A multichannel Au nanosensor for visual and pattern inspection of fatty acids

Fatty acids (FAs) are important dietary sources of fuel for animals and structural components for cells. The number, position and configuration of olefins in the alkyl chains play important roles in the impacts of FAs on human health. Currently, structural profiling of FAs in edible oils and fats is an important issue in nutrition industries and food safety. Due to the lack of distinct functional groups, it is extremely difficult to discriminate FAs with structural differences by facile and in situ sensing methods. A few chemosensors have been developed for shape selective sensing of FAs, but their capability and performance were still limited. Herein, for the first time, we proposed a multichannel Au nanosensor for visual and pattern-generating inspection of FAs based on the highly selective binding ability of Ag⁺ to olefinic bonds and Ag⁺ regulable color variation of Au nanoparticles. As a result, the nanosensor showed good selectivity for five FAs with subtle structural difference as low as 5 nM. By further deriving three channel signals in respect of color and color depth, a signature-like signal pattern could be generated by principal component analysis for each FA and even different FA mixtures such as edible oils. Hence, structural variation of FAs in edible hot pot oils with heat treatment was successfully monitored by this Au nanosensor over time. This sensor holds great promise in point-of-care inspection of edible oils and fats.