A novel molecularly imprinted composite–based electrochemical sensor constructed from o-phenylenediamine and gold nanoparticle–embedded multiwalled carbon nanotube for ultra trace level detection of triclosan

Tuning the parameters related to the sensing mechanism, a novel sensing electrode was fabricated to construct a sensor for triclosan detection at ultra-low level. A novel molecularly imprinted composite (Au@MIC) was synthesized from o-phenylenediamine (o–PD), gold nanoparticle (Au-NP)–embedded -COOH-functionalized multiwalled carbon nanotube (Au-cf-MWCNT), and triclosan as template by cyclic voltammetry (CV) on Au-cf-MWCNT–coated glassy carbon (GC) electrode (Au-cf-MWCNT/GC), following removal of surface triclosan. This novel electrode (Au@MIC/Au-cf-MWCNT/GC) provided a limit of detection (LOD) of 50 ppt of triclosan, which was lower than the LOD achieved by using MIC/cf-MWCNT/GC, mentioned in our earlier work. The sensor showed a good linearity in the range from 75 ppt to 5 ppb on a logarithmic scale. Langmuir adsorption isotherm gave the best fit for Au@MIC/Au-cf-MWCNT/GC with -ΔG_ads value of 65.925 kJ/mol indicating stronger chemisorption. The -ΔG_ads value was higher than that achieved for MIC/cf-MWCNT/GC. To understand the role of Au-cf-MWCNT in detection of triclosan, CV, electrochemical impedance spectroscopy, and electrochemical band gap studies were conducted. This electrode was able to withstand several ions of similar structure of triclosan showing good selectivity.