Oligodots: Structurally defined fluorescent nanoprobes for multi-scale dual-color imaging in vitro and in vivo.

Nanoscale fluorescent probes are of great importance due to their capabilities for imaging on multiscale. Herein, we report the first synthesis of structurally well-defined nanoparticulate 'oligodots' developed for multi-color imaging in vitro and in vivo. These nanoparticles are prepared via condensation and curing reaction where the engineering of the solvent results in the nanoparticles with green (λ_em=550 nm) and red emission range (λ_em=650 nm). Differences found in the photophysical properties have been attributed to variations in oligomeric compositions produced during the synthesis as was corroborated by extensive physicochemical characterizations. Specifically, mass spectroscopy provided a picture of the formed species during the synthesis. The feasibility of the oligodots for multi-color imaging is demonstrated both in vitro and in vivo. The red-emitting oligodot is employed for dynamic whole-body imaging in mice. It is envisioned that oligodots would enable multicolor imaging of various biomarkers in complex diseases such as cancer where numerous molecular and metabolic phenotypes work in concert in their emergence.