Communicating Particles: Identification Taggant and Temperature Recorder in One Single Supraparticle

""Communicating particles"" are reported that combine an identification (ID) taggant and a temperature recorder in one single entity-a micron-scaled supraparticle. The optical information carriers within the hybrid inorganic-organic supraparticles are three different types of luminescent nanoparticles, which can be read-out using single-wavelength excitation. These three nanoparticle types are assembled into a core-satellite structure via a two-step droplet evaporation technique. The core is built-up from Tb3+ and Eu3+-doped nanophosphors, providing an environmentally stable ID that is easily tunable through ratiometric spectral coding. This core is surrounded by organic, dye-doped polymer nanoparticle satellites, acting as thermal-history-recorders of their environment. Exposed to a threshold temperature, the luminescence of the utilized 7-diethylamino-4-methylcoumarin-doped polymer nanoparticles is irreversibly quenched. This ""turn-off"" signal response is attributed to conformational changes in the dyes' excited state and an alteration of their molecular environment, respectively, triggered by the polymer nanoparticles' glass transition. Thus, the sensitivity of the temperature recorder can be configured over a wide temperature range by varying the dye-hosting polymer. At the same time, the ID of the particle, stemming from its inorganic building blocks, stays unaffected, thus stable against thermal changes. The idea of communicating particles introduces a promising concept for smart additives.