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23 pages, 14535 KiB

Open AccessArticle

The Synthesis of Green Palladium Catalysts Stabilized by Chitosan for Hydrogenation

by Farida Bukharbayeva, Alima Zharmagambetova, Eldar Talgatov, Assemgul Auyezkhanova, Sandugash Akhmetova, Aigul Jumekeyeva, Akzhol Naizabayev, Alima Kenzheyeva and Denis Danilov

Molecules 2024, 29(19), 4584; https://doi.org/10.3390/molecules29194584 - 26 Sep 2024

Viewed by 644

Abstract

The proposed paper describes a simple and environmentally friendly method for the synthesis of three-component polymer–inorganic composites, which includes the modification of zinc oxide or montmorillonite (MMT) with chitosan (CS), followed by the immobilization of palladium on the resulting two-component composites. The structures [...] Read more.

The proposed paper describes a simple and environmentally friendly method for the synthesis of three-component polymer–inorganic composites, which includes the modification of zinc oxide or montmorillonite (MMT) with chitosan (CS), followed by the immobilization of palladium on the resulting two-component composites. The structures and properties of the obtained composites were characterized by physicochemical methods (IRS, TEM, XPS, SEM, EDX, XRD, BET). Pd–CS species covered the surface of inorganic materials through two different mechanisms. The interaction of chitosan polyelectrolyte with zinc oxide led to the deprotonation of its amino groups and deposition on the surface of ZnO. The immobilization of Pd on CS/ZnO occurred by the hydrolysis of [PdCl₄]²⁻, followed by forming PdO particles by interacting with amino groups of chitosan. In the case of CS/MMT, protonated amino groups of CS interacted with negative sites of MMT, forming a positively charged CS/MMT composite. Furthermore, [PdCl₄]²⁻ interacted with the –NH³⁺ sites of CS/MMT through electrostatic force. According to TEM studies of 1%Pd–CS/ZnO, the presence of Pd nanoclusters composed of smaller Pd nanoparticles of 3–4 nm in size were observed on different sites of CS/ZnO. For 1%Pd–CS/MMT, Pd nanoparticles with sizes of 2 nm were evenly distributed on the support surface. The prepared three-component CS–inorganic composites were tested through the hydrogenation of 2-propen-1-ol and acetylene compounds (phenylacetylene, 2-hexyn-1-ol) under mild conditions (T—40 °C, P_H2—1 atm). It was shown that the efficiency of 1%Pd–CS/MMT is higher than that of 1%Pd–CS/ZnO, which can be explained by the formation of smaller Pd particles that are evenly distributed on the support surface. The mechanism of 2-hexyn-1-ol hydrogenation over an optimal 1%Pd–CS/MMT catalyst was proposed. Full article

(This article belongs to the Special Issue Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—2nd Edition)

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21 pages, 4609 KiB

Open AccessArticle

Dye Sorption from Mixtures on Chitosan Sorbents

by Urszula Filipkowska and Tomasz Jóźwiak

Molecules 2024, 29(15), 3602; https://doi.org/10.3390/molecules29153602 - 30 Jul 2024

Viewed by 598

Abstract

This article presents studies on the sorption of the anionic dyes Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84) from solutions of single dyes and from dye mixtures onto three chitosan sorbents–chitin, chitosan DD75% and chitosan DD95%. In this work, the influence [...] Read more.

This article presents studies on the sorption of the anionic dyes Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84) from solutions of single dyes and from dye mixtures onto three chitosan sorbents–chitin, chitosan DD75% and chitosan DD95%. In this work, the influence of pH on sorption efficiency, the sorption equilibrium time for the tested anionic dyes and the sorption capacity in relation to the individual dyes and their mixtures were determined. It has been found that the sorption process for both dyes was most effective at pH 3 for chitin and chitosan DD75 and at pH 4 for chitosan DD95%. The obtained results were described by the double Langmuir equation (Langmuir 2). The obtained constants made it possible to determine the affinity of the tested dyes for the three sorbents and the sorption capacity of the sorbents. For RB5, the highest sorption capacity for chitosan DD95% was achieved with sorption from a single solution–of 742 mg/g DM and with sorption from mixed dyes–of 528 mg/g DM. For RY84, the highest efficiency was also achieved for chitosan DD95% and was 760 mg/g DM for a single dye solution and 437 mg/g DM for a mixture of dyes. Full article

(This article belongs to the Special Issue Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—2nd Edition)

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18 pages, 3528 KiB

Open AccessArticle

Physicochemical Characteristics of Porous Starch Obtained by Combined Physical and Enzymatic Methods—Part 2: Potential Application as a Carrier of Gallic Acid

by Agnieszka Ewa Wiącek and Monika Sujka

Molecules 2024, 29(15), 3570; https://doi.org/10.3390/molecules29153570 - 29 Jul 2024

Viewed by 733

Abstract

Wettability measurements were performed for aqueous dispersions of native and modified corn, potato, and pea starch granules deposited on glass plates by the thin layer method using test liquids of a different chemical nature (polar water and formamide or non-polar diiodomethane). High values [...] Read more.

