Stabilization of the ring-opened Rhodamine probe via multinoncovalent interactions for dual-mode detection of nitazenes

Abstract

Nitazene opioids, representing a potent class of emerging synthetic substances, have emerged as a significant threat to public health and biosafety worldwide. However, due to their chemical inertness and structural diversity, the conventional sensing mechanisms are still challengeable for the sensitive and on-site detection. Herein, we report Rhodamine B hydrazide (RhB-I), a probe which could be engineered to stabilize in its ring-opened form through multi-noncovalent interactions with nitazenes, enabling sensitive colorimetric-fluorescent dual-mode detection. The RhB-I probe exhibited superior detection performance, including a desirable limit of detection (LOD, 2.5 μg/mL), a rapid response (4 s), robust anti-interference capability against 22 potential interfering substances, and successful extension to detect eight additional nitazene derivatives. Notably, the RhB-I-based sensing platform enables accurate nitazene detection in biological matrices including saliva, hair, blood and urine, with saliva and urine requiring no pretreatment, as well as in e-cigarette oil and authentic specimen (tobacco). This work overturns the traditional paradigm that Rhodamine probes rely on analyte chemical reactivity, providing a novel strategy for detecting chemically inert small molecules and expanding the application scope of Rhodaminebased sensing.