Polymerisation and characterisation of conducting polyaniline nanoparticle dispersions

Micellar emulsion chemical polymerisation of polyaniline (PANI) using dodecylbenzenesulfonic acid (DBSA) as the micelle and dopant was performed at 20 °C. It was necessary to use a ratio of 1:1:1 for aniline, oxidant (ammonium persulfate APS) and DBSA to produce the PANI · DBSA in the emeraldine salt (ES) form in large quantities (40 g). The resulting polymer was a nanodispersion with spherical particles 10 ± 2 nm in diameter and an electrical conductivity of 15 ± 3 S cm−1 as determined by transmission electron microscopy (TEM) and the four-point probe method, respectively. UV–vis spectral characterisation showed the nanodispersion to be highly doped. Complete deprotonation of the polymer to the emeraldine base form using 0.5 M NaOH was only possible upon dilution to approximately 0.05% w/v polymer. Reduction of the polymer to leucoemeraldine using phenylhydrazine was relatively slow; however, oxidation to pernigraniline in 0.25 M APS occurred instantaneously

Point of care monitoring of hemodialysis patients with a breath ammonia measurement device based on printed polyaniline nanoparticle sensors

A device for measuring human breath ammonia was developed based on a single use, disposable, inkjet printed ammonia sensor fabricated using polyaniline nanoparticles. The device was optimized for sampling ammonia in human breath samples by addressing issues such as variations in breath sample volume, flow rate, sources of oral ammonia, temperature and humidity. The resulting system was capable of measuring ammonia in breath from 40 to 2993 ppbv (r2= 0.99, n = 3) as correlated with photoacoustic laser spectroscopy and correlation in normal human breath samples yielded a slope of 0.93 and a Pearson correlation coefficient of 0.9705 (p < 0.05, n = 11). Measurement of ammonia in the breath of patients with end-stage kidney disease demonstrated its significant reduction following dialysis, while also correlating well with blood urea nitrogen (BUN) (r = 0.61, p < 0.01, n = 96). Excellent intraindividual correlations were demonstrated between breath ammonia and BUN (0.86 to 0.96), which demonstrates the possibility of using low cost point of care breath ammonia systems as a noninvasive means of monitoring kidney dysfunction and treatment. © 2013 American Chemical Society