In vivo 3D Printed Anorectal Probe for Early Detection of Age-related Bowel Dysfunction

An age-related decline in bowel function leads to chronic constipation and faecal incontinence, affecting approximately 7 million older adults. These conditions can significantly reduce quality of life and contribute to social isolation. Although the causes of age-related dysmotility are likely multifactorial, numerous studies suggest that localized changes in the bowel epithelium profoundly impact anorectal function. Within the mucosal region reside enterochromaffin (EC) cells, which play a critical role in bowel function due to their activity as luminal transducers.
Our research, along with others, has demonstrated that serotonin (5-HT) released from mucosal EC cells can modulate bowel function and influence contractility. Consequently, our project focused on developing an in vivo electrochemical sensor to detect 5-HT levels in the anorectum across aging.
We fabricated the probe using a dual-extruder 3D printer, employing carbon/polylactic acid (PLA) to create the electrodes, which were encased in PLA housing. A quasi-reference electrode was formed by coating one of the electrodes with silver paint. The probe was lubricated with a hydrogel and tested using 5-HT. Differential pulse voltammetry was employed to evaluate the probe’s linear range and stability for 5-HT detection.
The probe was then used to monitor in vivo 5-HT levels in the anorectum of mice aged 12 to 18 months. It demonstrated sufficient sensitivity to detect physiological levels of 5-HT and revealed age-related changes in 5-HT concentration within the anorectum. These findings offer valuable insights into age-associated alterations in 5-HT and may contribute to the early identification of bowel dysfunction in older populations.