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近红外荧光成像具有低背景荧光干扰、强组织穿透力和对生物机体无光损伤等优点,因此发展具有良好生物相容性、量子产率高、化学及光稳定性好的水溶性长波段近红外荧光探针成为目前的研究热点.与有机近红外荧光染料相比,无机纳米近红外荧光探针因其具有较高的摩尔消光吸光系数和荧光量子产率、抗光漂白能力强、发射光谱集中且可调等特点而备受重视.采用N-异丁酰基-L(D)-半胱氨酸(N-isobutyryl-L(D)-cysteine,L(D)-NIBC)手性对映异构体作为还原剂和稳定剂一步法直接制备得到两种平均粒径小于2 nm的水溶性手性金纳米团簇(L-NIBC-Au NCs和D-NIBC-Au NCs).CD光谱显示二者在230~360 nm波段的圆二色性完美对称,荧光光谱显示二者均在900~1000 nm的近红外波段具有较强的荧光发射峰,且二者的荧光量子产率分别达到6.9%(L-NIBC-Au NCs)和8.2%(D-NIBC-Au NCs),细胞毒性实验表明这两种手性金纳米团簇均无细胞毒性.上述结果表明两种手性金纳米团簇不仅符合成为近红外荧光探针的基本要求,而且还具有不对称光学活性和潜在的手性识别能力等独特性质.手性金纳米团簇具有成为一类全新的近红外荧光探针的潜力,为将来实现对特定分子通过手性识别来进行体内近红外荧光示踪和成像提供了全新的思路.
Near-infrared fluorescence imaging has the advantages of low background fluorescence interference, strong tissue penetration and no damage to the biological body. Therefore, the development of water-soluble long-wavelength band with good biocompatibility, high quantum yield, good chemical and light stability Near-infrared fluorescence probe has become the research hotspot.Compared with organic near-infrared fluorescent dye, inorganic nano-near-infrared fluorescence probe has high molar extinction extinction coefficient and fluorescence quantum yield, strong anti-photobleaching capability, emission The concentration and tunability of the spectra have attracted much attention.Using the chiral pair of N-isobutyryl-L (D) -cysteine, L (D) -NIBC Two kinds of water-soluble chiral gold nanoclusters (L-NIBC-Au NCs and D-NIBC-Au NCs) with average particle diameter less than 2 nm were prepared by one-step enantiomers as reductant and stabilizer. The results show that the two have perfect symmetry of circular dichroism in the band of 230-360 nm. The fluorescence spectra show that both of them have strong fluorescence emission peaks in the near infrared band of 900 ~ 1000 nm, and the fluorescence quantum yields of the two are respectively 6.9% (L-NIBC-Au NCs) and 8.2% (D-NIBC-Au NCs). Cytotoxicity experiments showed that these two kinds of hands The results showed that the two chiral gold nanoclusters not only meet the basic requirements of becoming a near-infrared fluorescent probe, but also possess unique properties such as asymmetric optical activity and potential chiral recognition ability. The potential of chiral gold nanoclusters to become a new class of near-infrared fluorescent probes has provided a new idea for the future implementation of near-infrared fluorescent tracing and imaging of specific molecules through chiral recognition in vivo.