Biogenic Microrobotic SERS Sensors for Transcellular ROS Monitoring with Responsive Delivery.

Reactive oxygen species (ROS) play a critical role in tumor progression and therapeutic response, yet real-time monitoring of transmembrane hydrogen peroxide (H2O2) gradients─a key indicator of metabolic activity and antioxidant capacity─remains challenging due to the lack of integrated platforms combining active access and sensitive detection. Here, we present a biogenic microrobotic surface-enhanced Raman scattering (SERS) sensor fabricated from sunflower pollen grains. Leveraging the natural spiky morphology and magnetic actuation, the microrobot achieves controlled membrane penetration to access both intra- and extracellular compartments. The plasmonic surface coating enables high-sensitivity SERS detection with excellent reproducibility, allowing quantitative monitoring of hydrogen peroxide dynamics across the cell membrane. In addition, a responsive polymer coating confers on-demand release capability upon exposure to elevated reactive oxygen species levels. By integrating navigation, transcellular sensing, and triggered release within a single biocompatible platform, this pollen-based microrobot offers a potential strategy for precision monitoring and targeted intervention in the tumor microenvironment.