Polymethine‐Based Semiconducting Polymer Dots with Narrow‐Band Emission and Absorption/Emission Maxima at NIR‐II for Bioimaging

Abstract

Deep‐penetration fluorescence imaging in the second near‐infrared (NIR‐II) window heralds a new era of clinical surgery, in which high‐resolution vascular/lymphatic anatomy and detailed cancerous tissues can be visualized in real time. Described here is a series of polymethine‐based semiconducting polymers with intrinsic emission maxima in the NIR‐IIa (1300–1400 nm) window and absorption maxima ranging from 1082 to 1290 nm. These polymers were prepared as semiconducting polymer dots (Pdots) in aqueous solutions with fluorescence quantum yields of 0.05–0.18 %, and they demonstrate promising applications in noninvasive through‐skull brain imaging in live mice with remarkable spatial resolution as well as signal‐to‐background contrast. This study offers a platform for future design of NIR‐IIa or even NIR‐IIb emitting Pdots.

Near‐Infrared‐II Semiconducting Polymer Dots for Deep‐tissue Fluorescence Imaging

“…Lately, our group developed Pdots by chemically integrating the semiconducting polymer (PttcÀ SeBTaÀ PFCOOH with the anti-ACQ character) with polymethylene-based NIR-II emissive dyes (NIR1125, NIR1270, and NIR1380). [25] The formed Pdots displayed the absorption ranging from 1082-1290 nm and the emission in the NIR-IIa region (1300-1400 nm) with the QY of 0.05-0.18%. The in vivo real-time through-skull brain imaging in mice paradigm with PttcÀ SeBTaNIR1125 Pdots (traditional NIR-II window) and PttcÀ SeBTaÀ NIR1380 Pdots (NIR-IIb window) revealed the excellent spatial resolution of 0.53-0.61 mm whereas PttcÀ SeBTaÀ NIR1380 Pdots displayed 1.2 times higher SBR (2.32) than that of PttcÀ SeBTaÀ NIR1250 ones , demonstrating the advantage of FI in the NIR-IIb window ( Figure 6).…”

Counterion‐Paired Bright Heptamethine Fluorophores with NIR‐II Excitation and Emission Enable Multiplexed Biomedical Imaging

“…However, both strategies blue‐shift the absorption spectra of the dyes, thus precluding the NIR‐II‐excited multiplexed imaging. A recent study described remarkable anti‐aggregation properties on cyanines imposed by the bulky architecture of semiconducting polymer, however, the capability for multiplexed imaging studies under the excitation of NIR‐II light remains to be examined [12] . Therefore, it is necessary to develop new, bright fluorophores with tunable and well‐shaped NIR‐II absorption and emission spectra for deep‐tissue multiplexed imaging.…”

Biomimetic semiconducting polymer dots for highly specific NIR-II fluorescence imaging of glioma

“…By contrast, increasing attention has been paid to the development of fluorescence imaging techniques for cancer theranostics in the second near-infrared window (NIR-II, 1000–1700) [ [7] , [8] , [9] ]. Since the biological tissues show less autofluorescence in NIR-II window than that in the visible (400–700 ​nm) or the first near-infrared window (NIR-I, 700–900) [ [10] , [11] , [12] , [13] ], NIR-II fluorescent probes can visualize the biological tissues with high temporal/spatial resolution and deep penetration [ [14] , [15] , [16] ]. However, most of the potential fluorescent probes do not exhibit a fluorescence signal in NIR-II window.…”