Polyester-tethered near-infrared fluorophores confined in colloidal nanoparticles:Tunable and thermoresponsive aggregation and biomedical applications

Intricate assembly of multiple molecular chromophores assisted by protein scaffolds is essential in tuning the optical absorption and energy transfer in the light-harvesting complexes of the photosynthetic systems in nature.However,it remains a challenge to achieve such structural complexity and functionality in synthetic polymer-chromophore systems.Here,we report a series of polyester-tethered pyrrolopyrrole cyanine derivatives and their colloidal nanoparticles dispersed in water,which show tunable J-or H-aggregation excitonic coupling and near-infrared fluorescence by precise control of the polymer chain lengths,composition,and temperature.Moreover,the optimal fluorescence or photothermal effect of the Jaggregate nanoparticles enables broad applications in fluorescence or photoacoustic bioimaging and phototherapy.