Colorimetric As (V) detection based on S-layer functionalized gold nanoparticles

Herein, we present simple and rapid colorimetric and UV/VIS spectroscopic methods for detecting anionic arsenic (V) complexes in aqueous media. The methods exploit the aggregation of S-layer-functionalized spherical gold nanoparticles of sizes between 20 and 50nm in the presence of arsenic species. The gold nanoparticles were functionalized with oligomers of the S-layer protein of Lysinibacillus sphaericus JG-A12. The aggregation of the nanoparticles results in a color change from burgundy-red for widely dispersed nanoparticles to blue for aggregated nanoparticles. A detailed signal analysis was achieved by measuring the shift of the particle plasmon resonance signal with UV/VIS spectroscopy. To further improve signal sensitivity, the influence of larger nanoparticles was tested. In the case of 50nm gold nanoparticles, a concentration of the anionic arsenic (V) complex lower than 24ppb was detectable. S-layer-functionalized spherical gold nanoparticles are used for detection of arsenic species by colorimetric method. The aggregation of the nanoparticles results into color change from wine red for widely dispersed to blue for aggregated nanoparticles. Additionally, UV/VIS spectroscopy allows an increase of the detection sensitivity up to 24ppb. [Display omitted] •A general method for AuNP functionalization with S-layer proteins is proposed.•A colorimetric assay based on AuNP, covered with S-layer protein is presented.•The high specific binding affinity of JG-A12 S-layer proteins to arsenic (V) is proven.•Detection limits of 24ppb for arsenic (V) is reached using UV/vis spectroscopy.