Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117576.
Nanoscale. 2014 Jan 21;6(2):939-45. doi: 10.1039/c3nr04243j.
Near-infrared (NIR) fluorescence signals are highly desirable to achieve high resolution in biological imaging. To obtain NIR emission with high brightness, fluorescent nanoparticles (NPs) are synthesized by co-encapsulation of 2,3-bis(4-(phenyl(4-(1,2,2-triphenylvinyl)phenylamino)phenyl)fumaronitrile (TPETPAFN), a luminogen with aggregation-induced emission (AIE) characteristics, and a NIR fluorogen of silicon 2,3-naphthalocyanine bis(trihexylsilyloxide) (NIR775) using 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] as the encapsulation matrix. The good spectral overlap between the emission of TPETPAFN and the absorption of NIR775 leads to efficient energy transfer, resulting in a 47-fold enhancement of the NIR775 emission intensity upon excitation of TPETPAFN at 510 nm as compared to that upon direct excitation of NIR775 at 760 nm. The obtained fluorescent NPs show sharp NIR emission with a band width of 20 nm, a large Stokes shift of 275 nm, good photostability and low cytotoxicity. In vivo imaging study reveals that the synthesized NPs are able to provide high fluorescence contrast in live animals. The Förster resonance energy transfer strategy overcomes the intrinsic limitation of broad emission spectra for AIE NPs, which opens new opportunities to synthesize organic NPs with high brightness and narrow emission for potential applications in multiplex sensing and imaging.
近红外（NIR）荧光信号在生物成像中具有高分辨率的优势。为了获得具有高亮度的 NIR 发射，通过共包封具有聚集诱导发射（AIE）特性的 2,3-双（4-（（4-（（1,2,2-三苯基乙烯基）苯基氨基）苯基）丁二烯腈（TPETPAFN）和 NIR 荧光团硅 2,3-萘酞菁双（三己基硅氧基）（NIR775），使用 1,2-二硬脂酰基-sn-甘油-3-磷酸乙醇胺-N-[甲氧基（聚乙二醇）-2000]作为包封基质，合成了荧光纳米粒子（NPs）。TPETPAFN 的发射与 NIR775 的吸收之间的良好光谱重叠导致有效的能量转移，从而在 510nm 激发 TPETPAFN 时，与直接在 760nm 激发 NIR775 相比，NIR775 的发射强度增强了 47 倍。所得到的荧光 NPs 具有尖锐的 NIR 发射，带宽为 20nm，Stokes 位移为 275nm，良好的光稳定性和低细胞毒性。体内成像研究表明，合成的 NPs 能够在活体动物中提供高荧光对比度。Förster 共振能量转移策略克服了 AIE NPs 发射光谱较宽的固有限制，为合成具有高亮度和窄发射的有机 NPs 提供了新的机会，为多通道传感和成像的潜在应用开辟了新的机遇。
