Highly sensitive gold nanoparticle-based colorimetric probe for phytate detection with high selectivity over various phosphate derivatives

A competitive-assay-based colorimetric sensing system for phytate was developed using a combination of [Zn3(1,3,5-tris[bis(pyridine-2-ylmethyl)aminomethyl]-2,4,6-triethylbenzene)]6+ as the receptor unit for the phytate and 11-mercaptoundecylphosphoric acid functionalized gold nanoparticles as the reporter unit. The detection limit of this assay system is ∼100 times more sensitive than that reported for colorimetric probes and is compatible with the high sensitivity of previous fluorescent probes. The proposed sensing system can easily detect phytate at less than ∼300 nM with the naked eye. Unlike previous sensing systems, this design provides a high selectivity for phytate over various phosphate derivatives, including ATP, pyrophosphate, and inositol trisphosphate, and works well over a broad pH range.