Multifunctional Microflowers for Precise Optoacoustic Localization and Intravascular Magnetic Actuation In Vivo

Efficient drug delivery remains a significant challenge in modern medicine and pharmaceutical research. Micrometer-scale robots have recently emerged as a promising solution to enhance the precision of drug administration through remotely controlled navigation within microvascular networks. Real-time tracking is crucial for accurate guidance and confirmation of target arrival. However, deep-tissue monitoring of microscopic structures in vivo is limited by the sensitivity and spatiotemporal resolution of current bioimaging techniques. In this study, biocompatible microrobots are synthesized by incorporating indocyanine green and iron oxide nanoparticles onto copper phosphate microflowers using a layer-by-layer approach, enhancing optoacoustic contrast and enabling magnetic navigation. Magnetic control of these particles under optoacoustic guidance is demonstrated in vivo. Furthermore, super-resolution optoacoustic imaging, achieved through individual particle tracking, is shown to enable the characterization of microvascular structures and quantification of blood flow. The combination of the microflowers' high carrying capacity, in vivo actuation, and high-resolution tracking capabilities opens new opportunities for precise microvascular targeting and localized administration of theranostic agents via intravascular routes.