A BODIPY-Based Donor/Donor-Acceptor System: Towards Highly Efficient Long-Wavelength-Excitable Near-IR Polymer Dots with Narrow and Strong Absorption Features

Bright long-wavelength-excitable semiconducting polymer dots (LWE-Pdots) are highly desirable for invivo imaging and multiplexed invitro bioassays. LWE-Pdots have been obtained by incorporating a near-infrared (NIR) emitter into the backbone of a polymer host to develop a binary donor-acceptor (D-A) system. However, they usually suffer from severe concentration quenching and a trade-off between fluorescence quantum yield (Phi(f)) and absorption cross-section (sigma). Herein, we describe a ternary component (D-1/D-2-A) strategy to achieve ultrabright, green laser-excitable Pdots with narrow-band NIR emission by introducing a BODIPY-based assistant polymer donor as D-1. The D-1/D-2-A Pdots possess improved Phi(f) and sigma compared to corresponding binary D-2-A Pdots. Their Phi(f) is as high as 40.2%, one of the most efficient NIR Pdots reported. The D-1/D-2-A Pdots show ultrahigh single-particle brightness, 83-fold brighter than Qdot 705 when excited by a 532nm laser. When injected into mice, higher contrast invivo tumor imaging was achieved using the ternary Pdots versus the binary D-A Pdots.