scholarly journals An Overview of Current Knowledge on the Properties, Synthesis and Applications of Quaternary Chitosan Derivatives

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2878
Author(s):  
Emanuelle Dantas Freitas ◽  
Celso Fidelis Moura Jr. ◽  
Jonas Kerwald ◽  
Marisa Masumi Beppu
Keyword(s):  
Water Solubility ◽  
Current Knowledge ◽  
Hydroxyl Groups ◽  
Phosphonium Salts ◽  
Experimental Conditions ◽  
Quaternized Chitosan ◽  
Wide Ph Range ◽  
Primary Amino ◽  
Ph Range ◽  
Low Solubility

Chitosan, a chitin-derivative polysaccharide, known for its non-toxicity, biocompatibility and biodegradability, presents limited applications due to its low solubility in neutral or basic pH medium. Quaternization stands out as an alternative to modify this natural polymer, aiming to improve its solubility over a wide pH range and, consequently, expand its range of applications. Quaternization occurs by introducing a quaternary ammonium moiety onto or outside the chitosan backbone, via chemical reactions with primary amino and hydroxyl groups, under vast experimental conditions. The oldest and most common forms of quaternized chitosan involve N,N,N-trimethyl chitosan (TMC) and N-[(2-hydroxy-3-trimethyl ammonium) propyl] chitosan (HTCC) and, more recently, quaternized chitosan by insertion of pyridinium or phosphonium salts. By modifying chitosan through the insertion of a quaternary moiety, permanent cationic charges on the polysaccharide backbone are achieved and properties such as water solubility, antimicrobial activity, mucoadhesiveness and permeability are significantly improved, enabling the application mainly in the biomedical and pharmaceutical areas. In this review, the main quaternized chitosan compounds are addressed in terms of their structure, properties, synthesis routes and applications. In addition, other less explored compounds are also presented, involving the main findings and future prospects regarding the field of quaternized chitosans.

scholarly journals Tuning the Properties of High Molecular Weight Chitosans to Develop Full Water Solubility Within a Wide pH Range

2020 ◽  
Author(s):  
Anderson Fiamingo ◽  
Sergio Paulo Campana Filho ◽  
Osvaldo Novais Oliveira Junior
Keyword(s):  
Molecular Weight ◽  
Biomedical Applications ◽  
Random Distribution ◽  
Water Solubility ◽  
Aqueous Media ◽  
Degree Of Polymerization ◽  
Molecular Weights ◽  
H Nmr ◽  
Wide Ph Range ◽  
Ph Range

<p>The preparation of chitosans soluble in physiological conditions has been sought for years, but so far solubility in non-acidic aqueous media has only been achieved at the expense of lowering chitosan molecular weight. In this work, we applied the multistep ultrasound-assisted deacetylation process (USAD process) to β-chitin and obtained extensively deacetylated chitosans with high molecular weights (Mw ≥ 1,000,000 g mol<sup>-1</sup>). The homogeneous <i>N</i>-acetylation of a chitosan sample resulting from three consecutive USAD procedures allowed us to produce chitosans with a high weight average degree of polymerization (DPw ≈ 6,000) and tunable degrees of acetylation (DA from 5 to 80%). <i>N</i>-acetylation was carried out under mild conditions to minimize depolymerization, while preserving a predominantly random distribution of 2-amino-2-deoxy-D-glucopyanose (<i>GlcN</i>) and 2-acetamido-2-deoxy-D-glucopyanose (<i>GlcNAc</i>) units. This close to random distribution, inferred with deconvolution of nuclear magnetic resonance (<sup>1</sup>H NMR) spectra, is considered as responsible for the solubility within a wide pH range. Two of the highly <i>N</i>-acetylated chitosans (DA ≈ 60 % and ≈ 70 %) exhibited full water solubility even at neutral pH, which can expand the biomedical applications of chitosans. </p>

Preparation and Characterization of 2-Hydroxypropyltrimcthyl Ammonium Chloride Chitosan

2011 ◽  
Vol 183-185 ◽  
pp. 2216-2220
Author(s):  
Zheng Jin ◽  
Kai Zhao ◽  
Gang Chen ◽  
Xu Zhang
Keyword(s):  
Ammonium Chloride ◽  
Water Solubility ◽  
Covalent Binding ◽  
Chemical Properties ◽  
Limiting Factor ◽  
Biological Degradation ◽  
Phagocytic Cells ◽  
Enhance Gene Expression ◽  
Primary Amino ◽  
Ph Range

