Rational Molecular Design of Aniline-Based Donor-Acceptor Conducting Polymers Enhancing Ionic Molecular Interaction...

Organic conducting polymers (CPs) are crucial for wearable bioelectronic devices, including biosensors, offering enhanced sensitivity and adaptability for personalized health monitoring. However, the classical CPs molecular structure limits their development of high-performance wearable biosensors. Among all, pH monitoring related to H⁺ ions is important for managing metabolic disorders, monitoring wound healing and various skin diseases. Here, a novel concept is demonstrated for fabrication of high-performance donor-acceptor (D-A) aniline-based CPs with enhanced sensitivity and stability for wearable biosensors. Density functional theory (DFT) calculations are implemented, using aniline as the acceptor and ortho-substituted aniline derivatives as donors. This approach enables precise molecular design of the CPs molecular structure through different conjugated units. Guided by the DFT calculations, donor-donor (D-D) and D-A/CPs, specifically poly(aniline-co-o-fluoroaniline) (P(ANI-co-FANI)) and poly(aniline-co-o-methoxyaniline) (P(ANI-co-MOANI)), are synthesized and examined. The high-performance D-A/P(ANI-co-MOANI) exhibits a significant 1.4- and 3.7-fold increase in sensitivity and 3.6- and 9.0-fold enhancement in stability for pH sensing compared to PANI and D-D/P(ANI-co-FANI). Real-time sweat pH monitoring is further demonstrated with the advanced D-A/P(ANI-co-MOANI)-based wearable pH biosensor during various activities. These findings provide critical insights into designing and synthesizing advanced functional CPs for innovative high-performance organic bioelectronic devices, including sensing, drug delivery, and energy-related applications.