A colorimetric sensing strategy for detecting 10-hydroxy-2-decenoic acid in royal jelly based on Ag(I)-tetramethylbenzidine

Royal jelly as a functional food has great potential to promote human health. As a unique ingredient in royal jelly, 10-hydroxy-2-decenoic acid (10-HDA) is a vital criterion to evaluate the quality of royal jelly. Current approaches for 10-HDA detection mainly rely on high-performance liquid chromatographic (HPLC), but it requires large-scale equipment and skilled technicians that are costly and time-consuming. Herein, we report a colorimetric sensing strategy for 10-HDA detection based on Ag(I) and tetramethylbenzidine (TMB), a widely used chromogenic reagent. Ag(I) can oxidize TMB to generate oxidized TMB (oxTMB) showing a light-blue color. Due to the chelation with Ag (I), the introduction of 10-HDA can prevent the generation of oxTMB that results in a color fading and a decrease in absorbance. This colorimetric sensing strategy enables highly sensitive detection of 10-HDA with a linear range from 1 μM to 10 μM and a limit of detection of 0.13 μM. More importantly, this 10-HDA assay allows for a visual readout either by a smartphone or the naked eye with low cost, convenience, and rapid response that has been successfully applied for evaluating the quality of royal jelly in actual samples. The sensing strategy developed in this work provides a new colorimetric approach that holds great promise as a point-of-care platform for the food industry.