Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar,Mohali, Punjab-160 062, India, Institute of Biochemistry, Faculty of Medicine, Polytechnic University, Via Ranieri 67, IT-60100 Ancona, Italy,Green Biotechnology Research Group, The Special Division for Human Life Technology, National Institute of Advanced Industrial Science andTechnology, 1-8-31 Midorigaoka, Ikeda, Osaka-563-8577, Japan, and Department of Medicinal Chemistry & Natural Products,The Hebrew University of Jerusalem, School of Pharmacy-Faculty of Medicine, Jerusalem 91120, IsraelReceived March 2, 2004

Chitosan chemistry and pharmaceutical perspectives.

Stimuli-reponsive polymers and their bioconjugates

https://www.farm.ucl.ac.be/FARM2129/2008-2009/Tulkens/anemie-neutropenie/Veronese-Pegylation-Drug-Discovery-Today-2005-10-1451-1458.pdf

PEGylation, successful approach to drug delivery.

Chitosan-based hydrogels for controlled, localized drug delivery

Structure and interactions in covalently and ionically crosslinked chitosan hydrogels for biomedical applications

Enzyme-catalyzed gel formation of gelatin and chitosan: potential for in situ applications

Chitosan based water-resistant adhesive. Analogy to mussel glue.

Hydrogels are increasingly considered for creating three-dimensional structures in miniaturized devices, yet few techniques exist for creating such hydrogel structures. We report a new approach for creating hydrogels using the amine-containing polysaccharide chitosan. Specifically, electrodes are immersed into a slightly acidic chitosan solution and a voltage is applied to promote the proton-consuming hydrogen evolution reaction at the cathode surface. This reaction leads to a high localized pH in the vicinity of the cathode surface, and if this localized pH exceeds about 6.3, then chitosan becomes insoluble and deposits at the cathode surface. As the current density is increased, the region of high pH is expected to extend further from the cathode surface into the bulk solution. Using moderately high current densities (50 A/m2), we observed that chitosan deposited as a thick hydrogel. Measurements of the water content confirmed that the deposited chitosan was a hydrogel. To suggest the potential utility,...

Electrochemically Induced Deposition of a Polysaccharide Hydrogel onto a Patterned Surface

Mechanical properties of biomimetic tissue adhesive based on the microbial transglutaminase-catalyzed crosslinking of gelatin.

The enzyme tyrosinase was used for the in vitro conjugation of the protein gelatin to the polysaccharide chitosan. Tyrosinases are oxidative enzymes that convert accessible tyrosine residues of proteins into reactive o-quinone moieties. Spectrophotometric and dissolved oxygen studies indicate that tyrosinase can oxidize gelatin and we estimate that 1 in 5 gelatin chains undergo reaction. Oxidized tyrosyl residues (i.e., quinone residues) can undergo nonenzymatic reactions with available nucleophiles such as the nucleophilic amino groups of chitosan. Ultraviolet/visible, (1)H-NMR, and ir provided chemical evidence for the conjugation of oxidized gelatin with chitosan. Physical evidence for conjugation was provided by dynamic viscometry, which indicated that tyrosinase catalyzes the sol-to-gel conversion of gelatin/chitosan mixtures. The gels formed from tyrosinase-catalyzed reactions were observed to differ from gels formed by cooling gelatin. In contrast to gelatin gels, tyrosinase-generated gels had different thermal behavior and were broken by the chitosan-hydrolyzing enzyme chitosanase. These results demonstrate that tyrosinase can be exploited for the in vitro formation of protein-polysaccharide conjugates that offer interesting mechanical properties.

Tianhong Chen

Papers

Enzyme-catalyzed gel formation of gelatin and chitosan: potential for in situ applications

Chitosan based water-resistant adhesive. Analogy to mussel glue.

Electrochemically Induced Deposition of a Polysaccharide Hydrogel onto a Patterned Surface

Mechanical properties of biomimetic tissue adhesive based on the microbial transglutaminase-catalyzed crosslinking of gelatin.

In vitro protein–polysaccharide conjugation: Tyrosinase-catalyzed conjugation of gelatin and chitosan