Wettability measurements were performed for aqueous dispersions of native and modified corn, potato, and pea starch granules deposited on glass plates by the thin layer method using test liquids of a different chemical nature (polar water and formamide or non-polar diiodomethane). High values of the determination coefficient R² confirm that the linear regression model describes the relationship between the wetting time and the square of the penetration distance very well, indicating the linear nature of the Washburn relationship. A change in free energy (enthalpy) during the movement of the liquid in the porous layer was determined for all starches before and after modification in contact with test liquids. Wetting times for polar liquids increased significantly (from 3 to 4 fold), especially for corn starch. The lower the value of the adhesive tension, the easier the wetting process takes place, and consequently, the adsorption process is facilitated. Adhesive tension for polar substances applies to the adsorption of hydrophilic substances, while in the case of apolar substances, adhesive tension applies to the adsorption of hydrophobic substances. For the adsorption of gallic acid on starch, the relationships obtained for polar substances are crucial. The adsorption of gallic acid by forming hydrogen bonds or, more generally, donor–acceptor (acid–base) bonds is definitely higher for corn starch than other starches. Therefore, this starch has the most significant potential for use as a carrier of gallic acid or, more broadly, compounds from the polyphenol group. Full article

(This article belongs to the Special Issue Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—2nd Edition)

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17 pages, 2212 KiB

Open AccessArticle

Chitosan as an Antimicrobial, Anti-Insect, and Growth-Promoting Agent for Potato (Solanum tuberosum L.) Plants

by Aleksandra Steglińska, Adriana Nowak, Regina Janas, Mieczysław Grzesik, Krzysztof Śmigielski, Dorota Kręgiel and Beata Gutarowska

Molecules 2024, 29(14), 3313; https://doi.org/10.3390/molecules29143313 - 13 Jul 2024

Cited by 1 | Viewed by 1311

Abstract

A growing trend in plant protection is replacing chemical preparations with environmentally friendly biological compositions. Chitosan, due to its biocompatibility, biodegradability, and bioactivity, is an effective agent against plant diseases. The purpose of the study was to evaluate chitosan as a potential biopesticide [...] Read more.

A growing trend in plant protection is replacing chemical preparations with environmentally friendly biological compositions. Chitosan, due to its biocompatibility, biodegradability, and bioactivity, is an effective agent against plant diseases. The purpose of the study was to evaluate chitosan as a potential biopesticide for potato plants. Three variants of chitosan were tested: high (310–375 kDa, >75% deacetylated), medium (190–310 kDa, 75–85% deacetylated), and low (50–190 kDa, 75–85% deacetylated) molecular weight. The chitosan variants were dissolved in lactic and succinic acids and tested for antibacterial and antifungal properties against eight strains of mould and two strains of bacteria responsible for potato diseases. The possible cytotoxicity of chitosan was evaluated against different cell lines: insect Sf-9, human keratinocyte HaCaT, and human colon carcinoma Caco-2. The bioprotective activities of the chitosan were also evaluated in situ on potato tubers. Chitosan inhibited the growth of almost all the selected phytopathogens. The most active was medium molecular chitosan in lactic acid. This formula was characterized by low toxicity towards human cells and high toxicity towards Sf-9 cells. It was also found to have positive effects on the growth of stems and roots, gas exchange, and chlorophyll index in potato plants. Selected chitosan formulation was proposed as a functional biopesticide for potato protection against phytopathogens. Full article

(This article belongs to the Special Issue Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—2nd Edition)

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21 pages, 7158 KiB

Open AccessArticle

Chitosan–Surfactant Composite Nanocoatings on Glass and Zinc Surfaces Prepared from Aqueous Solutions

by Péter Márton, Liza Áder, Dávid Miklós Kemény, Adél Rácz, Dorina Kovács, Norbert Nagy, Gabriella Stefánia Szabó and Zoltán Hórvölgyi

Molecules 2024, 29(13), 3111; https://doi.org/10.3390/molecules29133111 - 29 Jun 2024

Viewed by 731

Abstract

Hydrophobic coatings from chitosan–surfactant composites (ca. 400 nm thick by UV-Vis spectroscopy) for possible corrosion protection were developed on glass and zinc substrates. The surfactants (sodium dodecyl sulfate, SDS or sodium dodecylbenzenesulfonate, and SDBS) were added to the chitosan by two methods: mixing [...] Read more.

