A novel colorimetric method based on silver nanoprisms for determination of 6-TG

In this study, we introduced a new method for the colorimetric detection of a chemotherapeutic drug, 6–thioguanine (6-TG), based on interaction between silver nanoprisms (AgNPrs) and halide ions. AgNPrs have a strong localized surface Plasmon resonances (LSPR) extinction band which can be tunable throughout the visible and near infrared (NIR) regions by controlling their edge length, thickness, and morphology [1]. In this work, AgNPrs were synthesized in mild condition at room temperature and characterized by UV-vis absorption spectroscopy and transmission electron microscopy[2]. It was found that in the presence of halide ions, such as Br- and I-, the color of as-prepared AgNPrs changed from blue to red. Indeed, halide ions could attack the corners of AgNPrs and etch them, which leads to the morphological transformation from nanoprisms to nanodisks[3]. We also observed that the addition of 6-TG to the mixture AgNPrs/ halide ions led to the solution color remain blue. It can be attributed to the protection effect of 6-TG on the corners of AgNPrs. Based on this phenomenon, a novel colorimetric method was developed for the determination of 6–TG in the concentration range of 1-750 ppb, with a detection limit of 0.4 ppb. The developed method was applied to the determination of 6–TG in biological samples with satisfactory results.