Effects of hydrophobic modification of chitosan and Nafion on transport properties, ion-exchange capacities, and enzyme immobilization

Controlled Deposition of Structured Polymer Films: Chemical and Rheological Factors in Chitosan Film Formation

“…[1][2][3] Because of chitosan's demonstrated ability to immobilize enzymes in scaffold electrodes 1,2,4 and to provide enzyme stabilizing chemical microenvironments, 1,2,[4][5][6][7][8][9] new information regarding the utility of the spread-coating technique to fabricate micron thin chitosan biopolymer films, in terms of its ability to control film thickness and morphology, could prove of great benefit with regards to the field of enzyme immobilization and the production of chitosan-based biofuel cell electrodes and biosensors.…”

“…10,11 Although Nafion is capable of immobilizing a variety of enzymes, it is expensive and is lacks biocompatibility and biodegradability. 5 Chitosan is, therefore, an ideal alternative to Nafion as it is less expensive, biodegradable and has better biocompatibility.…”

“…For example, deacetylated chitosan can be chemically modified to introduce amphiphilic micellar structure. [5][6][7][8][9]15,16 Introduction of an N-alkyl moiety on the water/acid soluble, hydrophilic polymer backbone yields a hydrophobic side chain, making the polymer amphiphilic, a characteristic that allows micellar structure or soluble aggregates to form. Evidence for the formation of micellar regions in chitosan have been detected via transmission electron microscopy, fluorescence spectroscopy, and static and dynamic light scattering experiments.…”

“…[5][6][7][8][9] Although the formation of micelles depends on entropy, the structure of the micellar regions of chitosan solutions depends on the relative amounts of intra-and intermolecular chemical/electronic interactions as well as key process variables, such as polymer concentration. 3,5,6,15,16 These chemical interactions include hydrogen bonding which occurs between the hydroxyl functional groups of the polymer backbone within a particular polymer strand, between neighboring strands, and with water molecules in the solution. Hydrogen bonding and electrostatic repulsions of the polyelectrolytic backbone, along with van der Waals dispersion forces that are present between all molecules, provides the attractive and repulsive interactions that are responsible for the differences in amounts of intra-and intermolecular aggregation of the hydrophobic side chains along the chitosan backbone.…”

“…3,5,6,15,16 Klotzbach et al, 2006 suggested that the optimal length of the hydrophobic side chain should contain between 4 and 10 carbons, proposing that if the length of the side chain becomes too large, the number of micellar domains will decrease but the size of the domains will increase. 5 By contrast, if the length of the side chain is too small or nonexistent, micellar structure within the polymer strands will not form.…”