Chitosan has the potential to act as mediators of DNA transfection targeted to phagocytic cells such as macrophages, and to protect against biological degradation by nucleases as well as enhance gene expression. However, the poor solubility of Chitosan is the major limiting factor in its utilization. 2-hydroxypropyltrimcthyl ammonium chloride Chitosan has be prepared successfully through covalent binding of 2,3-Epoxypropyltrimethylammonium chloride ligands to the polymer’s primary amino groups and the polymer’s structure was verified with FT-IR spectra and NMR spectra. The new polymers were obtained with degree of quaternization (DQ) values around 34%, except in the case of the Phe-derived polymer, and thus possess reduced net positive charge as compared to the parent Chitosan. This study provided the new peptide-Chitosans with full water-solubility over practically the entire physiological pH range and led to more disordered. Globally, the new peptide Chitosans and especially the Asp-derived polymer, possess physico-chemical properties that turn them into promising candidates as novel Chitosan-based vaccine delivery systems.

scholarly journals A Comparison Study on Fluorescence Properties of Formononetin and Ononin

2021 ◽  
Author(s):  
Jinjin Cao ◽  
Fang Lv ◽  
Ting Liu ◽  
Luchen Niu ◽  
Bocong Han ◽  
...  
Keyword(s):  
Fluorescence Enhancement ◽  
Alkaline Condition ◽  
Excitation Wavelength ◽  
Comparison Study ◽  
Spectral Difference ◽  
Experimental Conditions ◽  
Pyrone Ring ◽  
Wide Ph Range ◽  
Alkaline Conditions ◽  
Ph Range

Abstract In this work, reasons for the spectral difference between two isoflavones, Formononetin (F) and ononin (FG), are explained in the viewpoint of molecular structure through a comparison study of the fluorescence features of the two. The fluorescence enhancement of FG in hot alkaline condition is reported for the first time. For F, there was almost no fluorescence under acidic conditions, but when pH>5, its fluorescence began to increase with increasing pH due to the proton ionization of 7-OH. In the range of pH 9.3-12.0, the anion form of F produced a fairly strong and stable fluorescence with maximum excitation wavelength (λex) of 334 nm and emission wavelength (λem) of 464 nm, its fluorescence quantum yield (Yf) was measured to be 0.042. And for FG, its aqueous solution fluoresced weakly in a wide pH range until it was placed under hot alkaline conditions, which was presumed to the cleavage reaction of the γ-pyrone ring in FG by observing a significant fluorescence at λex / λem =288 / 388nm, and Yf was determined to be 0.020. The fluorescence sensitization methods of F and FG both exhibit low limits of detection (2.60 ng·mL-1, 9.30 ng·mL-1) and wide linear ranges (0.0117-1.86 μg·mL-1, 0.0146-2.92μg·mL-1). Although the structural relationship between F and FG is glycoside and aglycone, FG cannot be translated to F by glucoside hydrolysis under hot alkaline condition, the fluorescence enhancement mechanisms of the two are essentially different. The fluorescence difference between the two under different experimental conditions lays the foundation for future fluorescence quantitative analysis.

scholarly journals Amyloid formation of bovine insulin is retarded in moderately acidic pH and by addition of short-chain alcohols

2020 ◽  
Vol 49 (2) ◽  
pp. 145-153 ◽  
Author(s):  
David Bernson ◽  
Almedina Mecinovic ◽  
Md Tuhin Abed ◽  
Fredrik Limé ◽  
Per Jageland ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
Current Knowledge ◽  
Solvent Polarity ◽  
Bovine Insulin ◽  
Short Chain ◽  
Amyloid Formation ◽  
Wide Ph Range ◽  
Model Protein ◽  
Ph Range ◽  
Simplistic Model

AbstractProtein aggregation and amyloid formation are associated with multiple human diseases, but are also a problem in protein production. Understanding how aggregation can be modulated is therefore of importance in both medical and industrial contexts. We have used bovine insulin as a model protein to explore how amyloid formation is affected by buffer pH and by the addition of short-chain alcohols. We find that bovine insulin forms amyloid fibrils, albeit with different rates and resulting fibril morphologies, across a wide pH range (2–7). At pH 4.0, bovine insulin displayed relatively low aggregation propensity in combination with high solubility; this condition was therefore chosen as basis for further exploration of how bovine insulin’s native state can be stabilized in the presence of short-chain alcohols that are relevant because of their common use as eluents in industrial-scale chromatography purification. We found that ethanol and isopropanol are efficient modulators of bovine insulin aggregation, providing a three to four times retardation of the aggregation kinetics at 30–35% (vol/vol) concentration; we attribute this to the formation of oligomers, which we detected by AFM. We discuss this effect in terms of reduced solvent polarity and show, by circular dichroism recordings, that a concomitant change in α-helical packing of the insulin monomer occurs in ethanol. Our results extend current knowledge of how insulin aggregates, and may, although bovine insulin serves as a simplistic model, provide insights into how buffers and additives can be fine-tuned in industrial production of proteins in general and pharmaceutical insulin in particular.

