Hypochlorous Acid-Activated Multifunctional Fluorescence Platform for Depression Therapy and Antidepressant Efficacy Evaluation

Current diagnosis of depression rests on the symptoms, so it still lacks objective criteria. Meanwhile, existing treatment of depression is dominated by antidepressants, which produce troublesome side effects and usually require months to achieve effect. Therefore, more reliable diagnostic criteria and effective therapy are urgently needed. Some core hallmarks in the etiology of depression have been established, including declined neurotransmitters and inflammatory responses, manifesting in oxidative stress. Thus, we fabricated a HClO-triggered multifunctional fluorescence platform (MB-Rs) for simultaneous neurotransmitter/antidepressant delivery and efficacy evaluation. In MB-Rs, although a urea linkage could be specifically cut off by HClO, methylene blue (MB) endowed with excellent anti-inflammatory and optical properties was covalently linked with neurotransmitters (dopamine or 5-hydroxytryptamine) or antidepressants (fluoxetine). Encountering excess HClO in the brain of mice with depression, MB-Rs released corresponding antidepressants and MB with anti-inflammatory and bright fluorescence. By relieving oxidative stress, inflammation, and coinstantaneous increasing neurotransmitters, MB-Rs elicited better antidepressant response and fewer side effects compared with clinical antidepressants. Furthermore, MB-Rs successfully evaluated the efficacy of antidepressants in mice based on HClO-induced fluorescence. Therefore, this work provides a promising platform for depression diagnosis and treatment.