Co₃O₄ needles on Au honeycomb as a non-invasive electrochemical biosensor for glucose in saliva

While glucose monitoring technology is widely available, the continued prevalence of diabetes around the world coupled with its debilitating effects continues to grow. The significant limitations which exist in the current technology, instils the need for materials capable of non-invasive glucose detection. In this study a unique non-enzymatic electrochemical glucose sensor was developed, utilising a gold honeycomb-like framework upon which sharp Co₃O₄ needles are anchored. This composite nanomaterial demonstrates excellent sensing performance in glucose concentrations ranging between 20 μM and 4 mM, exceeding the range required for non-invasive glucose sensing. In conjunction with this high sensitivity (2.014 mA mM^-1·cm^-2), the material possesses excellent selectivity towards glucose for commonly interfering physiological species such as uric acid and ascorbic acid. Glucose detection in synthetic saliva was then performed showing excellent capability in the low concentration range (20 μM-1 mM) for non-invasive sensing performance. Further tests showed good selectivity of the sensor in physiological contaminants commonly found in saliva such as cortisol and dopamine. This development provides excellent scope to create next-generation non-invasive diabetes monitoring platforms, with excellent performance when detecting low glucose concentrations in complex solutions such as saliva.