Ultra long-term cellular tracing by a fluorescent AIE bioconjugate with good water solubility over a wide pH range

2017 ◽  
Vol 5 (25) ◽  
pp. 4981-4987 ◽  
Author(s):  
Zhengke Wang ◽  
Ling Yang ◽  
Yalan Liu ◽  
Xiaofei Huang ◽  
Fenghui Qiao ◽  
...  
Keyword(s):  
Water Solubility ◽  
Cell Tracing ◽  
Wide Ph Range ◽  
Ph Range

TPE-NSCS, which displayed an AIE effect, could be solubilized in water over a wide pH range, and used in cell tracing for 30 passages.

scholarly journals Tuning the Properties of High Molecular Weight Chitosans to Develop Full Water Solubility Within a Wide pH Range

2020 ◽  
Author(s):  
Anderson Fiamingo ◽  
Sergio Paulo Campana Filho ◽  
Osvaldo Novais Oliveira Junior
Keyword(s):  
Molecular Weight ◽  
Biomedical Applications ◽  
Random Distribution ◽  
Water Solubility ◽  
Aqueous Media ◽  
Degree Of Polymerization ◽  
Molecular Weights ◽  
H Nmr ◽  
Wide Ph Range ◽  
Ph Range

<p>The preparation of chitosans soluble in physiological conditions has been sought for years, but so far solubility in non-acidic aqueous media has only been achieved at the expense of lowering chitosan molecular weight. In this work, we applied the multistep ultrasound-assisted deacetylation process (USAD process) to β-chitin and obtained extensively deacetylated chitosans with high molecular weights (Mw ≥ 1,000,000 g mol<sup>-1</sup>). The homogeneous <i>N</i>-acetylation of a chitosan sample resulting from three consecutive USAD procedures allowed us to produce chitosans with a high weight average degree of polymerization (DPw ≈ 6,000) and tunable degrees of acetylation (DA from 5 to 80%). <i>N</i>-acetylation was carried out under mild conditions to minimize depolymerization, while preserving a predominantly random distribution of 2-amino-2-deoxy-D-glucopyanose (<i>GlcN</i>) and 2-acetamido-2-deoxy-D-glucopyanose (<i>GlcNAc</i>) units. This close to random distribution, inferred with deconvolution of nuclear magnetic resonance (<sup>1</sup>H NMR) spectra, is considered as responsible for the solubility within a wide pH range. Two of the highly <i>N</i>-acetylated chitosans (DA ≈ 60 % and ≈ 70 %) exhibited full water solubility even at neutral pH, which can expand the biomedical applications of chitosans. </p>

scholarly journals Novel nanostructured Fe–Cu–Al trimetal oxide for enhanced antimony(V) removal: synthesis, characterization and performance

2019 ◽  
Vol 79 (10) ◽  
pp. 1995-2004
Author(s):  
Jianyan Wang ◽  
Jing Chen ◽  
Qiumei Li ◽  
Gaosheng Zhang
Keyword(s):  
Toxic Metal ◽  
Point Of Zero Charge ◽  
Precipitation Method ◽  
Hydroxyl Groups ◽  
Adverse Health Effects ◽  
Ion Exchange Reaction ◽  
Wide Ph Range ◽  
And Performance ◽  
Ph Range ◽  
Co Precipitation

Abstract Given the adverse health effects of antimony (Sb), there is an increased focus on developing methods to remove this toxic metal from contaminated water bodies. To effectively remove Sb(V), a new nanostructured Fe–Cu–Al trimetal oxide was fabricated using co-precipitation method at ambient temperature. The Fe–Cu–Al trimetal oxide was very effective at removing Sb(V) from water; it had a maximal adsorption capacity of 169.1 mg/g at pH 7.0, a capacity that was competitive with most other reported adsorbents. The obtained amorphous oxide had a high pH point of zero charge (pHpzc = 8.8) and good adsorption Sb(V) efficiency over a wide pH range (4.0–8.0). Sb(V) uptake was achieved mainly through an ion-exchange reaction between Sb(V) ions and hydroxyl groups on the surface of the oxide. Given its good removal performance, high selectivity, and simple synthesis, this novel Fe–Cu–Al trimetal oxide offers a promising alternate for removing antimony contamination from aquatic environments.

