Scattering analysis of single polyaniline nanoparticles for acidic environmental sensing

Herein, we demonstrate an acidic environmental sensing technique based on polyaniline (PAni) nanoparticles and a nanoscattering spectrum imaging analysis (NSSIA) system. PAni nanoparticles (PNs) were formulated by a homogeneous coating process using Tween® 80 as a surfactant. Subsequently, PNs were immobilized to an aminated glass substrate to sense environmental pH conditions for single PNs, using the NSSIA system. In contrast to dark-field scattering imaging of the PN, the NSSIA system enabled us to obtain scattering spectra for a single PN to specifically identify the environmental pH conditions. Furthermore, the immobilized PN on the substrate exhibited excellent reversibility for the acquisition of the scattering spectra after repeated change of environmental pH.