Dual-Modal Iridium-Based Self-Immolative Chemosensors for Differential Responses against Reactive Oxygen Species and their Applications to Detect Diabetes

In diabetes, platelets are activated by several stimuli, and the activated platelets generate reactive oxygen species (ROS) to induce the aggregation of platelets followed by thrombus formation resulting in various cardiovascular diseases. Therefore, detecting ROS perturbations in platelets can provide a clue to diagnosing diabetes. In this paper, iridium-based self-immolative probes (1a-1c) are reported to monitor perturbations of ROS in the blood through photoluminescence (PL) and electrochemiluminescence (ECL). The probes are designed based on an iridium complex conjugated with phenylboronic acid pinacol ester through carbamate moiety. Three probes contain distinct electron-withdrawing groups at the ortho-position in the benzyl linker; thus, subtle reactivity differences are expected against ROS. As expected, all three probes exhibit the most apparent PL changes against hydrogen peroxide (H₂O₂), but their response patterns against ROS are interestingly distinctive. Utilizing such differential ROS responsive pattern, a discrimination strategy is established using a combination of PL and ECL responses, and discrimination of platelets from diabetic and control rats is successfully demonstrated.