Analyte-mediated growth of gold nanoparticles for non-aggregation-based colorimetric detection of manganese(ii)

Intensive industrial applications of manganese have increased its production from mineral sources, leading to increased emissions into surface and groundwater. The availability of manganese in water sources may result in debilitating health effects. It is, therefore, important to design an analytical method to monitor manganese in water sources. In this study, the localized surface plasmon resonance (LSPR) property of gold nanoparticles (AuNPs) is considered for sensing Mn²⁺. The extinction intensity of AuNPs increases on the addition of Mn²⁺. The extinction intensity of AuNPs increased linearly with the concentration of Mn²⁺ in the range of 0.5-25 µM. The limit of detection (LOD) in the linear range was computed to be 0.269 µM. Mn²⁺, producing the highest extinction response among the tested cations, shows the excellent selectivity of our method towards Mn²⁺. The applicability of the method in real sample analyses was tested using borehole groundwater. The recovery rates from the groundwater analyses ranged from 101-108%, showing the high accuracy of the method in the determination of Mn²⁺. The results show the potential of the method in the determination of Mn²⁺ in various environmental samples. In conclusion, this work shows the potential of the analyte-mediated colorimetric method for the detection of various target analytes.