title: Diffusion in and around alginate and chitosan films with embedded sub-millimeter voids.
abstract: Hydrogel scaffolds from biopolymers have potential use in the controlled release of drugs, and as 3-D structure for the formation of tissue matrix. This article describes the solute release behavior of alginate and chitosan films with embedded voids of sub-millimeter dimensions. Nitrogen gas was bubbled in a fluidic arrangement to generate bubbles, prior to the crosslinking. The crosslinked gel was dried in a vacuum oven, and subsequently, soaked in Vitamin B-12 solution. The dimensions of the voids immediately after the cross-linking of gel, and also after complete drying were obtained using a digital microscope and scanning electron microscope respectively. The porosity of the gel was measured gravimetrically. The release of Vitamin B-12 in PBS buffer on a shaker was studied. The release experiments were repeated at an elevated temperature of 37°C in the presence of lysozyme. The diffusion coefficient within the gel layer and the mass transfer coefficient at the interface with the bulk-liquid were estimated using a mathematical model. For comparison, the experiment was repeated with a film that does not have any embedded void. The enhancement in diffusion coefficient due to the presence of voids is discussed in this article.
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302, India.
authors.forename: Subhajit
authors.initials: S
authors.lastname: Patra
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302, India.
authors.forename: Dharmendra Kumar
authors.initials: DK
authors.lastname: Bal
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302, India. Electronic address: snganguly@che.iitkgp.ernet.in.
authors.forename: Somenath
authors.initials: S
authors.lastname: Ganguly
mesh_terms: D000464:Alginates / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D008567:Membranes, Artificial; D008956:Models, Chemical
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D008567:Membranes, Artificial; D020723:Glucuronic Acid; D048271:Chitosan
keywords: Bubble; Diffusion; Gel; Release; Scaffold