Detection of mercury ion using surface plasmon resonance spectroscopy based on nanocrystalline cellulose/poly(3,4-ethylenedioxythiophene) thin film.

• A simple and cost-effective technique for mercury ion (Hg2+) detection is proposed. • The technique based on the incorporation of SPR spectroscopy with novel thin film. • The thin film is nanocrystalline cellulose/poly(3,4-ethylenedioxythiophene) (NCC/PEDOT). • This study proved that NCC/PEDOT can enhance the sensitivity of SPR for Hg+. • As low as 2 ppb of Hg2+ can be detected using NCC/PEDOT based SPR spectroscopy. In order to enhance the sensing performance and the sensitivity of surface plasmon resonance (SPR) sensor, a potential sensing layer should be immobilized on a metal thin film. Thus, the immobilization of nanocrystalline cellulose/poly(3,4-ethylenedioxythiophene) (NCC/PEDOT) on gold thin film has been fabricated for mercury ion (Hg2+) detection. Then, the sensing layer thin film has been incorporated with SPR spectroscopy and the SPR reflectivity signal was observed for the interaction between NCC/PEDOT thin film and different concentrations of Hg2+ solution (2–100 ppb). From the obtained SPR signal, important parameters investigated have proven the performance of the sensor. To be highlighted, the sensitivity for NCC/PEDOT-based SPR sensor was 48.5193° ppm−1 for lower concentration of Hg2+. Additionally, the binding affinity constant was calculated by using the Langmuir isotherm model. Therefore, the results displayed the potential sensing of NCC/PEDOT based sensor for mercury ion detection, as the limit of detection was 2 ppb. [ABSTRACT FROM AUTHOR]