Ultrasensitive Detection of Dimethylamine Gas for Early Diagnosis of Parkinson's Disease Using CeO2-Coated Ti3C2Tx MXene/Carbon Nanofibers.

Parkinson's disease is a prevalent neurological disorder, with dimethylamine (DMA) recognized as a crucial breath biomarker, particularly at the parts per billion (ppb) level. Detecting DMA gas at this level, especially at room temperature and high humidity, remains a formidable challenge. This study presents an ultrasensitive chemiresistor DMA gas sensor, leveraging the CeO2-coated Ti3C2Tx MXene/carbon nanofiber (CeO2/MXene/C NFs) heterostructure to enhance dimethylamine sensing. The high conductivity of MXene, combined with C-Ti-O bonds and a sp2 hybridized hexagonal carbon structure, increases surface active sites. The presence of Ce3+ promotes the formation of surface-active oxygen species, while the MXene-CeO2 heterojunction broadens the electron depletion layer. Theoretical calculations reveal that the highest adsorption energy for DMA gas is at the Ce top site, explaining the sensor's satisfactory sensitivity, rapid response and recovery process, low detection limit (5 ppb), and high selectivity at room temperature. The Ce3+/Ce4+ dynamic self-refresh mechanism, involving surface hydroxyl elimination, enhances the sensor's performance under high-humid conditions. Clinical breath tests demonstrate the sensor's ability to distinguish between healthy individuals and Parkinson's disease patients, paving the way for developing next-generation sensors for early diagnosis of neurological disorders.