Intelligent magnetic microrobots with fluorescent internal memory for monitoring intragastric acidity

Abstract

This study investigates the dynamic fluctuations of pH caused by gastric acidsecretion, a process of both biological and clinical significance, withmicrorobots. Abnormal patterns of acidity often indicate gastrointestinaldiseases, underlying the importance of precise intragastric pH monitoring.Traditional methods using fluorescent probes face challenges due to theirfaint solid-state fluorescence, limited target specificity, and accuracy. Toovercome these obstacles, pH-responsive fluorescent organic microparticlesdecorated with magnetite (Fe 3 O4 ) nanoparticles are engineered. Thesemicrorobots exhibit a unique fluorescence switching capability at a critical pH,enabling the monitoring of gastric acidity. The magnetic part of thesemicrorobots ensures magnetic maneuverability to enable targeted navigation.The microrobots’ fluorescence switching mechanism is elucidated throughcomprehensive spectroscopy, microscopy, and X-ray diffraction analyses,revealing molecular-level structural transformations upon interaction withgastric acid and antacids. These transformations, specifically protonation anddeprotonation of the microrobots’ fluorescent components, prompt a distinctfluorescence response correlating with pH shifts. In vitro and ex vivoexperiments, simulating stomach conditions, confirm the microrobots’efficacy in pH-responsive imaging. The results showcase the promisingdiagnostic potential of microrobots for gastrointestinal tract diseases,marking a significant advancement in imaging-based medical diagnostics attargeted locations.