The best strategy of fighting “free radical diseases” (as cancer, neurodegeneration, atherosclerosis, etc.) is an effective early stage diagnosis. This study proposes a new concept to realize revolutionary class contrast agents to be applied as sensitive probes for detection of “oxidative stress” during development and progression of different pathologies, by using optical and magnetic resonance imaging techniques.We developed a new “oxidative stress” sensor (OxiStressSens) based on conjugation of quantum dots with multi-nitroxide-functionalized cyclodextrin. The oxidation of nitroxide residues to their radical form was accompanied by strong quenching of quantum dot fluorescence and appearance of high EPR contrast. In opposite, the reduction of nitroxide residues in their hydroxylamine form was accompanied by rapid decay of EPR signal and appearance of strong fluorescence signal. Thus, OxyStressSens allows evaluation of the balance between reducers/oxidizers and level of “oxidative stress”. Besides the large magnetic moment or high quantum yield, the dimension of OxiStressSens and its positive charge ensure enhance permeability and retention effect in cells and tissues. The sensor enters into viable cells, which was visualized by EPR and fluorescent imaging. OxyStressSens was applied for detection of “oxidative stress” in cell suspensions, treated by rotenone and 2-methoxyestradiol – a combination, inducing mitochondrial dysfunction, overproduction of superoxide and mild or severe oxidative damages. The physicochemical characteristics and easy cell permeability give a reason to believe that the sensor will be appropriate for in vivo imaging. Since the T1-weigheted MRI contrast of nitroxides follows the same dynamics as their EPR contrast, the sensor is applicable also for nitroxide-enhanced MRI studies.Acknowledgements: This study was supported by the Japanese Society for Promotion of Science (JSPS), Grant-in-aid “Kakenhi C”.ISER-450th International Conference on Nanoscience, Nanotechnology & Advanced Materials (IC2NAM-2018
