Hemoglobin Inhibition of Superoxide Radical and Holes‐Induced Photobleaching in Zn2GeO4:Mn Long‐Afterglow Nanorods for Tracking of Bloodstains

Abstract The photobleaching of fluorophores is usually seen as harmful in optical sensing and bioimaging as it leads to a loss or permanent drop in their photoluminescence (PL) due to structural damage from prolonged light exposure. Here, this study reveals the fluorescence intensity and long‐afterglow performance of Mn 2+ ‐doped Zn₂GeO₄ nanorods (ZGO:Mn NRs) exhibit significant degradation under irradiation, but their structural integrity remains largely unaffected. This photobleaching phenomenon arises partially from static quenching caused by the adsorption of superoxide radicals (•O 2 − ), which form as photoelectrons transfer to surface‐adsorbed oxygen molecules. Concurrently, the accumulation of residual photogenerated holes promotes non‐radiative relaxation pathways in the excited state of ZGO:Mn NRs, thereby suppressing radiative recombination and diminishing luminescence efficiency. Notably, hemoglobin (HGB) catalyzes scavenging of •O 2 − and photoinduced holes, enabling rapid restoration of fluorescence and long‐persistent luminescence of ZGO:Mn NRs. This specific response offers a simple sensing strategy for detecting HGB, showing a superior sensitivity and anti‐interference ability for visualizing latent bloodstains on various material surfaces. This research will further develop advanced luminescent materials and explore their applications in biosensing, environmental monitoring, and trace evidence analysis.