AptaStrensor (aptamer-based sensor for stress monitoring): The interrelationship between NPY and cortisol towards chronic disease monitoring

Cortisol and NPY are two biomarkers that have been shown to be related with stress, the latter being more associated with neurological stress. The modulation of these biomarkers can be dependent on several factors such as the type and duration of stress one is exposed to. Understanding the role and interplay between these two biomarkers in the modulation of stress would be expedient in the treatment and management of chronic conditions associated with stress. This paper reports the novel use of aptamers for the simultaneous detection of NPY and cortisol in ultra-low volumes (∼2 μL) human sweat, using non- Faradaic Electrochemical Impedance Spectroscopy (nF- EIS). The ions in the sweat rearrange to form an electrical double layer on the electrode surface when the electrode is biased. nF- EIS is able to isolate the modulations in the capacitive region of the electrical double layer as a result of biomarkers binding to their respective aptamers. This paper reports a detection range of 1ng/mL-256 ng/mL for cortisol and 1pg/mL-256 pg/mL for NPY, both covering the physiological ranges for NPY and cortisol respectively in human sweat. In this work, we hypothesize that physical stress would induce an increase in the concentration of cortisol in sweat while expecting to see little to no rise in NPY since NPY has been shown to be modulated in pyschological stress. The developed AptaStrensor platform was demonstrated to detect an upregulation of cortisol in human sweat when subjects were introduced to physical stress (p < 0.05). Concurrently, the developed platform was sensitive enough to detect no significant difference in NPY levels in human sweat when the subjects were subjected to physical stress (p > 0.05). This platform is envisioned to help understand the interplay between cortisol and NPY as a means of monitoring stress-associated chronic conditions.