Exploring the Potential of a Radioluminescent Light Source for Photobiomodulation

Photobiomodulation (PBM) is a promising technique aiming at slowing down neurodegeneration by illuminating a specific brain region depending on the neurodegenerative disease. Clinatec is currently conducting the world’s first clinical trial with seven patients suffering from Parkinson’s disease (PD), implanted with an intracerebral optical fiber emitting light at 670-nm wavelength. The development of a radioluminescent device employing luminescent materials activated by tritium <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-decay presents significant advantages in this context. This technology can offer multiple benefits: a minimally invasive approach, superior light delivery to tissues due to its compact design and diffuse illumination, and extended energy independence, all contributing to enhanced patient comfort and treatment efficacy. Several strategies for coupling tritium with luminescent materials are documented, including the use of tritium gas, tritiated water, or a solid tritiated matrix. We present here quantitative results on the development of a millimeter-sized radioluminescent device, in which tritium <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-decay excites luminescent materials embedded in a host matrix. The adopted strategy is based on an organic aerogel matrix serving as both tritium and luminescent material reservoir. Cylindrical samples made of cellulose aerogel containing red-emitting Y2O3:Eu+3 phosphors or AgInS2 quantum dots have been fabricated. Samples are placed within an integrating sphere and exposed to a tritium gas atmosphere (from 0.2 to 1.2 bar), allowing us to quantify their optical performance while varying the tritium pressure. Our findings suggest a direct dependence between the radiance and the tritium pressure, as well as a potential mechanism for trapping tritium atoms in luminescent microparticles. On top of that, we could correlate the radiance to the concentration and material composition. This ongoing work holds promise for developing self-powered luminescent devices for optimized PBM in clinical applications.