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 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 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.

Transmission Electron Microscopy of Protein Macromolecules

1971 ◽  
Vol 29 ◽  
pp. 424-425
Author(s):  
Henry S. Slayter
Keyword(s):  
Biological Systems ◽  
Metal Vapor ◽  
Resolving Power ◽  
Electron Microscopic ◽  
Chemical Methods ◽  
Molecular Weights ◽  
The Past ◽  
Physical Chemical ◽  
Transmission Electron

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

Solubilization of Itraconazole by Surfactants and Phospholipid-Surfactant Mixtures: Interplay of Amphiphile Structure, pH and Electrostatic Interactions

2020 ◽  
Author(s):  
Zahari Vinarov ◽  
Gabriela Gancheva ◽  
Nikola Burdzhiev ◽  
Slavka S. Tcholakova
Keyword(s):  
Nmr Spectroscopy ◽  
Electrostatic Interactions ◽  
Triazole Ring ◽  
Water Soluble ◽  
Single Chain ◽  
Surfactant Mixtures ◽  
Solubilization Capacity ◽  
Water Soluble Drugs ◽  
Hydrophobic Chain ◽  
Brick Dust

Although surfactants are frequently used in enabling formulations of poorly water-soluble drugs, the link between their structure and drug solubilization capacity is still unclear. We studied the solubilization of the “brick-dust” molecule itraconazole by 16 surfactants and 3 phospholipid:surfactant mixtures. NMR spectroscopy was used to study in more details the drug-surfactant interactions. Very high solubility of itraconazole (up to 3.6 g/L) was measured in anionic surfactant micelles at pH = 3, due to electrostatic attraction between the oppositely charged (at this pH) drug and surfactant molecules. <sup>1</sup>H NMR spectroscopy showed that itraconazole is ionized at two sites (2+ charge) at these conditions: in the phenoxy-linked piperazine nitrogen and in the dioxolane-linked triazole ring. The increase of amphiphile hydrophobic chain length had a markedly different effect, depending on the amphiphile type: the solubilization capacity of single-chain surfactants increased, whereas a decrease was observed for double-chained surfactants (phosphatidylglycerols). The excellent correlation between the chain melting temperatures of phosphatidylglycerols and itraconazole solubilization illustrated the importance of hydrophobic chain mobility. This study provides rules for selection of itraconazole solubilizers among classical single-chain surfactants and phospholipids. The basic physics underpinning the described effects suggests that these rules should be transferrable to other “brick-dust” molecules.

Processing of Iridium Doped Materials and Experimental Investigation of Their Hydrogen Adsorption Capacity

2018 ◽  
Vol 69 (6) ◽  
pp. 1468-1472
Author(s):  
Radu Mirea ◽  
Mihai Iordoc ◽  
Gabriela Oprina ◽  
Gimi Rimbu
Keyword(s):  
Adsorption Capacity ◽  
Hydrogen Adsorption ◽  
Weight Ratio ◽  
H2 Adsorption ◽  
Cyclic Voltametry ◽  
Physical Chemical ◽  
Good Consistency ◽  
Metal Doped ◽  
And Storage ◽  
Poly Aniline

The paper aims to present the investigation of H2 adsorption capacity in metal doped nanostructured materials, by using two methods. Carbonic materials are considered to be one of the most promising materials to be used for hydrogen adsorption and storage. They have different applications and one of the most important is considered to be fuel cells technology. By using metals for doping these materials, the adsorption capacity increases, thus approaching the target of 6.5% weight ratio of H2 adsorbed in a substrate. Within these investigations multi-wall nanotubes and poly-aniline have been used as substrates. The poly-aniline has been prepared and doped in laboratory while the nanotubes used in experiments have been purchased from the market and afterwards doped in laboratory. The doping procedure consists of a physical-chemical method which involves salts of the metal for doping and the use of ultrasounds in order to activate the substrate for doping. The adsorption capacity of the carbonic materials has been determined by using spill over phenomena in a PCT Pro-User apparatus, provided by SETARAM and also by cyclic voltametry, by using VoltaLab-40 apparatus. In order to investigate the adsorption capacity of the nanostructured carbonic materials, the experiments have been carried out at different pressures. Both substrates have been characterized in order to determine their porosity, BET surface and structure. The collected data have been processed by using the PCT Pro-User apparatus�s software. The results have been compared with the available data from literature and a good consistency was found.

scholarly journals Semi-Crystalline Hydrophobic Polyamidoamines: A New Family of Technological Materials?

