Resonance light scattering method for the detection of peanut allergen-Ara h 1 using gold nanorods prepared by improved synthesis through the use of a sodium dodecyl benzene sulfonate additive

Peanut allergen is a growing food safety problem because peanut seeds are increasingly used in the food industry. Here we report a resonance light scattering (RLS) method for the detection of peanut allergen-Ara h 1 with gold nanorods (GNRs) prepared by an improved synthesis through the use of an anionic surfactant sodium dodecyl benzene sulfonate (SDBS) additive. The study demonstrated that the use of SDBS allows the reduction of hexadecyltrimethylammonium bromide to 0.05 M as opposed to 0.1 M in well-established protocols, and improves the monodispersity and stability of the GNRs. Moreover, a probe DNA modified with a thiol at its 5' end and a biotin at its 3' end was attached to the surface of the as-synthesized GNRs to form a stem-loop structure by self-assembly through facile gold-thiol affinity. The stem-loop probe was "closed" when the target DNA was absent; however, the hybridization of the target DNA with the probe DNA induces the conformational change to "open", along with the biotin at its 3' end moving away from the GNR surface, which results in an increase of the RLS intensity of the GNRs. The detection limit was found to be 0.06 pM with the linear response ranging from 0.0002 to 50 nM. The present method offers the improvement of rapidity, sensitivity and selectivity compared with other reported methods. It has been successfully applied for the determination of peanut allergen-Ara h 1 in peanut milk beverage.