ArsenazoIII functionalized gold nanoparticles: SPR based optical sensor for determination of uranyl ions (UO22+) in groundwater

Surface plasmon resonance (SPR) based spectrophotometric determination of UO22+ was carried out by arsenazoIII functionalized gold nanoparticles (AZ-AuNPs) based miniaturized detection assay in ground water samples. AZ-AuNPs were synthesized, characterized by transmission electron microscopy (TEM), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR) and dynamic light scattering (DLS) techniques; AZ-AuNPs were of uniform size (∼10nm), dispersed, highly stable and negative charge surface. The addition of analyte (UO22+) into the detection assay led to UO22+-arsenazoIII complex formation and subsequent release of uncapped gold nanoparticules in solution. Agglomeration based SPR response of gold nanoparticles resulted in visual and spectrophotometric change in the detection assay. The UV-vis spectroscopic investigations showed changes in AZ-AuNPs characteristic absorption peak and an additional peak correspond to UO22+-arsenazoIII complex. Ratio of A650nm/A535nm was used to quantify the concentration of UO22+ in environmental samples. The method showed a linear response from 50−300 ppb (R2> 0.95) for UO22+ with the detection limit of 0.081 µM for ground water samples of total dissolve solids concentration of ∼1000 ppm.