Near-Infrared Fluorescent Dye-Doped Semiconducting Polymer Dots

Abstract

Near-infrared (NIR) fluorescence sensing is desirable for in vivo biological measurements. But the method is currently limited by the availability of NIR fluorescent markers as well as by their poor performance, such as self-aggregation and dim fluorescence, in a physiological environment. To address this issue, this paper describes a NIR fluorescent polymer dot (Pdot) that emits at 777 nm. This Pdot was comparable in size to a water-soluble NIR quantum dot that emits at 800 nm (ITK Qdot800) but was about 4 times brighter and with a narrower emission peak. We formed the NIR Pdot by doping the NIR dye, silicon 2,3-naphthalocyanine bis(trihexylsilyloxide) (NIR775), into the matrix of poly (9,9-dioctylfluorene-co-benzothiadiazole) (PFBT) as the Pdot formed using a nanoscale precipitation technique. Free molecules of NIR775 aggregate in aqueous solution but encapsulating them into the hydrophobic Pdot matrix effectively introduced them into aqueous solution for use in biological studies. Most importantly, the brightness of NIR775 was dramatically enhanced because of the excellent light harvesting ability of PFBT and the very efficient energy transfer from PFBT to NIR775. We anticipate this bright NIR Pdot will be useful in biological measurements and cellular imaging where strong NIR emission is beneficial.

Near-Infrared Fluorescent Semiconducting Polymer Dots with High Brightness and Pronounced Effect of Positioning Alkyl Chains on the Comonomers

“…6 Table 2). Experimentally we further performed measurements of singleparticle brightness in which the measured average per-particle brightness of PFBT-DBSOC610 Pdots ( Figure 3B) was indeed ~2 times higher than that of Qdots® 705 ( Figure 3A 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 14 conjugates were sequentially incubated with the cells.…”

“…6,[33][34][35][36][37][38][39][40][41][42][43][44][45][46] Despite the enormous progress, the synthesis of suitable NIR fluorescent semiconducting polymers for generating Pdots is still a significant challenge, partially because of the rigid and flat extended -conjugated skeletons of NIR polymers that result in the serious self-quenching upon condensation into a Pdot form. 47-51 Accordingly, there have been several approaches developed to address the aforementioned challenge.…”

“…For example, Chiu's group embedded the NIR dye, silicon 2,3-naphthalocyanine bis(trihexylsilyloxide), into the matrix of poly (9,9-dioctylfluorene-co-benzothiadiazole) (PFBT) Pdots. 6 The efficient energy transfer from the PFBT matrix to the NIR dyes has greatly increased the fluorescence brightness of the NIR dyes. Similarly, Zhang et al blended more than three kinds of conjugated polymers together with the optimized molar ratio inside a Pdot where the NIR emission 6 could be accomplished via cascade Förster resonance energy transfer (FRET).…”

“…6 The efficient energy transfer from the PFBT matrix to the NIR dyes has greatly increased the fluorescence brightness of the NIR dyes. Similarly, Zhang et al blended more than three kinds of conjugated polymers together with the optimized molar ratio inside a Pdot where the NIR emission 6 could be accomplished via cascade Förster resonance energy transfer (FRET). 52 In these two studies, however the potential leaching of the encapsulated dyes/polymers remains an important concern due to the lack of stable covalent linkages between the doped molecules and the Pdot matrix, which would greatly influence the photophysical properties of Pdots.…”

Stark fluoreszierende halbleitende Polymerpunkte für Biologie und Medizin

“…[61] Stark fluoreszierende P-PunktSpezies mit breiter Absorption und Emission im NIR-Bereich sind für In-vivo-Anwendungen bevorzugt, da biologische Gewebe diese Wellenlängen in minimalem Ausmaß absorbieren. Diese Anforderungen bieten eine Vielzahl von Forschungsmçglichkeiten für Polymerchemiker, um neue Polymerspezies mit engbandigen und/oder NIR-Emissionen zu untersuchen.…”