Seed-mediated in situ growth of photothermal reagent gold nanostars: Mechanism study and preliminary assay application.

Photothermal reagent-mediated portable detection platforms using thermometers as signal readers have received extensive attention due to their simplicity, low cost, and practicality. However, exploitation photothermal reagent with excellent photothermal conversion effect, convenient to synthesize, preferably without any modification for biosensing application, is still challenging. Herein, a simple and rapid seed-mediated in situ synthesis strategy has been developed for the preparation of gold nanostars (AuNSs) with remarkable photothermal conversion effect. By simply changing the seed size and component concentrations involved in the in situ synthesis process, AuNSs have adjustable geometries, allowing the photothermal conversion to be tuned to a high level optimal for biosensing. Meanwhile, an accurate understanding of the photothermal conversion mechanism is obtained by studying the relationship between the morphology of AuNSs and the photothermal effect. Subsequently, using ascorbic acid (AA) as a model target, the preliminary application of AuNSs in constructing a portable photothermal detection platform has been demonstrated. This in situ preparation strategy of AuNSs not only exhibits remarkable photothermal conversion effect, but also avoids complicated and time-consuming synthesis and modification. Therefore, it has great potential to be extended to portable detection of other targets by simply converting the concentration of the target to that of AA.