Use of Gold Nanoparticles in a Simple Colorimetric and Ultrasensitive Dynamic Light Scattering Assay: Selective Detection of Arsenic in Groundwater

Abstract

Low level: The amount of arsenic in Bangladeshi well water and in bottled drinking water and Mississippi tap water are indicated by a dynamic light scattering (DLS) assay. Label‐free gold nanoparticles are used in a selective colorimetric assay (see picture) and in a highly sensitive DLS assay for the recognition of arsenic in concentrations as low as 3 ppt.

Gold nanoparticles as efficient sensors in colorimetric detection of toxic metal ions: A review

“…Dynamic light scattering (DLS) analysis was further stated to improve the detection limit to 10 ppt, thereby suggesting DLS to be a more sensitive detection method. The comparatively lower detection limit obtained in case of GNP-DTT was probably due to the binding of As 3+ ions via As-S linkage while in the other two cases (Cys and GSH modified GNPs), As binds via As-O bonds due to the lack of free -SH groups available for binding [49].Similarly, , a two-photon light scattering (TPS) assay was reported to detect As 3+ in waste water samples, where GNPs functionalized using glutathione (GSH) and dithiothreitol (DTT) were exploited. The functionalized GNP probes were also used for detecting S. typhimurium bacterium with an excellent detection limit of 103 bacteria/mL [50].…”

Physical characterization of nanoparticle size and surface modification using particle scattering diffusometry

“…22 Given that DLS is an intensity-based measurement system, this can cause errors in the particle size measurement. [22][23][24] Characterizing the number of protein layers present on a nanoparticle is important for researchers performing layer-by-layer assemblies such as designing tunable vehicles for drug delivery devices. 6,56 Because NHS chemistry was used to covalently bind protein to the bare gold nanoparticle surface, it is expected that only one protein layer should be present on the particle surface.…”

“…Of these techniques, DLS is the most commonly used, 22 measuring particles from the micrometer range down to sub-nanometer sizes. 23 For accurate measurements, this well-established method 24 requires information from the user such as refractive index (RI) and absorption coefficient of the particles along with temperature and viscosity of the fluid medium. 25 This information is not always known a priori and surface modifications may, in fact, change some of these properties.…”

A fluorometric paper-based sensor array for the discrimination of heavy-metal ions

“…As a result, there is an urgent need for lowcost, highly sensitive and selective methods of discrimination of heavy-metal ions, especially at their wastewater discharge standard concentrations (some of them are as low as 10 À 7 M). Instead of trivial analytical instrument methods, a number of inexpensive colorimetric sensors for the detection of heavy-metal ions have been proposed (e.g., modified or functionalized nanoparticles, DNAzyme, nanosized dye based test strips, etc) [10][11][12]. Combining with sensor array technology and pattern recognition method, optical sensor arrays have been extensively applied for the determination of toxic industrial gases [13,14], nucleic acid and biomolecules [15], diols [16], and even for diagnostic [17], etc.…”