Tunable nanothermometer based on short poly(phenylene ethynylene)

We report a self-referencing ratiometric nanothermometer based on short conjugated polyelectrolytes (CPEs). The probe is prepared by complexing a phenylene-based polymer with polyvinylpyrrolidone (PVP), an amphiphilic macromolecule that destabilizes CPE pi-pi stacking. This makes it possible to shift the equilibrium between the less emissive aggregated state of the CPE (520 nm) and its more emissive single chains (450 nm) within a useful temperature range (15.0-70.0 degrees C). By testing different PVP molecular weights, we managed to tune the probe thermal sensitivity and response time. Given its potential wide applications, the probe was tested under different pHs and using divalent and monovalent cations. We believe the reported nanothermometer will prove instrumental for ongoing efforts to accurately map and investigate heat production and dissipation at the nanoscale level.