ◽  
Eleonora Marsich ◽  
Pasquale Sacco
Keyword(s):  
Surface Charge ◽  
Electrostatic Interactions ◽  
Weight Ratio ◽  
Water Soluble ◽  
Present System ◽  
Additional Parameter ◽  
Molecular Weights ◽  
Physical Chemical ◽  
Sodium Hyaluronan ◽  
Oppositely Charged

Herein, we synthetized and characterized polysaccharide-based complex coacervates starting from two water-soluble biopolymers, i.e., hydrochloride chitosans and sodium hyaluronan. We used chitosans encompassing a range of molecular weights from 30,000 to 400,000 and showing different fraction of acetylated units (i.e., FA = 0.16, 0.46, and 0.63). This set of chitosans was mixed with a low molecular weight hyaluronan to promote electrostatic interactions. Resulting colloids were analyzed in terms of size, polydispersity and surface charge by Dynamic Light Scattering. The weight ratio between the two polyelectrolytes was studied as additional parameter influencing the liquid-liquid phase separation. Main results include the following: the polymers weight ratio was fundamental in dictating the colloids surface charge, whereas chitosan physical-chemical features influenced the dimension and homogeneity of colloids. This contribution presents additional understanding of the complex coacervation between these two oppositely charged polysaccharides, with the potential translation of present system in food and biomedical sectors.

scholarly journals Characterization of Methotrexate Loaded Fucoidan/Chitosan Nanoparticles

2020 ◽  
Vol 11 (SPL4) ◽  
pp. 2644-2654
Author(s):  
Venkatesan Kotteeswaran ◽  
Vidhyutha Srivathsan ◽  
Mahima Bhandari ◽  
Juanit Thomas E ◽  
Trishita Bhattacharya
Keyword(s):  
Electrostatic Interactions ◽  
Chitosan Nanoparticles ◽  
Weight Ratio ◽  
Entrapment Efficiency ◽  
Structural Morphology ◽  
Constant Ph ◽  
Covalently Bonded ◽  
Inflammatory Drugs ◽  
The Difference ◽  
Oppositely Charged

Methotrexate is one of the most popular and safe anti-inflammatory drugs which is an antifolate-type antimetabolite and is used as an anticancer drug. In this study, oppositely charged chitosan and fucoidan have been non-covalently bonded using their electrostatic interactions with the methotrexate drug loaded into these nanoparticles. Fucoidan is obtained from marine algae which are composed of l-fucose and sulfate groups in various types of brown seaweeds; whereas chitosan is a naturally occurring biopolymer obtained through the N-deacetylation of chitin. Depending on the fucoidan / chitosan (F / C) weight ratio, three distinct nanoparticles (1F / 1C; 3F / 1C; 5F / 1C) are synthesized and characterized. Nanoparticles were prepared using cross linkers EDC and NHS at a constant pH to reduce the conjugate size. The prepared conjugates were characterized for their size and zeta potential using DLS analysis and the functional groups were analysed using FTIR. DLS results proclaimed that there was size reduction in particle size with cross linker and without the drug methotrexate. The 5:1 F/C nanoparticles was seen to be 441.5 nm, the difference being considerable larger in the 5:1 formulation. Hence for further analysis 5:1 F/C nanoparticles were preferred. Maximum entrapment efficiency was observed in 5:1 F/C nanoparticle with and without cross linkers. To understand the structural morphology of nanoparticles electromagnetic magnification like SEM and TEM were taken in account.

scholarly journals Changes in Water Quality of the River das Antas as It Passes through Rural and Urban Areas

Urban Science ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 22
Author(s):  
Valdemir Antoneli ◽  
Manuel Pulido-Fernández ◽  
João Anésio Bednarz ◽  
Leonardo Brandes ◽  
Michael Vrahnakis ◽  
...  
Keyword(s):  
Rural Area ◽  
Urban Areas ◽  
Human Consumption ◽  
Rural And Urban Areas ◽  
Ph Values ◽  
Rural And Urban ◽  
Feasible Option ◽  
Decreasing Ph ◽  
The City

The catchment area of River das Antas (Irati, Paraná, Brazil) is of high importance both for human consumption and irrigation. Within Irati, this river passes through a rural area and through the city of Irati, crossing both poor and rich neighbourhoods. We selected three study areas downstream (a rural area, poor community, and rich neighbourhood) in which we measured turbidity, the concentration of sediments and pH during rainy days. Our results showed downstream trends of increasing turbidity and concentrations of sediments with decreasing pH. The values of turbidity and of concentration of sediments were significantly different in the rural area, while the pH values were significantly different between the three study areas. These findings highlight the effect of agricultural activities in the generation of sediments and turbidity. The—presumably expected—effects of organic urban waste from the poor neighbourhood were also detected in the pH values. We conclude that efforts should be made to ensure that land planning and training/education programmes on sustainable farming practices are undertaken by the authorities to reduce water pollution and its effects on water bodies during rainfall events, since paving streets is not a feasible option in the short term due to the high costs associated with this measure.

