Development of a fluorometric gamma dosimeter based on a BODIPY-LMG dye-loaded superporous polymer

Abstract

Accurate, easy to use and low-cost gamma (γ) dosimeters are indispensable in gamma irradiation facilities for measuring the absorbed dose. Available γ-dosimeters and detectors have various limitations, which restrict their use in practical applications. Here, we developed a first-of-its-kind solid-supported fluorometric gamma dosimeter. For this, a BODIPY-leucomalachite green dye conjugate (BLMG) was designed and synthesized, which showed colorimetric (yellow to green) and “off–on” fluorescence changes under gamma exposure in chloroform solution. This allowed precise measurement of low dose gamma radiation. Interestingly, the dose range and sensitivity can be changed by optimising the dye concentration, which is beneficial for its application in different gamma irradiation facilities. Detailed mechanistic studies were also performed to confirm the photoinduced electron transfer (PET)-based sensing mechanism. Furthermore, based on this principle, a solid-supported dosimeter was developed. As a solid support, a superporous polyHEMA matrix was used, which was grafted with polyGMA via a high-energy radiation (γ-radiation)-assisted mutual irradiation grafting method to enhance its chloroform-absorbing and -holding capability. Then, the chloroform solution of the BLMG dye was absorbed by this superporous matrix and used for the dosimetric studies, which showed both colorimetric (yellow to green) and ratiometric fluorescence changes upon gamma exposure. The blue fluorescence of the solid matrix changed to bright green fluorescence under gamma irradiation conditions. This fluorescence colour change was quantified, which showed linear changes in the blue and green components of the fluorescence light. This linear response was useful in quantifying the gamma doses (5–45 Gy) accurately. The newly developed solid-supported dosimeter will be highly useful for commercial application in blood irradiation facilities due to its simple detection procedure, low cost and accurate measurement.