scholarly journals Photocatalytic Degradation of Rhodamine B in Heterogeneous and Homogeneous Systems

2021 ◽  
Vol 49 (1) ◽  
pp. 9-16
Author(s):  
Asfandyar Khan ◽  
Zsolt Valicsek ◽  
Ottó Horváth
Keyword(s):  
Photocatalytic Degradation ◽  
Rhodamine B ◽  
Reaction Rate ◽  
Vibrio Fischeri ◽  
Antibacterial Property ◽  
Copper Ferrite ◽  
Experimental Conditions ◽  
Wide Ph Range ◽  
Bioluminescence Assay ◽  
Ph Range

This study focuses on the photocatalytic degradation of Rhodamine B (RhB) in heterogeneous and homogeneous photo-Fenton reactions. In the heterogeneous system, iron(II) doped copper ferrite CuII(x)FeII(1-x)FeIII2O4 nanoparticles (NPs) prepared in our previous work were employed as potential catalysts. The photodegradation of RhB was carried out in a quartz cuvette located in a diode array spectrometer. The experimental conditions such as pH, NPs dosage and H2O2 dosage with regard to the photocatalytic degradation of RhB were optimized to be 7.5, 500 mg/L and 8.9x10-2 mol/L, respectively. In addition, visible light-induced photodegradation of RhB was also carried out by using \ch{H2O2} over a wide pH range in the absence of heterogeneous photocatalysts. It was observed that the reaction rate significantly increased above pH 10, resulting in a faster rate of degradation of RhB, which may be attributed to the deprotonation of hydrogen peroxide. Furthermore, the potential antibacterial property of such catalysts against the Gram-negative bacterium Vibrio fischeri in a bioluminescence assay yielded inhibition activities of more than 60% in all cases.

scholarly journals Anion Permeability of Frog Skeletal Muscle

1969 ◽  
Vol 54 (1) ◽  
pp. 33-52 ◽  
Author(s):  
L. E. Moore
Keyword(s):  
Relative Proportion ◽  
Chloride Concentration ◽  
Bathing Solution ◽  
Constant Field ◽  
Chloride Permeability ◽  
Equilibrium Conditions ◽  
Experimental Conditions ◽  
Permeability Constant ◽  
Wide Ph Range ◽  
Ph Range

Unidirectional chloride effluxes from small bundles of muscle fibers were measured under equilibrium conditions. It was found that chloride effluxes are described by the constant field theory with a chloride permeability constant, Pcl, which is independent of the chloride concentration and the membrane potential. The value of Pcl at neutral pH was found to be 5 x 10-6 cm/sec. Chloride movements were markedly depressed at low pH and increased at high pH. It is concluded that chloride fluxes are independent of each other over a wide pH range. The effect of nitrate on the chloride effluxes was measured. It was found that both external and internal nitrate alone reduced the chloride efflux with the external nitrate appearing more effective than internal nitrate due to the nonequilibrium nature of the experimental conditions. Under equilibrium conditions the reduction of the chloride efflux by nitrate was greater than the external nitrate effect, both of which were dependent on the relative proportion of nitrate in the bathing solution. These results are consistent with the hypothesis that the inhibition of the chloride movements by nitrate is essentially symmetrical with regard to the inside and outside surfaces of the muscle membranes. The relative action of nitrate on the chloride efflux was independent of the external pH despite marked changes in the absolute values of the fluxes measured.

Polarographic and spectrophotometric behaviour of some N-p-phenyl substituted benzamidines

1991 ◽  
Vol 56 (12) ◽  
pp. 2791-2799 ◽  
Author(s):  
Juan A. Squella ◽  
Luis J. Nuñez-Vergara ◽  
Hernan Rodríguez ◽  
Amelia Márquez ◽  
Jose M. Rodríguez-Mellado ◽  
...  
Keyword(s):  
Spectrophotometric Study ◽  
Absorption Bands ◽  
Electrochemical Parameters ◽  
Wide Ph Range ◽  
Group A ◽  
Substituent Constants ◽  
Ph Range ◽  
The Waves

Five N-p-phenyl substituted benzamidines were studied by DC and DP polarography in a wide pH range. Coulometric results show that the overall processes are four-electron reductions. Logarithmic analysis of the waves indicate that the process are irreversible. The influence of the pH on the polarographic parameters was also studied. A UV spectrophotometric study was performed in the pH range 2-13. In basic media some variations in the absorption bands were observed due to the dissociation of the amidine group. A determination of the pK values was made by deconvolution of the spectra. Correlations of both the electrochemical parameters and spectrophotometric pK values with the Hammett substituent constants were obtained.

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