Putz, S. / Kassar, M: / Oelschlaeger, C. / Franzreb, M. / Kabay, G. (2024)

Adv. Funct. Mater., 2024, 2316469, doi.org/10.1002/adfm.202316469

Abstract

Despite the critical role of hydrogels in material science and biotechnology, current methods for analyzing their formation lack real-time monitoring and require complex sample preparation and instrumentation. In this work, an innovative methodology is introduced for the real-time analysis of enzymatically catalyzed hydrogelation. Electrochemical impedance spectroscopy (EIS) coupled with interdigitated electrodes (IDEs) to sense and transduce the gelation reaction of model precursor carboxymethyl cellulose-tyramine (CMC-TA) conjugates that undergoes enzymatic cross-linking by horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). Real-time monitoring involves single-frequency analyses at 3 × 105 Hz, where the measured impedance consists solely of a resistive component, and the admittance equates to solution conductance. The gelation trajectories for all tested enzymatically cross-linked hydrogel component combinations are determined by substituting the conductance data in the modified Michaelis–Menten kinetic model. Specifically, for CMC-TA cross-linked by HRP, the authors calculate apparent KM and kcat values of 82.1 µM and 95.5 s−1, respectively. These findings are further validated through rheological characterization, including oscillatory shear measurements and microrheology. Overall, this research paves the way for a streamlined, accurate, and cost-effective approach to controllable enzymatically initiated hydrogel synthesis, enhancing their successful application in various fields ranging from material science to biotechnology.

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