Curdlan is a bacterial polysaccharide that has been of significant recent interest due to its interesting and valuable rheological properties and its inherent bioactivity. The simple (1→3)-β-glucan ...homopolymeric, unbranched structure of curdlan is conducive to enhanced solubility relative to many other abundant natural polysaccharides, thus, providing alternatives for processing the polymer into desired shapes and formulations. At the same time, this relatively good solubility enables chemical modification under mild conditions, leading to a growing body of literature on derivative chemistry, structure–property relationships, and the potential for regioselective modification. Structure, properties, biosynthesis, modification chemistries, and key applications are the foci for this review of the curdlan literature.
Polysaccharide chemistry is enjoying accelerating development thanks to advances in synthetic techniques, biochemistry and solvents, which enable polysaccharide materials to be useful in a variety of ...demanding applications. Among the synthetic advances, click chemistry has reconfigured the realm of polysaccharide modification that previously was dominated by conventional synthetic approaches such as esterification and etherification. “Click” reactions provide mild, modular, and efficient modification pathways, and equally importantly allow us to synthesize derivatives with novel functionality, architecture, and properties, that are otherwise difficult to obtain via conventional methods. Herein, we review application in polysaccharide modification of six groups of click reactions; CuAAC (copper catalyzed alkyne/azide cycloaddition), metal-free 3+2 cycloaddition, Diels–Alder reaction, oxime click, thiol-Michael reaction, and thiol-ene reaction, as well as one click-like reaction that is the subject of our own research, olefin cross-metathesis.
Display omitted
•Research progress of antibacterial modification of Lyocell fiber reviewed.•Characteristics, advantages, drawbacks of antibacterial Lyocell preparation methods described.•Remaining ...issues related to antibacterial Lyocell preparation discussed, future prospects proposed.
As the most successful regenerated cellulose fiber developed in recent decades, Lyocell has attracted much attention due to its useful properties, simple manufacturing process, and recyclable solvent. However, Lyocell’s lack of antibacterial properties limits its application in medical and health fields. Antibacterial modification of Lyocell fiber can be achieved by three general approaches: physical blending, chemical reaction, and post-treatment. Physical blending methods introduce antibacterial agents directly into the spinning dope. In chemical reaction methods, functional groups of the antibacterial additives are grafted or crosslinked into Lyocell fibers, thereby imparting antimicrobial properties. In post-treatment methods, antibacterial additives are deposited on Lyocell fiber surfaces by physical coating, padding, or impregnation processes. We organize our review of antibacterial modification of Lyocell fibers by these preparation methods. Some of the modified Lyocell fibers are reported to exhibit improved antimicrobial activity against various bacteria and fungi, indicating promise for application in medical or hygienic products.
Abstract Alginates have become an extremely important family of polysaccharides because of their utility in preparing hydrogels at mild pH and temperature conditions, suitable for sensitive ...biomolecules like proteins and nucleic acids, and even for living cells such as islets of Langerhans. In addition, the complex monosaccharide sequences of alginates, and our growing ability to create controlled sequences by the action of isolated epimerases upon the alginate precursor poly(mannuronic acid), create remarkable opportunities for understanding the relationship of properties to sequence in natural alginates (control of monosaccharide sequence being perhaps the greatest synthetic challenge in polysaccharide chemistry). There is however a trend in recent years to create “value-added” alginates, by performing derivatization reactions on the polysaccharide backbone. For example, chemical derivatization may enable alginates to achieve enhanced hydroxyapatite (HAP) nucleation and growth, heparin-like anticoagulation properties, improved cell–surface interactions, degradability, or tuning of the hydrophobic-hydrophilic balance for optimum drug release. The creation of synthetic derivatives therefore has the potential to empower the next generation of applications for alginates. Herein we review progress towards controlled synthesis of alginate derivatives, and the properties and applications of these derivatives.
Cellulose ethers have proven to be highly useful natural-based polymers, finding application in areas including food, personal care products, oil field chemicals, construction, paper, adhesives, and ...textiles. They have particular value in pharmaceutical applications due to characteristics including high glass transition temperatures, high chemical and photochemical stability, solubility, limited crystallinity, hydrogen bonding capability, and low toxicity. With regard to toxicity, cellulose ethers have essentially no ability to permeate through gastrointestinal enterocytes and many are already in formulations approved by the U.S. Food and Drug Administration. We review pharmaceutical applications of these valuable polymers from a structure–property–function perspective, discussing each important commercial cellulose ether class; carboxymethyl cellulose, methyl cellulose, hydroxypropylcellulose, hydroxypropyl methyl cellulose, and ethyl cellulose, and cellulose ether esters including hydroxypropyl methyl cellulose acetate succinate and carboxymethyl cellulose acetate butyrate. We also summarize their syntheses, basic material properties, and key pharmaceutical applications.
