Dual stimulus-responsive core-satellite SERS nanoprobes for reactive oxygen species sensing during autophagy

As one kind of reactive oxygen species, hydrogen peroxide (H₂O₂) participated in various cellular biological processes including cell differentiation and inflammation responses. Abnormal H₂O₂ level is closely related to cancer and other diseases. Highly sensitive detection and monitoring H₂O₂ are of great importance for understanding the roles of H₂O₂ in cellular dynamic events. Herein, a novel dual stimulus-responsive core-satellite surface-enhanced Raman scattering (SERS) nanoprobe engineered with manganese dioxide (MnO₂) and silver nanoparticles (Ag NPs) was constructed for sensitive H₂O₂ detection. The sensing strategy is based on the target-triggered degradation both of the "core" and "satellite". In this system, the MnO₂ core not only could be used as solid supporter to generate "hot spots" that can induce strong SERS signals, but also acted as the responsive unit for H₂O₂ sensing together with Ag NPs. A good linear relationship in the range from 1 to 100 μM and limit of detection of 7.44 μM were obtained. Moreover, the nanosensor possessed good repeatability. Based on this strategy, the sensitive detection of cellular H₂O₂ was achieved. Furthermore, the SERS-based H₂O₂ monitoring during the starvation-induced autophagy was realized by the developed nanoprobes. Our study provides a new way for sensitive H₂O₂ detection and opens a new avenue for sensing and detection of other biomolecules.