In vitro/In vivo oxygen electrochemical nanosensor for bioanalysis

Direct in vivo monitoring of O₂ is critical in the study of numerous biological processes, and the development of novel highly sensitive techniques for O₂ in vivo detection is of great potential importance. Electrochemical amperometric sensors are some of the most promising, easy to operate, inexpensive, sensitive and have a high temporal resolution. As part of this work, we have demonstrated a direct rapid method for molecular oxygen detection inside multicellular spheroids in vitro and rat brain in vivo. External and internal oxygen profiles in human adenocarcinoma MCF-7 spheroids were studied using developed nanoelectrode. The size of spheroids was shown to affect the level of hypoxia inside them, and also affected the oxygen consumption near spheroids in solution. To demonstrate the in vivo relevance of the novel sensor we used it to measure the oxygen concentrations in the superficial layers of the rat brain. This study demonstrates a minimally invasive electrochemical method for real-time oxygen profiling in vivo.