We questioned if small organic photosensitizers carrying simple functionalities such as hydroxyl and carboxyl groups can oxidatively modify both metal-free Aβ and metal-bound Aβ (metal-Aβ) and alter their aggregation profiles. As shown in Figure , we rationally selected a series of anthraquinone (AQ)-based compounds and tested their capacity to oxidize metal-free Aβ and metal-Aβ upon photoirradiation and, consequently, vary their aggregation. In addition, the detailed mechanism for such reactivity was determined. Moreover, the aggregation behaviors of Aβ species produced upon light activation of the most promising molecule were probed in vivo.