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Introduction of Chitosan as Nano-drug Delivery Carrier
Chitin is the second largest natural polymer after cellulose, and it exists widely in nature, such as shells of crustaceans such as shrimps, crabs, insects, and cell walls of fungi. Although chitin has good biocompatibility and biodegradability, its poor solubility limits its practicality in the field of biomedicine. The product of chitin deacetylation is chitosan. Chitosan is structurally composed of D-glucosamine units, and each repeating glycoside unit has an amino group (-NH2) and two hydroxyl groups (-OH). The -NH2 group in the chitosan structural unit will be protonated to form -NH3+ ions in an acidic environment, and the free active amino group (-NH2) in the chitosan structure provides the easy…
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Advantages of Heparin as a Nano-Drug Carrier Material
Natural polysaccharides have the characteristics of high safety, good stability and degradability, and are easy to be chemically modified and modified, such as heparin, chitosan, hyaluronic acid and hydroxyethyl starch, and are widely used in nano-drug delivery systems. However, chitosan has poor water solubility and needs to be modified with polyethylene glycol; although hyaluronic acid can improve the selectivity of drugs to tumor cells, it is easy to accumulate in the liver and kidney and cause toxic side effects. Both hydroxyethyl starch and heparin have good hydrophilicity and biocompatibility, but heparin also has its unique natural advantages: 1. Inhibition of angiogenesis-mediated anti-tumor activity; 2. Anti-tumor metastasis activity; 3. Tumor targeting.…
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What Are Heparins?
Heparin, also known as standard heparin or unfractionated heparin, is a linear polysaccharide consisting of 1-4 linked disaccharide repeat units of uronic acid and glucosamine residues. Heparin was discovered nearly 100 years ago and has been used clinically as a blood anticoagulant since 1935. This is due to its ability to bind to the antithrombin(serine protease inhibitor), causing the inhibitor to inactivate thrombin. How to Get Heparin? Heparin is a naturally occurring polysaccharide which contains a highly sulfated glycosaminoglycan framework. It is found in animal tissues in form of heparin sulphate. Unfractionated heparins are usually isolated from natural tissues such as pig intestine or bovine lung, with an average molecular…
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Sucrose Polymer Overview
Sucrose is a disaccharide with a unique structure. It is a non-reducing sugar formed by removing a molecule of water from the glycoside hydroxyl group of a molecule of α-D-(+)-glucopyranose and a molecule of β-D-(-)-fructofuranose. During the hydrolysis process, the specific optical rotation of sucrose gradually changes from dextrorotatory to levorotatory, so the hydrolysis of sucrose is also commonly referred to as a conversion reaction. There are 8 chemically active hydroxyl groups and glycosidic bonds in the sucrose molecule, through which these groups can theoretically undergo oxidation, reduction, decomposition, esterification, polycondensation, etherification, substitution, degradation, etc. with other compounds or itself. This reaction provides the possibility to form a wide variety…
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What Are D-Glucosamines?
Glucosamine is a natural component of cartilage and is widely used as an over-the-counter nutritional supplement to reduce the pain and cartilage loss of osteoarthritis. Glucosamine is usually taken in combination with chondroitin, which is a glycosaminoglycan that also exists in cartilage. Glucosamine is an amino sugar and an important molecule in the biochemical pathway of glycosylated protein and lipid synthesis. It is also the main component of keratin sulfate and hyaluronic acid present in articular cartilage and synovial fluid. Both glucosamine and chondroitin are reduced in osteoarthritis. Clinically, active supplementation of glucosamine and chondroitin can relieve the symptoms of arthritis. Therefore, it is widely used to treat osteoarthritis and…
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Research on Metal Nanoclusters in the Field of Biomedicine
Due to the excellent characteristics of metal nanoclusters, they have many applications in the field of biomedicine. Current research shows that metal nanoclusters have good application value in biosensors, nucleic acid and protein molecular detection. Application of Metal Nanoclusters in Biosensing Metal nanoclusters have excellent fluorescence and catalytic properties, and are ideal fluorescent and chromatic signal probes. At the same time, the specific interaction between metal nanoclusters and analytes can cause the change of metal cores, ligand shells or the surrounding microenvironment. The change causes a change in performance. Therefore, the metal nanoclusters integrate the identification element and the signal conversion element as a whole, and the biosensor constructed therefrom…
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What are Metal Nanoclusters
Metal nanoclusters are a kind of nanomaterials with a size of less than 2 nm and stacked by 1 to 150 metal atoms. Metal nanoclusters have a typical core-shell structure, consisting of a metal atomic core and a ligand molecular shell. Ligands are usually substances that have strong covalent interaction with metal atoms such as amino groups, sulfhydryl groups, and phosphorus groups, such as thiol compounds, dendrimers, polymers, deoxyribonucleic acid (DNA), polypeptides, and proteins. At present, gold nanoclusters (AuNCs), silver nanoclusters (AgNCs), platinum nanoclusters (PtNCs), copper nanoclusters (CuNCs) and other metal nanoclusters have been widely synthesized. In recent years, metal nanoclusters have made remarkable achievements in biomedical fields such as…
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What Are Dextrans?
Dextran is a polysaccharide comprised of d-glucopyranose (d-glucose) repeating units linked through glycosidic linkages. It is biocompatible, biodegradable, and presents antithrombotic and anti-inflammatory properties. Dextran functional hydroxyl (–OH) groups offer an easy point for chemical conjugation with other materials. As an example, dextran can be modified with hydrophobic moieties in order to form dextran-based amphiphiles. These amphiphilic materials can encapsulate poorly water-soluble chemotherapeutics through hydrophobic interactions and self-assemble into nanocarriers. What Are the Chemical Structure and Properties of Dextrans? Dextran consists of α(1,6)-linked glucan with side chains attached to the C-3 position of the backbone (Figure 1). It is synthesized from sucrose by certain lactic acid bacteria, such as leuconostoc…
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What Is Polylactide?
Polylactide (PLA), also the polylactic acid, is the biodegradable hydrolyzable aliphatic semicrystalline polyester that can be produced through the direct condensation reaction of its monomer, lactic acid, as the oligomer, and also by a ring-opening polymerization of the cyclic lactide dimer. Is Polylactic Acid Natural? PLA is a biodegradable, biocompatible, and renewable thermoplastic polyester. The monomer lactic acid (LA) of PLA is derived from natural sources, which is produced using bacterial fermentation of corn, sugarcane, potatoes, sugar beet pulp, and other biomass. What Are the Characteristics of Polylactide? PLA is a very useful material to be used as a replacement for petroleum-based polymers because of its good mechanical properties and…
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What Are Macrocycles?
Macrocycles are generally described as molecules and ions containing twelve- or more-membered rings. Macrocyclic compounds describe a large and mature field of chemistry. The macrocycle often binds ions and facilitates the transport of ions across the hydrophobic membrane and solvent. It wraps the ions with a hydrophobic sheath, which facilitates the phase transfer characteristics. What Are Macrocyclic Effects? The macrocyclic effect is when the multidentate ligand forms a ring with the central metal atom or ion, since it is a multidentate ligand, the stability of the complex is enhanced. The macrocyclic effect is the high affinity of metal cations for macrocyclic ligands compared to their acyclic analogs. What Is a…
