It is very important to control the ionizing radiation dose in radiation therapy, which depends on the accurate and rapid measurement of radiation. Herein, a novel and highly sensitive nanosensor for γ-radiation detection is constructed using single-stranded DNA sequences as radiation-sensitive material and gold nanoparticles (AuNPs) as a signal reporter. Well-dispersed AuNPs gradually aggregated at high salt concentration when the sensor was irradiated, and this change was quantified by the visible spectra and surface plasmon resonance spectra. The radiation nanosensor has excellent linearity in the dose range of 0–100 Gy under optimal conditions. This method is simple and fast, which provides a new path for the γ-radiation dosimeter and has potential applications in the assessment of radiation-induced biological effects.

Fricke gel dosimeters have great potential for three‐dimensional (3D) dose verification in radiation therapy; however, they suffer from time‐dependent ion diffusion after irradiation, severely affecting their stability and reliability. In this work, a pullulan‐based amphiphilic molecule was synthesized, characterized, and self‐assembled into nanogels. Nanogel structures were embedded into gel dosimeters to reduce the diffusion rates, and radiation‐sensitive nanogel‐incorporated Fricke hydrogel nanocomposites were prepared successfully. The results demonstrated that the diffusion coefficient of improved dosimeters was reduced to 0.125 ± 0.001 mm2 h−1, while maintaining the high optical dose sensitivity (0.0410 ± 0.0004 Gy−1 cm−1). It provides a powerful tool toward the practical application of 3D dosimeters.