Real-time measurement of a single living cell energy metabolism using highly photostable and organelle-targeted oxygen nanosensors

The measurement of energy metabolism in a single living cell provides new insights, both in understanding the important biological events, such as differentiation of stem cell, origin of tumor cell and drug resistance, and in studying progression of metabolism related diseases. For decades, scientists have been experimenting with various methods to achieve the goal. But, due to the size and fragility of the cell and the rigorous requirements of experiments, these attempts have not been successful. We have rationally designed a core/shell structured luminescence oxygen nanosensors, in which the chemically incompatible hydrophobic dyes and hydrophilic silica matrix was successfully merged, and resulted in nanosensors with ultra-high photostability, intense brightness, high sensitivity, and excellent biocompatibility. The robustness of silica surface makes it possible for the nanosensors to be featured with active-targeting capability. The nanosensors emitted intense luminescence and had long luminescence lifetime, and both were sensitive to changes of local oxygen concentration. After taken up by living cells, the organelle-targeting nanosensors can precisely sense and quantitatively measure the consumption of oxygen inside a single living cell over long duration, up to 180 min. With the help of mitochondrial inhibitors, the oxygen consumption rate diagram was drawn, which offers detailed clues in studying energy metabolism and health status of a single living cell.