(88c) Molecular Engineering of a Colorimetric Nanogel Sensor for Clinical Radiotherapy and Trauma Monitoring

Radiotherapy using ionizing radiation (e.g. X rays) remains a mainstay of treatment modalities for different types of cancers. Overexposure to radiation in the clinic or as part of an adverse event can induce tissue toxicity and damage, whereas underdosing can lead to poor efficacies of tumor ablation. Effective radiation sensors are critical in ensuring optimum delivery to patients undergoing radiotherapy and for patient stratification in cases of radiation exposure. Currently existing sensors possess several disadvantages in rapid radiation detection because of their fragility, sensitivity to light and heat, dose-rate dependence, long processing times, lack of conformation to tissue morphologies and / or high costs. Commonly used Nanodots^TM are expensive, require separate read-out devices and do not conform to tissue morphologies. We developed a novel colorimetric nanogel sensor, based on the formation of maroon-colored gold nanoparticles from their colorless precursor salt formulations, upon exposure to different levels and types of ionizing radiation. By measuring the intensity of color developed with a simple bench-top absorbance spectrophotometer we were able to detect doses typically administered in fractionated cancer radiotherapy (i.e. ranging from 0-5 Gy doses) and beyond. Topographical distribution of delivered radiation doses was qualitatively and quantitatively determined following addition of quenching agents, and the efficacy of the nanogel sensor was demonstrated for different sources of ionizing radiation including protons, electrons, photons and radioactive isotopes. The translational potential of the sensor was demonstrated using anthropomorphic phantoms and in live canine patients undergoing clinical radiotherapy treatments. Our results demonstrate a new generation of nanogel sensors for colorimetric detection of radiation for improving patient safety in clinical radiotherapy and trauma care.