Bright red fluorescent amphiphilic carbon dots as dualphase and visual sensor for selective detection of As³⁺ in aqueous environment

Increasing attention has been focused in the area of multi-mode sensing method for on-site application to avoid the false positive results and enhance the accuracy label measurements. This article reports the synthesis of bright red fluorescent amphiphilic carbon dots (C-dots) as dualphase fluorescent nanosensor for selective detection of As³⁺ in water. One-pot solvothermal approach was chosen for the C-dots synthesis with a maximum fluorescence quantum yield of 47%. Bright red fluorescence of the C-dots was selectively weakened upon the treatment with As³⁺, although the other competing ions showed infectivity. Static quenching was proved behind this fluorescence attenuation by absorbance and time-resolved fluorescence spectroscopy. The amphiphilicity of synthesized C-dots has been utilized to detect As³⁺ in both liquid and solid phase. Aqueous dispersion of C-dots showed a dramatic fluorescence quenching efficiency of maximum 80%. To fabricate solid phase sensor, C-dots were successfully coated and absorbed on silica beads and cotton buds. These fluorescent solid matrices also displayed a relative good quenching efficiency (70–80%) towards As³⁺ without any leaching out of the C-dots from the solid surface. In addition, these C-dots showed an adequate potentiality to detect this ion in real water sample analysis. These findings would enable a great potentiality in the environmental water contaminants sensing technology.