Colorimetric detection of Al3+ ions using triazole–ether functionalized gold nanoparticles

A sensitive, selective colorimetric Al3+ detection method has been developed by using triazole–ether functionalized gold nanoparticles (TTP–AuNPs). Gold nanoparticles were prepared by reducing HAuCl4 with sodium borohydride in the presence of 5-(1,2-dithiolan-3-yl)-N-(prop-2-yn-1-yl)pentanamide (TP). The azide part of 2-[2-(2-azidoethoxy)ethoxy]ethanol and the acetylene part of TP were combined to form a triazole structure through a click reaction. Aggregation of TTP–AuNPs was induced immediately in the presence of Al3+ ions, yielding a color change from red to blue. This Al3+-induced aggregation of TTP–AuNPs was monitored first with the naked eye and then UV–vis spectroscopy with a detection limit of 18.0 nM. The TTP–AuNPs showed excellent selectivity for Al3+, compared to other metal ions (Ag+, Ca2+, Cd2+, Co2+, Cu2+, Cr3+, Fe2+, Fe3+, Hg2+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+). In addition, TTP–AuNPs were used to detect Al3+ in sea water samples, with low interference.