As illustrated in Figure , Aβ42 was freshly prepared in 20 mM HEPES, pH 7.4, 150 mM NaCl (1% v/v DMSO; vehicle), exposed to light for 1 h with and without Alo, incubated for an additional 2 h, and directly injected into the hippocampus of murine brains. The hippocampal region is vital for memory formation and retrieval in both murine and human brains and is highly affected by Aβ aggregates formed during the progression of AD. After 15 days of injection, the brain sections were obtained and stained with antibodies or fluorescence dyes to determine the deposition of Aβ oligomers or fibrils in the hippocampus. As displayed in Figure , both compound-free and Alo-added Aβ42 species were safely injected into the hippocampal region, as confirmed by immunostaining with an anti-Aβ primary antibody (6E10). Interestingly, only the brain samples, which were administered with compound-free Aβ42 species and incubated for a long time in vivo, showed the formation of Aβ42 aggregates such as oligomers [detected by immunostaining with an anti-oligomer primary antibody (A11) ] or fibrils {visualized with fluorescent dyes [thioflavin-S (ThS) for Aβ fibrils or DAPI for Aβ fibrils and cellular nuclei ]}.