Molecular Engineering and Design of Semiconducting Polymer Dots with Narrow-Band, Near-Infrared Emission for in Vivo Biological Imaging

Abstract

This article describes the design and synthesis of donor-bridge-acceptor-based semiconducting polymer dots (Pdots) that exhibit narrow-band emissions, ultrahigh brightness, and large Stokes shifts in the near-infrared (NIR) region. We systematically investigated the effect of π-bridges on the fluorescence quantum yields of the donor-bridge-acceptor-based Pdots. The Pdots could be excited by a 488 or 532 nm laser and have a high fluorescence quantum yield of 33% with a Stokes shift of more than 200 nm. The emission full width at half-maximum of the Pdots can be as narrow as 29 nm, about 2.5 times narrower than that of inorganic quantum dots at the same emission wavelength region. The average per-particle brightness of the Pdots is at least 3 times larger than that of the commercially available quantum dots. The excellent biocompatibility of these Pdots was demonstrated in vivo, and their specific cellular labeling capability was also approved by different cell lines. By taking advantage of the durable brightness and remarkable stability of these NIR fluorescent Pdots, we performed in vivo microangiography imaging on living zebrafish embryos and long-term tumor monitoring on mice. We anticipate these donor-bridge-acceptor-based NIR-fluorescent Pdots with narrow-band emissions to find broad use in a variety of multiplexed biological applications.

Semiconducting Polymer Nanocavities: Porogenic Synthesis, Tunable Host–Guest Interactions, and Enhanced Drug/siRNA Delivery

“…Semiconductor polymer dots (Pdots) exhibit tunable fluorescence, high brightness, and excellent photostability for optical imaging and sensing applications . The superior properties of Pdots have been widely demonstrated by cellular labeling, in vivo imaging, single‐particle tracking, and various bioassays . Recently, the extraordinary light absorption of semiconducting polymers was used as a basis for developing multifunctional probes for photoacoustic imaging and photothermal therapy .…”

Polymer Dots as Effective Phototheranostic Agents

“…Pdots as ideal fluorescence imaging agents should have the following features: (1) high stability; (2) bright fluorescence signal; and (3) excellent biocompatibility. Considering the merits of weak scattering, autofluorescence interference and deep tissue penetration, near‐infrared (NIR) emissive Pdots with narrow emission width were developed for the multiplexing imaging technique, such as flow cytometry and cell sorting, immunofluorescence or nucleic acid analysis . We discuss the progress of the use of Pdots for fluorescence imaging.…”

Semiconducting polymer dots as near‐infrared fluorescent probes for bioimaging and sensing

“…[47] Copyright 2018, American Chemical Society 3%) incorporated into Pdots would induce severe selfquenching effect, but the one with bulky groups did not suffer from this drawback. [34] By taking advantage of the interchain energy transfer, Pdot 6 (PF-TC 6 FQ-BODIPY) Pdots exhibit narrower NIR emission and are three times brighter than the commercial quantum dots at similar emission range (Qdot705). However, the relatively low ratios of NIR chromophores to the polymer could weaken photostability under highenergy excitation.…”

“…(a) Fluorescence spectra of Pdot 18, Pdot 23, and Pdot 1 in water. Reproduced with permission [34]. Scale bar, 20 mm.…”