# Mussel‐Bioinspired Edible Ca2+‐Crosslinked Alginate Hydrogel Electrodes for Glucose Gastrointestinal Monitoring

## TL;DR

Researchers developed an edible hydrogel electrode inspired by mussels for monitoring glucose levels in the gastrointestinal tract.

## Contribution

The novel edible electrode combines ionic and electronic conduction for ingestible glucose monitoring.

## Key findings

- The electrode shows a linear glucose response from 50 µm to 1.0 mm with a detection limit of 10.4 ± 0.8 µm.
- It retains ≥95% activity after 20 hours of operation and 90% after 30 days of storage.
- The hybrid hydrogel enables efficient glucose-to-H2O2 conversion in simulated intestinal fluid.

## Abstract

A novel self‐standing, edible polydopamine‐based alginate‐hydrogel electrode that intrinsically conducts ions and electrons is introduced, redefining the architecture of ingestible bioelectronics. The edible polydopamine‐based alginate‐hydrogel electrode are based on Ca2⁺‐crosslinked alginate (3.5% w/v) plasticized with glycerol (5% w/v) and reinforced with polydopamine, silver nanoparticles, and food‐grade glucose oxidase. The optimized formulation exhibits an electroactive surface area of 1.99 ± 0.07 cm2, a double‐layer capacitance of 10.1 ± 0.3 µF, and a charge‐transfer resistance of 7.7 ± 0.6 kΩ. Structural characterization by SEM, TEM, AFM, WAXS, and FTIR confirms uniform dispersion of AgNPs, pDA domain formation, and stable enzyme incorporation, while rheology and DMA reveal enhanced viscoelasticity, tensile strength (14 MPa), and Young's modulus (65 MPa). Configured as a first‐generation glucose biosensor operating in USP simulated intestinal fluid (pH 6.8), the electrode displays a linear response from 50 µm to 1.0 mm, a detection limit of 10.4 ± 0.8 µm, and an apparent KM
app of 0.35 ± 0.08 mm. The biosensor retains ≥95% activity during 20 h of continuous operation and 90% after 30 days storage, with negligible interference from physiological species. This edible platform establishes a robust route toward ingestible bioelectronics for non‐invasive glucose monitoring and personalized metabolic management.

A fully edible soft electrode is engineered from Ca2⁺‐crosslinked alginate integrated with polydopamine, silver nanoparticles, and food‐grade glucose oxidase. The hybrid hydrogel combines ionic and electronic conduction, enabling efficient glucose‐to‐H2O2 conversion and catalytic reduction in simulated intestinal fluid. This strategy demonstrates a sustainable pathway toward ingestible electrochemical biosensors for real‐time metabolic monitoring.