Polysaccharides comprise an important class of natural polymers; they are abundant, diverse, polyfunctional, typically benign, and are biodegradable. Using polysaccharides to design in situ forming ...hydrogels is an attractive and important field of study since many polysaccharide-based hydrogels exhibit desirable characteristics including self-healing, responsiveness to environmental stimuli, and injectability. These characteristics are particularly useful for biomedical applications. This review will discuss recent discoveries in polysaccharide-based in situ forming hydrogels, including network architecture designs, curing mechanisms, physical and chemical properties, and potential applications.
Polysaccharides are biodegradable, abundant, sustainable, and often benign natural polymers. The achievement of selective modification of polysaccharides is important for targeting specific ...properties and structures and will benefit future development of highly functional, sustainable materials. The synthesis of polysaccharides containing aldehyde or ketone moieties is a promising tool for achieving this goal because of the rich chemistry of aldehyde or ketone groups, including Schiff base formation, nucleophilic addition, and reductive amination. The obtained polysaccharide aldehydes or ketones themselves have rich potential for making useful materials, such as self-healing hydrogels, polysaccharide–protein therapeutic conjugates, or drug delivery vehicles. Herein, we review recent advances in synthesizing polysaccharides containing aldehyde or ketone moieties and briefly introduce their reactivity and corresponding applications.
Staudinger reactions are frequently highly chemoselective and can occur under very mild conditions, so are attractive methods for efficient functionalization of polysaccharides. This review describes ...recent investigations that exploit Staudinger-related reactions to effectively alter physical and chemical properties of polysaccharides in order to make them more diversely applicable. Staudinger-related reactions, such as Staudinger reduction, Staudinger ligation, and traceless Staudinger ligation comprise a powerful family of techniques enabling preparation of a wide range of polysaccharide derivatives with excellent chemoselectivity and the potential for excellent regioselectivity when combined with other methods. The remarkably mild conditions of the Staudinger reactions, combined with the abiotic nature of the azide group, make these reactions exceptionally attractive for modification of intact biological entities, including living cells.
Polysaccharides are abundant natural polymers, which in nature are at times covalently modified with peptides and proteins. Polysaccharide–protein or polysaccharide–peptide conjugates, natural or ...otherwise, may have increased solubility, improved emulsion properties, prolonged circulation time, reduced immunogenicity, and enhanced selectivity for targeting specific tissues compared to native peptides and proteins. In this paper, we will review recent advances in synthetic methods for producing polysaccharide–protein conjugates and discuss their advantages with a focus on drug targeting.
Display omitted
•Advances in chemical synthesis of polysaccharide-protein conjugates reviewed•Enhanced properties of polysaccharide-protein conjugates described•Challenges in synthetic methods discussed
Site-specific conjugation of polysaccharides with proteins is very challenging. Creating the ability to control chemo- and regioselective reaction between polysaccharides and amino acid derivatives ...can not only create potentially useful and bioactive natural polymer constructs, but should also provide useful guidance for the principles of polysaccharide–protein conjugate synthesis. In this work, we exploited regioselective bromination of the non-reducing end primary dextran hydroxyl using N-bromosuccinimide (NBS) and triphenylphosphine (Ph3P) in the dimethylacetamide (DMAc) and lithium bromide solvent system, thereby enabling a regio- and chemoselective synthetic strategic approach to a variety of polysaccharide-amino acid ester adducts. We demonstrated selective condensation of the α-amino groups of esters of the amino acids tyrosine and proline, displacing the single, terminal C6 bromides of 6-BrDextran, as well as the 6-Br moieties of 6-BrCA320S, with high conversion (71–96%). Histidine ester side group amines were found to react with 6-BrCA320S, while those of tryptophan ester did not. These results provide useful access to polysaccharide–amino acid ester adducts of various architectures, and guide us in designing new pathways to polysaccharide–protein copolymers.
Display omitted
PDF
