Colorimetric Detection of Chromium Ions in Aqueous Solution Based on Functionalized Gold Nanoparticles with 4-Mercaptobenzoic Acid and Polyethyleneimine

In order to conveniently and rapidly detect Cr 3+ ions in aqueous solution, novel functionalized gold nanoparticles (AuNPs) were designed with 4-mercaptobenzoic acid (4-MBA) and polyethyleneimine (PEI). In addition, we also compared the response signal of various functional AuNPs to Cr 3+ ions on the detection system. The modifiers included 4-MBA, 4-nitrobenzene mercaptan (4-NTP) and PEI, respectively. The results showed that 4-MBA and PEI co-functionalized had better sensitiveness than others. Cr 3+ ions in aqueous solution could be detected by naked eye and UV-Vis absorption spectrum and the limit of detection was 1 μM. The response was found to be proportional to Cr 3+ ions concentration in the range from 2 μM to 10 μM. The developed platform with high selectiveness was successfully utilized to detect Cr 3+ ions in simulated samples.