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

Abstract

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 μM. The detection limit (3σ) of this method was 43 μM. The proposed approach was successfully used for the determination of analyte in human plasma sample.