Synergistic molecular assembly of an aptamer and surfactant on gold nanoparticles for the colorimetric detection of trace levels of As3+ ions in real samples

The use of the synergistic molecular assembly of an aptamer and cetyltrimethylammonium bromide (CTAB) on gold nanoparticles (AuNPs) is described for the selective and sensitive colorimetric recognition of As3+ ions in water samples. The As3+ ions coordinate with Ars-3 aptamer-AuNPs, causing aggregation in the presence of CTAB, which induces a red-shift in the surface plasmon resonance (SPR) band and a visual change in the color. The aptamer has shown a strong tendency to bind with As3+ ions using CTAB as a binder, exhibiting good linearity between the absorption ratio (A(650)/A(520)) and the concentration of As3+ ions (1.0-100 ppb) with a detection limit of 16.9 ppb. In contrast, other chemical species (metal ions and anions) did not induce these changes at all, and thus the aptasensor is highly specific for As3+ ion sensing. The spectroscopic and TEM results show high selectivity for As3+ ion sensing and the assay is completed within 30 min. The aptamer-AuNP-based colorimetric method illustrates the potential utility for screening As3+ ion levels in real samples. The developed aptasensor was successfully applied for the detection of As3+ ions in water and cosmetic samples, signifying its remarkable application for As3+ ion sensing in real samples.