Dynamic, 3D Schiff base networks for medical applications. Issue 43 (12th August 2020) - Modak, Piyush
Abstract: In this study, we utilized the reversible property of aqueous Schiff bases to design a dynamic three‐dimensional (3D) network. Two derivatized polysaccharides—acrylated chitosan (aCHN) and oxidized dextran (oDEX)—form a 3D network rapidly (<10 s) in situ without the use of external crosslinking agents. Reversible Schiff base (NC) pairs are formed between the amines of aCHN and aldehydes of oDEX. These bonds are mobile and reversible, allowing the network to form additional bonds, leading to lower energy state and densification. In the presence of a primary organic amine, the network dissolves completely, demonstrating network reversibility. The network has strong cohesion (85 ± 7 mmHg) and adhesion (0.017 ± 0.003 MPa) strengths. Rheological examination of the network demonstrates that both elastic storage (G') and viscous loss (G") moduli do not plateau but keep increasing over time. The network shrinks continuously over time, expelling fluid even when completely immersed in physiological solution, in contrast with conventional crosslinked networks that imbibe water and swell. Both rheology and shrinkage demonstrate the dynamic nature of the aCHN–oDEX networks. The dynamic nature of these networks is tunable and the properties of gelation, rheology, cohesion, adhesion, and densification can be modulated depending on the application of interest. Abstract :