<p>We experimentally investigate how electronic interactions between dopamine molecules and TiO₂ influence the photoluminescence (PL) quenching behavior of TiO₂ nanorods with different crystalline phase structures. Both single-phase rutile TiO₂ nanorods (R-TNRs) and mixed-phase anatase/rutile TiO₂ nanorods (A/R-TNRs) show pronounced dopamine concentration-dependent PL quenching; however, a clear phase-dependent effect is observed, with A/R-TNRs demonstrating a significantly higher PL quenching efficiency than R-TNRs. Specifically, at a dopamine concentration of 0.001&#xa0;µM, the PL quenching efficiency of A/R-TNRs reaches approximately 46%, whereas the corresponding values for R-TNRs are only 21%. The dopamine-concentration-dependent PL quenching of TiO₂ nanorods is primarily attributed to dopamine oxidation induced by photogenerated charge carriers and/or interfacial charge transfer from TiO₂ nanorods to dopamine quinone. In contrast, the markedly enhanced PL quenching efficiency observed for A/R-TNRs arises from the combined effects of their higher surface reactivity, associated with both the mixed-phase nanorods and the anatase phase TiO₂ thin film substrates, and the improved exciton dissociation efficiency induced by the coexistence of anatase and rutile phases. These results not only provide a comprehensive understanding of the interaction between dopamine and TiO₂ that governs the PL quenching behavior of TiO₂ nanorods but also highlight the strong potential of anatase/rutile TiO₂ nanorod-based architectures for high-sensitivity dopamine sensing applications.</p>