The featured article on the cover of Small, titled "Ratiometric Nanothermometer Based on a Radical Excimer for In Vivo Sensing" and led by Jaume Veciana and Imma Ratera from the Nanomol-Bio Group (ICMAB, CIBER-BBN) and their team, investigates organic nanoparticles based on persistent TTM radicals. In vivo experiments demonstrate that these nanoparticles function as ratiometric nanothermometers, showing significant promise in the field of biological thermometry.