scholarly journals Effect of Ferulic Acid-Grafted-Chitosan Coating on the Quality of Pork during Refrigerated Storage

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1374
Author(s):  
Guotian Wang ◽  
Yunpeng Liu ◽  
Huimin Yong ◽  
Shuai Zong ◽  
Changhai Jin ◽  
...  
Keyword(s):  
Ferulic Acid ◽  
Coupling Reaction ◽  
Thiobarbituric Acid ◽  
Antimicrobial Activities ◽  
Edible Coating ◽  
Thiobarbituric Acid Reactive Substances ◽  
Ph Values ◽  
Basic Nitrogen ◽  
Antioxidant And Antimicrobial Activities

Pork is perishable due to oxidation and microbial spoilage. Edible coating based on biopolymers and phenolic compounds is an effective way to preserve the quality of pork. In this study, ferulic acid-grafted-CS (ferulic acid-g-CS) with strong antioxidant and antimicrobial activities was synthesized through a carbodiimide-mediated coupling reaction. The obtained ferulic acid-g-CS was used as an edible coating material for fresh pork. The effect of ferulic acid-g-CS coating on the quality of pork during storage was investigated at 4 °C for 8 days. As compared to the uncoated pork, pork coated with CS and ferulic acid-g-CS showed lower total viable counts, total volatile basic nitrogen values, pH values, thiobarbituric acid reactive substances, and drip losses. Besides, pork coated with CS and ferulic acid-g-CS presented more compact microstructures than the uncoated pork at the eighth day. Sensory evaluation assay showed pork coated with CS and ferulic acid-g-CS had better color, odor, and over acceptance in comparison with the uncoated pork. Ferulic acid-g-CS coating, due to its relatively higher antioxidant and antimicrobial activities compared to CS coating, had a better performance in refrigerated pork preservation. Ferulic acid-g-CS coating effectively extended the shelf life of refrigerated pork to 7 days. This study revealed ferulic acid-g-CS coating was a promising technology for refrigerated pork preservation.

scholarly journals Hybrid Acrylated Chitosan and Thiolated Pectin Cross-Linked Hydrogels with Tunable Properties

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 266
Author(s):  
Shaked Eliyahu ◽  
Alexandra Galitsky ◽  
Esther Ritov ◽  
Havazelet Bianco-Peled
Keyword(s):  
Electrostatic Interactions ◽  
Profile Analysis ◽  
Hybrid Hydrogel ◽  
Texture Profile ◽  
Ph Values ◽  
X Ray Scattering ◽  
Wide Range ◽  
Michael Type Addition ◽  
Physical And Chemical ◽  
Hydrogel System

We developed and characterized a new hydrogel system based on the physical and chemical interactions of pectin partially modified with thiol groups and chitosan modified with acrylate end groups. Gelation occurred at high pectin thiol ratios, indicating that a low acrylated chitosan concentration in the hydrogel had a profound effect on the cross-linking. Turbidity, Fourier transform infrared spectroscopy, and free thiol determination analyses were performed to determine the relationships of the different bonds inside the gel. At low pH values below the pKa of chitosan, more electrostatic interactions were formed between opposite charges, but at high pH values, the Michael-type addition reaction between acrylate and thiol took place, creating harder hydrogels. Swelling experiments and Young’s modulus measurements were performed to study the structure and properties of the resultant hydrogels. The nanostructure was examined using small-angle X-ray scattering. The texture profile analysis showed a unique property of hydrogel adhesiveness. By implementing changes in the preparation procedure, we controlled the hydrogel properties. This hybrid hydrogel system can be a good candidate for a wide range of biomedical applications, such as a mucosal biomimetic surface for mucoadhesive testing.

Benefits of Using Diamond Dies for Cold Alternate Drawing of Magnesium Alloys

2016 ◽  
Vol 716 ◽  
pp. 13-21 ◽  
Author(s):  
Vladimir Stefanov Hristov ◽  
Kazunari Yoshida
Keyword(s):  
Magnesium Alloy ◽  
Weight Ratio ◽  
High Strength ◽  
Wire Drawing ◽  
High Ductility ◽  
Element Analysis ◽  
The Wire ◽  
Shearing Strain ◽  
Drawing Method

In recent years, due to its low density and high strength/weight ratio, magnesium alloy wires has been considered for application in many fields, such as welding, electronics, medical field (for production of stents). But for those purposes, we need to acquire wires with high strength and ductility. For that we purpose we proposed alternate drawing method, which is supposed to highly decrease the shearing strain near the surface of the wire after drawing, by changing the direction of the wire drawing with each pass and thus acquiring high ductility wires.We have done research on the cold alternate drawing of magnesium alloy wires, by conducting wire drawing of several magnesium wires and testing their strength, hardness, structure, surface and also finite element analysis, we have proven the increase of ductility at the expense of some strength.In this research we are looking to further improve the quality of the drawn wires by examining the benefits of using diamond dies over tungsten carbine dies. Using the alternate drawing method reduces the strength of the drawn wires and thus lowering their drawing limit. By using diamond dies we are aiming to decrease the drawing stress and further increase the drawing limit of the alternate drawn wires and also improve the quality of the finishing surface of the wires. With this in mind we are aiming to produce a good quality wire with low diameter, high ductility, high strength and fine wire surface.

