Composite hydrogels with engineered microdomains for optical glucose sensing at low oxygen conditions

Abstract

There is a growing need for advanced tools that enable frequent monitoring of biomarkersfor precision medicine. In this work, we present a composite hydrogel-based system providingreal-time optical bioanalyte monitoring. The responsive material, alginate-in-alginate (AnA),is comprised of an alginate hydrogel with embedded bioactive, nanofilm-coated phosphorescentmicrodomains; palladium tetracarboxyphenylporphyrin serves as an optical indicator, glucoseoxidase as a model enzyme, and layer-by-layer deposited polyelectrolyte multilayers (PEMs) asthe diffusion barrier. Glutaraldehyde crosslinking of the nanofilms resulted in a dramatic reduction inglucose diffusion (179%) while oxygen transport was not significantly affected. The responsesof the AnA hydrogels to step changes of glucose at both ambient and physiological oxygenlevels were evaluated, revealing controlled tuning of sensitivity and dynamic range. Stability,assessed by alternately exposing the responsive AnA hydrogels to extremely high and zero glucoseconcentrations, resulted in no significant difference in the response over 20 cycles. These AnAhydrogels represent an attractive approach to biosensing based on biocompatible materials that maybe used as minimally-invasive, implantable devices capable of optical interrogation. The modelglucose-responsive composite material studied in this work will serve as a template that can betranslated for sensing additional analytes (e.g., lactate, urea, pyruvate, cholesterol) and can be usedfor monitoring other chronic conditions.