Hydrophobic coatings from chitosan–surfactant composites (ca. 400 nm thick by UV-Vis spectroscopy) for possible corrosion protection were developed on glass and zinc substrates. The surfactants (sodium dodecyl sulfate, SDS or sodium dodecylbenzenesulfonate, and SDBS) were added to the chitosan by two methods: mixing the surfactants with the aqueous chitosan solutions before film deposition or impregnating the deposited chitosan films with surfactants from their aqueous solutions. For the mixed coatings, it was found that the lower surface tension of solutions (40–45 mN/m) corresponded to more hydrophobic (80–90°) coatings in every case. The hydrophobicity of the impregnated coatings was especially significant (88° for SDS and 100° for SDBS). Atomic force microscopy studies revealed a slight increase in roughness (max 1.005) for the most hydrophobic coatings. The accumulation of surfactants in the layer was only significant (0.8–1.0 sulfur atomic %) in the impregnated samples according to X-ray photoelectron spectroscopy. Polarization and electron impedance spectroscopy tests confirmed better barrier properties for these samples (40–50% pseudo-porosity instead of 94%). The degree of swelling in a water vapor atmosphere was significantly lower in the case of the impregnated coatings (ca. 25%) than that of the native ones (ca. 75%), measured by spectroscopic ellipsometry. Accordingly, good barrier layer properties require advantageous bulk properties in addition to surface hydrophobicity. Full article

(This article belongs to the Special Issue Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—2nd Edition)

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13 pages, 1694 KiB

Open AccessCommunication

Revisiting the Determination of the Degree of Deacetylation Using Potentiometric Titration: A New Equation for Modified Chitosan

by Ons Amamou, Sarah Kefil, Jean-Philippe Denis, Taoufik Boubaker and Sébastien Cardinal

Molecules 2024, 29(13), 2962; https://doi.org/10.3390/molecules29132962 - 21 Jun 2024

Viewed by 1163

Abstract

Chitosan is a biopolymer that can be subjected to a variety of chemical modifications to generate new materials. The properties of modified chitosan are affected by its degree of deacetylation (DDA), which corresponds to the percentage of D-glucosamine monomers in its [...] Read more.

Chitosan is a biopolymer that can be subjected to a variety of chemical modifications to generate new materials. The properties of modified chitosan are affected by its degree of deacetylation (DDA), which corresponds to the percentage of D-glucosamine monomers in its polymeric structure. Potentiometric titration is amongst the simplest, most readily available, and most cost-effective methods of determining the DDA. However, this method often suffers from a lack of precision, especially for modified chitosan resins. This is in large part because the equation used to calculate the DDA does not consider the molecular weight of the chemically modified monomeric units. In this paper, we introduce a new equation that is especially suited for modified chitosan bearing three different types of monomers. To test this equation, we prepared naphthalene–chitosan resins and subjected them to potentiometric titration. Our results show that our new equation, which is truer to the real structure of the polymeric chains, gives higher DDA values than those of the routinely used equations. These results show that the traditional equations underestimate the DDA of modified chitosan resins. Full article

(This article belongs to the Special Issue Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—2nd Edition)

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13 pages, 4299 KiB

Open AccessArticle

Enzymatic Assembly of Chitosan-Based Network Polysaccharides and Their Encapsulation and Release of Fluorescent Dye

by Masayasu Totani, Aina Nakamichi and Jun-ichi Kadokawa

Molecules 2024, 29(8), 1804; https://doi.org/10.3390/molecules29081804 - 16 Apr 2024

Viewed by 886

Abstract

We prepared network polysaccharide nanoscopic hydrogels by crosslinking water-soluble chitosan (WSCS) with a carboxylate-terminated maltooligosaccharide crosslinker via condensation. In this study, the enzymatic elongation of amylose chains on chitosan-based network polysaccharides by glucan phosphorylase (GP) catalysis was performed to obtain assembly materials. Maltoheptaose [...] Read more.

