Nur Khaliesah Jamadon, Nurfatini Busairi, Amir Syahir
Abstract
Mercury (II) ion is among the most common pollutants with the ability to affect the environment. The implications from their elevation in the environment are mainly due to the industrialisation and urbanisation processes. Current determination of heavy metal ions primarily depends on sophisticated instruments for heavy metal ions monitoring. A point-of-care detection method was developed using inhibitive enzymatic reaction monitored through a smartphone. Horseradish peroxidase converted 4-aminoantipyrene into a red coloured product visible with the naked eye. A colourless product, on the other hand, was developed to indicate the presence of heavy metals inhibiting the reaction. Naked eye detection showed good selectivity of Hg2+ over other metal ions as a distinctive colour of Hg is observed at 0.5 ppm with the IC50 of 0.290 ppm. This study also investigated and validated the mechanism of Hg2+ inhibition towards HRP using a dynamic light scattering and molecular dynamic simulation. Besides, naked eye detection can be qualitatively determined using the application downloaded via smartphone, namely Colour Assist, suggesting that the naked eye detection does not require expensive instruments to be employed. Thus, naked eye detection was projected to be applied to the environment for its low cost, easy preparation, and rapid technique.
