A method of sensing radionuclides in cells is provided that includes exposing a cell of interest to a radiolabeled molecule, encapsulating the cell of interest with a chemical sensor in an encapsulant to hold the cell of interest and the chemical sensor in proximity, where the radiolabeled molecule decays to emit an energetic particle, and detecting a fluorescence or optical absorption signal in the chemical sensor induced by the radio molecule decay, using an illumination source and a detector, where single-cell analysis with the radiolabeled molecule is performed.