We prepared network polysaccharide nanoscopic hydrogels by crosslinking water-soluble chitosan (WSCS) with a carboxylate-terminated maltooligosaccharide crosslinker via condensation. In this study, the enzymatic elongation of amylose chains on chitosan-based network polysaccharides by glucan phosphorylase (GP) catalysis was performed to obtain assembly materials. Maltoheptaose (Glc₇) primers for GP-catalyzed enzymatic polymerization were first introduced into WSCS by reductive amination. Crosslinking of the product with the above-mentioned crosslinker by condensation was then performed to produce Glc₇-modified network polysaccharides. The GP-catalyzed enzymatic polymerization of the α-d-glucose 1-phosphate monomer from the Glc₇ primers on the network polysaccharides was conducted, where the elongated amylose chains formed double helices. Enzymatic disintegration of the resulting network polysaccharide assembly successfully occurred by α-amylase-catalyzed hydrolysis of the double helical amyloses. The encapsulation and release of a fluorescent dye, Rhodamine B, using the CS-based network polysaccharides were also achieved by means of the above two enzymatic approaches. Full article

(This article belongs to the Special Issue Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—2nd Edition)

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12 pages, 2070 KiB

Open AccessArticle

Isolation, Purification, Fractionation, and Hepatoprotective Activity of Polygonatum Polysaccharides

by Yutong Wang, Hongmei Niu, Yue Ma and Guangxin Yuan

Molecules 2024, 29(5), 1038; https://doi.org/10.3390/molecules29051038 - 28 Feb 2024

Cited by 6 | Viewed by 1425

Abstract

In this study, three homogeneous fractions, PSP-N-b-1, PSP-N-b-2, and PSP-N-c-1, were obtained from an aqueous extract of Polygonatum using DEAE cellulose column chromatography, CL-6B agarose gel chromatography, and Sephadex G100 chromatography. Their monosaccharide compositions and molecular weights were analyzed. The results revealed that [...] Read more.

In this study, three homogeneous fractions, PSP-N-b-1, PSP-N-b-2, and PSP-N-c-1, were obtained from an aqueous extract of Polygonatum using DEAE cellulose column chromatography, CL-6B agarose gel chromatography, and Sephadex G100 chromatography. Their monosaccharide compositions and molecular weights were analyzed. The results revealed that PSP-N-b-1, PSP-N-b-2, and PSP-N-c-1 are primarily composed of six monosaccharides: Man (mannose), GlcA (glucuronic acid), Rha (rhamnose), GalA (galacturonic acid), Glc (glucose), and Ara (arabinose), with molecular weights of 6.3 KDa, 5.78 KDa, and 3.45 KDa, respectively. Furthermore, we observed that Polygonatum polysaccharides exhibited protective effects against CCL₄-induced liver damage in HepG2 cells in vitro, operating through both anti-oxidant and anti-inflammatory mechanisms. Our research findings suggest that Polygonatum polysaccharides may emerge as a promising option in the development of hepatoprotective drugs or functional foods with anti-inflammatory and antioxidant properties. Full article

(This article belongs to the Special Issue Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—2nd Edition)

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14 pages, 1692 KiB

Open AccessArticle

Effect of Acetylation on the Nanofibril Formation of Chitosan from All-Atom De Novo Self-Assembly Simulations

by Aarion Romany, Gregory F. Payne and Jana Shen

Molecules 2024, 29(3), 561; https://doi.org/10.3390/molecules29030561 - 23 Jan 2024

Cited by 2 | Viewed by 1243

Abstract

Chitosan-based materials have broad applications, from biotechnology to pharmaceutics. Recent experiments showed that the degree and pattern of acetylation along the chitosan chain modulate its biological and physicochemical properties; however, the molecular mechanism remains unknown. Here, we report, to the best of our [...] Read more.

Chitosan-based materials have broad applications, from biotechnology to pharmaceutics. Recent experiments showed that the degree and pattern of acetylation along the chitosan chain modulate its biological and physicochemical properties; however, the molecular mechanism remains unknown. Here, we report, to the best of our knowledge, the first de novo all-atom molecular dynamics (MD) simulations to investigate chitosan’s self-assembly process at different degrees and patterns of acetylation. Simulations revealed that 10 mer chitosan chains with 50% acetylation in either block or alternating patterns associate to form ordered nanofibrils comprised of mainly antiparallel chains in agreement with the fiber diffraction data of deacetylated chitosan. Surprisingly, regardless of the acetylation pattern, the same intermolecular hydrogen bonds mediate fibril sheet formation while water-mediated interactions stabilize sheet–sheet stacking. Moreover, acetylated units are involved in forming strong intermolecular hydrogen bonds (NH–O6 and O6H–O7), which offers an explanation for the experimental observation that increased acetylation lowers chitosan’s solubility. Taken together, the present study provides atomic-level understanding the role of acetylation plays in modulating chitosan’s physiochemical properties, contributing to the rational design of chitosan-based materials with the ability to tune by its degree and pattern of acetylation. Additionally, we disseminate the improved molecular mechanics parameters that can be applied in MD studies to further understand chitosan-based materials. Full article

