Kinetic controlled synthesis of pH-responsive network alginate.

Alginates are of considerable interest in the fields of biotechnology and biomedical engineering. To enable the control of properties generally not possible with the native polymer, we have chemically modified alginate with dialdehyde via acid-catalyzed acetalization. The kinetics of acetalization measured through equilibrium swelling of the networked polymer were found to undergo a zero- and second-order reaction with respect to alginate and dialdehyde, respectively. With the determined rate constant of 19.06 microL x mole(-1) x s(-1) at 40 degrees C and activation energy of 78.58 kJ x mol(-1), a proposed predictive reaction model may be used a priori to select reaction conditions providing specific polymer properties. Gel swelling and average pore size were then able to be controlled between 80-1000-fold and 35-840 nm, respectively, by predictive estimation of reagent concentration and formulation conditions. This semisynthetic but natural polymer is stimuli-responsive exhibiting high water absorbency and may potentially be used as drug delivery vehicle for protein therapeutics.