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1018
Author(s):  
Massimo Marcioni ◽  
Jenny Alongi ◽  
Elisabetta Ranucci ◽  
Mario Malinconico ◽  
Paola Laurienzo ◽  
...  
Keyword(s):  
Maximum Stress ◽  
Water Resistance ◽  
Prolonged Exposure ◽  
Water Soluble ◽  
Synthesis And Characterization ◽  
Molecular Weights ◽  
New Family ◽  
Methylene Groups ◽  
Methane Flame

The hitherto known polyamidoamines (PAAs) are not suitable as structural materials because they are usually water-soluble or swellable in water. This paper deals with the synthesis and characterization of semi-crystalline hydrophobic PAAs (H-PAAs) by combining different bis-sec-amines with bis-acrylamides obtained from C6–C12 bis-prim-amines. H-PAAs were initially obtained in a solution of benzyl alcohol, a solvent suitable for both monomers and polymers. Their number average molecular weights, M¯n, which were determined with 1H-NMR by evaluating the percentage of their terminal units, varied from 6000 to >10,000. The solubility, thermal properties, ignitability and water resistance of H-PAAs were determined. They were soluble in organic solvents, semi-crystalline and thermally stable. The most promising ones were also prepared using a bulk process, which has never been previously reported for PAA synthesis. In the form of films, these H-PAAs were apparently unaffected by water. The films underwent tensile and wettability tests. They showed similar Young moduli (260–263 MPa), whereas the maximum stress and the stress at break depended on the number of methylene groups of the starting bis-acrylamides. Their wettability was somewhat higher than that of common Nylons. Interestingly, none of the H-PAAs considered, either as films or powders, ignited after prolonged exposure to a methane flame.

scholarly journals Solubilization of Charged Porphyrins in Interpolyelectrolyte Complexes: A Computer Study

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 502
Author(s):  
Karel Šindelka ◽  
Zuzana Limpouchová ◽  
Karel Procházka
Keyword(s):  
Dissipative Particle Dynamics ◽  
Water Soluble ◽  
Coarse Grained ◽  
Core Shell ◽  
Computer Study ◽  
Interpolyelectrolyte Complex ◽  
The Core ◽  
Porphyrin Derivatives ◽  
Oppositely Charged ◽  
Positively Charged

Using coarse-grained dissipative particle dynamics (DPD) with explicit electrostatics, we performed (i) an extensive series of simulations of the electrostatic co-assembly of asymmetric oppositely charged copolymers composed of one (either positively or negatively charged) polyelectrolyte (PE) block A and one water-soluble block B and (ii) studied the solubilization of positively charged porphyrin derivatives (P+) in the interpolyelectrolyte complex (IPEC) cores of co-assembled nanoparticles. We studied the stoichiometric mixtures of 137 A10+B25 and 137 A10−B25 chains with moderately hydrophobic A blocks (DPD interaction parameter aAS=35) and hydrophilic B blocks (aBS=25) with 10 to 120 P+ added (aPS=39). The P+ interactions with other components were set to match literature information on their limited solubility and aggregation behavior. The study shows that the moderately soluble P+ molecules easily solubilize in IPEC cores, where they partly replace PE+ and electrostatically crosslink PE− blocks. As the large P+ rings are apt to aggregate, P+ molecules aggregate in IPEC cores. The aggregation, which starts at very low loadings, is promoted by increasing the number of P+ in the mixture. The positively charged copolymers repelled from the central part of IPEC core partially concentrate at the core-shell interface and partially escape into bulk solvent depending on the amount of P+ in the mixture and on their association number, AS. If AS is lower than the ensemble average ⟨AS⟩n, the copolymer chains released from IPEC preferentially concentrate at the core-shell interface, thus increasing AS, which approaches ⟨AS⟩n. If AS>⟨AS⟩n, they escape into the bulk solvent.

Transport of Ions and Molecules in Nanofluidic Devices

2008 ◽  
Author(s):  
Rohit Karnik ◽  
Chuanhua Duan ◽  
Kenneth Castelino ◽  
Rong Fan ◽  
Peidong Yang ◽  
...  
Keyword(s):  
Surface Charge ◽  
Surface Area ◽  
Field Effect ◽  
Electrostatic Interactions ◽  
Surface Reactions ◽  
Molecular Transport ◽  
Large Surface Area ◽  
Ionic Concentrations ◽  
Nanofluidic Devices ◽  
Transport Of Ions

