A Visual Colorimetric Probe for Naked-Eye Detection of Pamidronate Disodium in Human Plasma Based on Aggregation of Citrate-Capped Gold Nanoparticles

Herein, a sensitive, simple, and rapid colorimetric assay for the detection of pamidronate disodium was developed based on the aggregation of citrate-capped gold nanoparticles (AuNPs). This was exploited from the affinity of electron-rich atoms toward the surface of AuNPs, resulting in the aggregation of AuNPs through intermolecular hydrogen bonding interactions. As a result of aggregation under optimum conditions ([NaCl] = 25 mM, [AuNPs] = 3.3 nM and pH 7.0), the color of AuNPs was changed from red to blue and the plasmon band of AuNPs around 520 was decreased along with the formation of a new peak at a longer wavelength in the approximate range of 600 to 700 nm. The intensity ratios of absorbance at 650 nm to the original wavelength of 520 nm display a linear relation to the pamidronate disodium concentrations in the range of 50-225 mu M. The detection limit (3 sigma) of this method was 43 mu M. The proposed approach was successfully used for the determination of analyte in human plasma sample.