Tracking and navigation of a microswarm under laser speckle contrast imaging for targeted delivery.

Micro/nanorobotic swarms consisting of numerous tiny building blocks show great potential in biomedical applications because of their collective active delivery ability, enhanced imaging contrast, and environment-adaptive capability. However, in vivo real-time imaging and tracking of micro/nanorobotic swarms remain a challenge, considering the limited imaging size and spatial-temporal resolution of current imaging modalities. Here, we propose a strategy that enables real-time tracking and navigation of a microswarm in stagnant and flowing blood environments by using laser speckle contrast imaging (LSCI), featuring full-field imaging, high temporal-spatial resolution, and noninvasiveness. The change in dynamic convection induced by the microswarm can be quantitatively investigated by analyzing the perfusion unit (PU) distribution, offering an alternative approach to investigate the swarm behavior and its interaction with various blood environments. Both the microswarm and surrounding environment were monitored and imaged by LSCI in real time, and the images were further analyzed for simultaneous swarm tracking and navigation in the complex vascular system. Moreover, our strategy realized real-time tracking and delivery of a microswarm in vivo, showing promising potential for LSCI-guided active delivery of microswarm in the vascular system. Editor's summary: Micro- and nanorobots have been widely proposed for various medical applications, including drug delivery and thrombolysis. However, tracking these swarms of robots in real time has been challenging, especially for imaging modalities that rely on extended exposure to ionizing radiation. Wang et al. report on the use of laser speckle contrast imaging to track a swarm of magnetic nanorobots within blood vessels in real time and guide their endovascular navigation. The authors demonstrated the potential for high contrast imaging and navigation of the swarm of nanorobots in stagnant and flowing blood environments ex vivo and in vivo. The findings offer an opportunity for improvements in targeted endovascular delivery. —Amos Matsiko [ABSTRACT FROM AUTHOR]