(This article belongs to the Special Issue Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—2nd Edition)

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20 pages, 4865 KiB

Open AccessArticle

Encapsulated Rose Bengal Enhances the Photodynamic Treatment of Triple-Negative Breast Cancer Cells

by Mir Muhammad Nasir Uddin, Alina Bekmukhametova, Anu Antony, Shital K. Barman, Jessica Houang, Ming J. Wu, James M. Hook, Laurel George, Richard Wuhrer, Damia Mawad, Daniel Ta, Herleen Ruprai and Antonio Lauto

Molecules 2024, 29(2), 546; https://doi.org/10.3390/molecules29020546 - 22 Jan 2024

Cited by 2 | Viewed by 2348

Abstract

Among breast cancer subtypes, triple-negative breast cancer stands out as the most aggressive, with patients facing a 40% mortality rate within the initial five years. The limited treatment options and unfavourable prognosis for triple-negative patients necessitate the development of novel therapeutic strategies. Photodynamic [...] Read more.

Among breast cancer subtypes, triple-negative breast cancer stands out as the most aggressive, with patients facing a 40% mortality rate within the initial five years. The limited treatment options and unfavourable prognosis for triple-negative patients necessitate the development of novel therapeutic strategies. Photodynamic therapy (PDT) is an alternative treatment that can effectively target triple-negative neoplastic cells such as MDA-MB-231. In this in vitro study, we conducted a comparative analysis of the PDT killing rate of unbound Rose Bengal (RB) in solution versus RB-encapsulated chitosan nanoparticles to determine the most effective approach for inducing cytotoxicity at low laser powers (90 mW, 50 mW, 25 mW and 10 mW) and RB concentrations (50 µg/mL, 25 µg/mL, 10 µg/mL and 5 µg/mL). Intracellular singlet oxygen production and cell uptake were also determined for both treatment modalities. Dark toxicity was also assessed for normal breast cells. Despite the low laser power and concentration of nanoparticles (10 mW and 5 µg/mL), MDA-MB-231 cells experienced a substantial reduction in viability (8 ± 1%) compared to those treated with RB solution (38 ± 10%). RB nanoparticles demonstrated higher singlet oxygen production and greater uptake by cancer cells than RB solutions. Moreover, RB nanoparticles display strong cytocompatibility with normal breast cells (MCF-10A). The low activation threshold may be a crucial advantage for specifically targeting malignant cells in deep tissues. Full article

(This article belongs to the Special Issue Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—2nd Edition)

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Review

Jump to: Research

53 pages, 15874 KiB

Open AccessReview

How the Chemical Properties of Polysaccharides Make It Possible to Design Various Types of Organic–Inorganic Composites for Catalytic Applications

by Sandugash Akhmetova, Alima Zharmagambetova, Eldar Talgatov, Assemgul Auyezkhanova, Makpal Malgazhdarova, Murat Zhurinov, Arlan Abilmagzhanov, Aigul Jumekeyeva and Alima Kenzheyeva

Molecules 2024, 29(13), 3214; https://doi.org/10.3390/molecules29133214 - 6 Jul 2024

Viewed by 1012

Abstract

Recently, the use of plant-origin materials has become especially important due to the aggravation of environmental problems and the shortage and high cost of synthetic materials. One of the potential candidates among natural organic compounds is polysaccharides, characterized by a number of advantages [...] Read more.

Recently, the use of plant-origin materials has become especially important due to the aggravation of environmental problems and the shortage and high cost of synthetic materials. One of the potential candidates among natural organic compounds is polysaccharides, characterized by a number of advantages over synthetic polymers. In recent years, natural polysaccharides have been used to design composite catalysts for various organic syntheses. This review is devoted to the current state of application of polysaccharides (chitosan, starch, pectin, cellulose, and hydroxyethylcellulose) and composites based on their catalysis. The article is divided into four main sections based on the type of polysaccharide: (1) chitosan-based nanocomposites; (2) pectin-based nanocomposites; (3) cellulose (hydroxyethylcellulose)-based nanocomposites; and (4) starch-based nanocomposites. Each section describes and summarizes recent studies on the preparation and application of polysaccharide-containing composites in various chemical transformations. It is shown that by modifying polysaccharides, polymers with special properties can be obtained, thus expanding the range of biocomposites for catalytic applications. Full article

(This article belongs to the Special Issue Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—2nd Edition)

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