Interesting transport phenomena arise when fluids are confined to nanoscale dimensions in the range of 1–100 nm. We examine three distinct effects that influence ionic and molecular transport as the size of fluidic channels is decreased to the nanoscale. First, the length scale of electrostatic interactions in aqueous solutions becomes comparable to nanochannel size and the number of surface charges becomes comparable to the number of ions in the channel. Second, the size of the channel becomes comparable to the size of biomolecules such as proteins and DNA. Third, large surface area-to-volume ratios result in rapid rates of surface reactions and can dramatically affect transport of molecules through the channel. These phenomena enable us to control transport of ions and molecules in unique ways that are not possible in larger channels. Electrostatic interactions enable local control of ionic concentrations and transport inside nanochannels through field effect in a nanofluidic transistor, which is analogous to the metal-oxide-semiconductor field effect transistor. Furthermore, by controlling surface charge in nanochannels, it is possible to create a nanofluidic diode that rectifies ionic transport through the channel. Biological binding events result in partial blockage of the channel, and can thus be sensed by a decrease in nanochannel conductance. At low ionic concentrations, the effect of biomolecular charge is dominant and it can lead to an increase in conductance. Surface reactions can also be used to control transport of molecules though the channel due to the large surface area-to-volume ratios. Rapid surface reactions enable a new technique of diffusion-limited patterning (DLP), which is useful for patterning of biomolecules and surface charge in nanochannels. These examples illustrate how electrostatic interactions, biomolecular size, and surface reactions can be used for controlling ionic and molecular transport through nanochannels. These phenomena may be useful for operations such as analyte focusing, pH and ionic concentration control, and biosensing in micro- and nanofluidic devices.

scholarly journals Influences of Molecular Weights on Physicochemical and Biological Properties of Collagen-Alginate Scaffolds

Marine Drugs ◽  
2021 ◽  
Vol 19 (2) ◽  
pp. 85 ◽  
Author(s):  
Truc Cong Ho ◽  
Jin-Seok Park ◽  
Sung-Yeoul Kim ◽  
Hoyeol Lee ◽  
Ju-Sop Lim ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Subcritical Water ◽  
Biological Properties ◽  
Ethanol Solution ◽  
Water Soluble ◽  
Potential Candidate ◽  
High Porosity ◽  
Engineering Applications ◽  
Molecular Weights

For tissue engineering applications, biodegradable scaffolds containing high molecular weights (MW) of collagen and sodium alginate have been developed and characterized. However, the properties of low MW collagen-based scaffolds have not been studied in previous research. This work examined the distinctive properties of low MW collagen-based scaffolds with alginate unmodified and modified by subcritical water. Besides, we developed a facile method to cross-link water-soluble scaffolds using glutaraldehyde in an aqueous ethanol solution. The prepared cross-linked scaffolds showed good structural properties with high porosity (~93%) and high cross-linking degree (50–60%). Compared with collagen (6000 Da)-based scaffolds, collagen (25,000 Da)-based scaffolds exhibited higher stability against collagenase degradation and lower weight loss in phosphate buffer pH 7.4. Collagen (25,000 Da)-based scaffolds with modified alginate tended to improve antioxidant capacity compared with scaffolds containing unmodified alginate. Interestingly, in vitro coagulant activity assay demonstrated that collagen (25,000 Da)-based scaffolds with modified alginate (C25-A63 and C25-A21) significantly reduced the clotting time of human plasma compared with scaffolds consisting of unmodified alginate. Although some further investigations need to be done, collagen (25,000 Da)-based scaffolds with modified alginate should be considered as a potential candidate for tissue engineering applications.

FRACTIONATION OF LIVETIN AND THE MOLECULAR WEIGHTS OF THE α- AND β-COMPONENTS

1957 ◽  
Vol 35 (4) ◽  
pp. 241-250 ◽  
Author(s):  
W. G. Martin ◽  
J. E. Vandegaer ◽  
W. H. Cook
Keyword(s):  
Light Scattering ◽  
Soluble Protein ◽  
Soluble Fraction ◽  
Egg Yolk ◽  
Water Soluble ◽  
Water Soluble Fraction ◽  
Molecular Weights ◽  
Water Soluble Protein ◽  
Hen Egg Yolk ◽  
Hen Egg

Livetin, the major water-soluble protein of hen egg yolk, was found to contain three major components having mobilities of −6.3, −3.8, and −2.1 cm.2 sec.−1 volt−1 at pH 8, µ 0.1, and these have been designated α-, β-, and γ-livetin respectively. The α- and β-livetins were separated and purified electrophoretically after removal of γ-livetin by precipitation from 37% saturated ammonium sulphate or 20% isopropanol. The α-, β-, and mixed livetins resembled pseudoglobulins in solubility but γ-livetin was unstable and this loss of solubility has, so far, prevented its characterization. Molecular weights determined by light scattering, osmotic pressure, and Archibald sedimentation procedure yielded respectively: 8.7, 7.8, and 6.7 × 104 for α-livetin, and 4.8, 5.0, and4.5 × 104 for β-livetin. Under suitable conditions of sedimentation and electrophoresis, egg yolk has been shown to contain three components having the same behavior as the three livetins of the water-soluble fraction.

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