Non-enzymatic glucose detection using free-standing gold nanoparticle loaded carrageenan hydrogel electrodes

The current manuscript reports the development of free-standing nanomaterial-modified hydrogels that can be explored for sensing applications. Most of the nanomaterial-hydrogel systems developed till now rely on the modification of an electrode as the supporting substrate on which the electrochemical reactions can occur. These substrates can be pencil electrodes and or screen-printed electrodes. This widely limits the use of hydrogels which can be used as scaffolds and can be explored for the fabrication of free-standing electrodes. Since the functionality of only carrageenan hydrogel is quite limited the current manuscript reports the loading of gold nanoparticles inside the hydrogel matrix which makes it functionally active. The successful synthesis of the modified hydrogel was confirmed with SEM and elemental analysis. The rheological data confirmed the positive effect of gold loading on the carrageenan gel storage modulus. As a proof of concept, the work reports the non-enzymatic electrochemical detection of glucose using gold nanoparticle loaded carrageenan hydrogel. The sensor showed a linear response towards varying glucose concentrations (0 to 2.5 mM). The hydrogel systems can be incorporated into wearables and implantable sensors and can be extended for the detection of other biomarkers in bodily fluids.