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Glycan-Based Nanocarriers in Drug Delivery
Published in Raj K. Keservani, Anil K. Sharma, Rajesh K. Kesharwani, Drug Delivery Approaches and Nanosystems, 2017
Songul Yasar Yildiz, Merve Erginer, Tuba Demirci, Juergen Hemberger, Ebru Toksoy Oner
Glycans can be defined as “compounds consisting of a large number of monosaccharides linked glycosidically” (Panitch et al., 2014). These polymeric molecules can be homopolysaccharides or heteropolysaccharides of monomeric sugar residues, and can be either branched or linear. Moreover, the term glycan can be used for the sugar part of a glycoconjugate (glycolipid, glycoprotein and proteoglycan), even though the carbohydrate is only an oligosaccharide (Dwek, 1996). In glycoproteins, there are two types of linkages between oligosasaccharides and proteins. The first type, called N-linked glycans, includes the binding of N-acetylglucosamine to the amide side chain of asparagine. The second type, O-linked glycans, contains the binding of C-1 of N-acetylgalactosamine to the hydroxyl function of serine or threonine (Gorelik et al., 2001).
The roadmap towards cure of chronic hepatitis B virus infection
Published in Journal of the Royal Society of New Zealand, 2022
Because siRNAs and ASOs will be digested if administered orally, they must be delivered parenterally with the associated risk of off-target toxicities. The earliest attempts to develop a liver-targeting delivery system were through liver-tropic cholesterol-conjugated siRNAs (ARC-520/521) or siRNAs packaged within lipid nanoparticles (ARB-1467/1740; ALN-HBV). Both delivery systems required intravenous administration which was associated with frequent and severe infusion reactions necessitating complex premedication protocols. In addition, the frequency of IV dosing needed to be at least weekly to avoid virologic rebound between doses. These unwanted off-target effects were reduced by conjugating the siRNA with N-acetylgalactosamine (GalNAc), thereby enhancing hepatocyte uptake via Asialoglycoprotein Receptor (ASGPR). These newer liver-targeting formulations can be administered subcutaneously without premedication. Patient tolerability is improved by less side effects and longer dosing intervals (at least monthly or less frequently).
A human pericardium biopolymeric scaffold for autologous heart valve tissue engineering: cellular and extracellular matrix structure and biomechanical properties in comparison with a normal aortic heart valve
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Frantisek Straka, David Schornik, Jaroslav Masin, Elena Filova, Tomas Mirejovsky, Zuzana Burdikova, Zdenek Svindrych, Hynek Chlup, Lukas Horny, Matej Daniel, Jiri Machac, Jelena Skibová, Jan Pirk, Lucie Bacakova
GAGs are formed from long unbranched chains of repeating disaccharides (N-acetylglucosamine or N-acetylgalactosamine and either uronic acid or galactose). Proteoglycans are formed when GAGs are connected by covalent linkage to a protein core [58]. GAGs (hyaluronan, heparin sulfate, chondroitin sulfate, dermatan sulfate, keratin sulfate) and proteoglycans (decorin, biglycan, versican) were found in all layers, but preferentially in the lamina spongiosa of the NAV leaflets. GAGs connected to fiber-fiber and fiber-matrix interactions at low force levels are able to hydrate the spongiosa layer by binding water molecules by negatively-charged sulfated and carboxylated polysaccharides, and they provide viscoelasticity by dampening the vibrations. In this way, GAGs allow for the compressibility of the leaflets and permit changes in the arrangement of the collagen and of the elastic fibers in the NAV leaflet during cuspal flexure [56,59,60]. GAGs were found uniformly in all layers of the fibrous HP, but in higher amounts in the inner serosal part.
Antibody separation using lectin modified poly(HEMA-EDMA) hydrogel membranes
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Esra Feyzioğlu Demir, Cansu Ilke Kuru, Murat Uygun, Deniz Aktaş Uygun, Sinan Akgöl
One most widely used affinity chromatography techniques for biomolecules separations is lectin affinity chromatography. In this chromatographic method, various lectin molecules are used as a ligand molecule [24]. Lectin proteins have high affinity and selectivity towards to carbohydrates and carbohydrate bearing molecules [25]. In addition, despite its high specificity toward carbohydrate bearing biomolecules, bonded molecules can be easily eluted by washing with a solution containing a competitive carbohydrate (e.g. D-glucose or α-D-mannose). The main specific carbohydrate units recognized by lectins are N-acetylneuraminic acid, N-acetylglucosamine, N-acetylgalactosamine, galactose, mannose, and fructose molecules [26]. Most commonly used lectins for antibody purification studies are concanavalin A (Con A), wheat germ agglutinin, mannan-binding protein and jacalin [27]. Con A is a lectin originally extracted from the jack-bean, Canavalia ensiformis and have been intensively preferred as a lectin molecule for affinity chromatography studies due to their affinities towards glycoconjugates containing α-D-mannopyranosyl, α-D-glucopyranosyl and sterically related residues. Because of these unique properties, Con A is the preferred choice for the separation and adsorption of glycoenzymes and carbohydrate bearing biomolecules [24].