Keeping Quality of Pacific Coast Dogfish

1959 ◽  
Vol 16 (6) ◽  
pp. 791-794 ◽  
Author(s):  
R. H. Moyer ◽  
B. A. Southcott ◽  
E. G. Baker ◽  
H. L. A. Tarr
Keyword(s):  
Pacific Coast ◽  
Sea Water ◽  
Total Volatile ◽  
Bacterial Counts ◽  
Ph Values ◽  
Appreciable Increase ◽  
Muscle Ph ◽  
Keeping Quality ◽  
Viable Bacteria

Pacific coast dogfish (Squalus suckleyi) were held 21 days in ice and in refrigerated sea water with and without added chlortetracycline, viable bacterial counts and volatile bases being determined periodically. Viable bacteria increased sharply after about 14 days but the muscle pH values showed little or no increase. No appreciable increase in the total volatile base or trimethylamine content of the muscle was noted until the fish were stored for more than 2 weeks, and then the increases observed were comparatively small.

scholarly journals Sperm cryopreservation of lane snapper Lutjanus synagris(Linnaeus, 1758)

2015 ◽  
Vol 75 (3) ◽  
pp. 662-669 ◽  
Author(s):  
EG Sanches ◽  
IR Oliveira ◽  
PCS Serralheiro ◽  
VR Cerqueira
Keyword(s):  
Sperm Motility ◽  
Sperm Quality ◽  
Equilibration Time ◽  
Dilution Ratio ◽  
Sperm Cryopreservation ◽  
Ph Values ◽  
Cryopreserved Sperm ◽  
Time Density ◽  
Motility Rate

AbstractThis study aims developing and evaluate a protocol of semen cryopreservation of the lane snapper Lutjanus synagris. Firstly, sperm motility rate, motility time, density and spermatocrit were appraised to characterize the sperm quality of the lane snapper. The effect of three extenders with distinct ionic compositions and pH values combined with seven concentrations of cryoprotector dimethylsulfoxide (0; 2.5; 5.0; 7.5; 10.0; 12.5 e 15.0%), five cooling rates (110, 90, 60, 45 e 30°C –min), nine equilibration time (1; 2,5; 5; 10; 15; 20; 25; 30 e 60 minutes) e five dilutions ratio (1:1; 1:3; 1:6; 1:10 e 1:20) on the sperm motility rate and motility time were analyzed. Fertilization test was accomplished to evaluate the viability of the cryopreserved sperm. The higher sperm motility rate and motility time (P<0.05) was achieved by combining extender with pH 8.2 with 10% concentration of dimethylsulfoxide and cooling rate 60°C –min, 1 minute of equilibration time and 1:3 (v/v) dilution ratio. The use of cryopreserved sperm presented fertilization rates >60% validating the present protocol for lane snapper. The cryoconserved sperm of lane snapper is a viable alternative, being possible to maintain appropriate sperm viability.

scholarly journals Concepts for Developing Physical Gels of Chitosan and of Chitosan Derivatives

Gels ◽  
2018 ◽  
Vol 4 (3) ◽  
pp. 67 ◽  
Author(s):  
Pasquale Sacco ◽  
Franco Furlani ◽  
Gaia de Marzo ◽  
Eleonora Marsich ◽  
Sergio Paoletti ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Electrostatic Interactions ◽  
Chitosan Derivatives ◽  
Modified Chitosan ◽  
Physical Chemical ◽  
Degree Of Acetylation ◽  
Potential Applications ◽  
Low Toxicity ◽  
Physical Interactions ◽  
Biomedical Field

Chitosan macro- and micro/nano-gels have gained increasing attention in recent years, especially in the biomedical field, given the well-documented low toxicity, degradability, and non-immunogenicity of this unique biopolymer. In this review we aim at recapitulating the recent gelling concepts for developing chitosan-based physical gels. Specifically, we describe how nowadays it is relatively simple to prepare networks endowed with different sizes and shapes simply by exploiting physical interactions, namely (i) hydrophobic effects and hydrogen bonds—mostly governed by chitosan chemical composition—and (ii) electrostatic interactions, mainly ensured by physical/chemical chitosan features, such as the degree of acetylation and molecular weight, and external parameters, such as pH and ionic strength. Particular emphasis is dedicated to potential applications of this set of materials, especially in tissue engineering and drug delivery sectors. Lastly, we report on chitosan derivatives and their ability to form gels. Additionally, we discuss the recent findings on a lactose-modified chitosan named Chitlac, which has proved to form attractive gels both at the macro- and at the nano-scale.

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