Rapid detection of inorganic arsenic: A real-time screening method based on de-aggregation of gold nanoparticles

The proposed research is designed as a response to the important challenge of monitoring inorganic arsenic (iAs³⁺) in the environment. Arsenic is one of the most serious pollution problems of our time. Long-term exposure causes serious physiological implications i.e., heart disease, stillbirth and cancer, requiring frequent determination in water, soil, agricultural and food samples. Traditional methods of detection, together with the advanced rapid techniques, possess major on-site limitation revealing their inadequacy for real-time analysis. Thus, an early and rapid detection of iAs³⁺ followed by corrective and/or prevention actions can lead to reduction of the polluting impact to safeguard public health. The main goal of this project is to develop a generic integrated biosensing platform for the detection and quantification of iAs³⁺ pollutants in aqueous solutions at low-level concentrations. Gold nanoparticles (GNPs) play a key role in the development of smart sensors and detection agents. Their high surface to volume ratio and unique optical properties facilitate the development of highly sensitive analytical tools for biosensing applications accompanied with the advantages of on-site applicability. Addition of real water to the GNPs induce aggregation, attributed to the water’s high salinity content by screening the negative charges that stabilize them. Herein, our sensing approach is based on nanoparticles de-aggregation estimation in the presence of iAs³⁺ residues, by monitoring the chemiluminescence signal. The resulting assay allows for specific detection of iAs³⁺ while presenting detection limit of 0.1 ppb obtained within two minutes. Overall, the main advantage of the presented biosensing concept is the ability to detect inorganic arsenic ions with high sensitivity, using a simple and portable experimental setup. The specific biosensor design can be chemically/biologically functionalized and adapted for selective sensing of other heavy metals by varying the stabilizing agent of the functional modification at the early stage of GNPs design and synthesis.