State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.
International Joint Research Laboratory for Biointerface and Biodetection, Jiangnan University, Wuxi, 214122, China.
Nat Commun. 2017 Nov 29;8(1):1847. doi: 10.1038/s41467-017-01337-2.
The intra- and extracellular positioning of plasmonic nanoparticles (NPs) can dramatically alter their curative/diagnostic abilities and medical outcomes. However, the inability of common spectroscopic identifiers to register the events of transmembrane transport denies their intracellular vs. extracellular localization even for cell cultures. Here we show that the chiroptical activity of DNA-bridged NP dimers allows one to follow the process of internalization of the particles by the mammalian cells and to distinguish their extra- vs intra-cellular localizations by real-time spectroscopy in ensemble. Circular dichroism peaks in the visible range change from negative to positive during transmembrane transport. The chirality reversal is associated with a spontaneous twisting motion around the DNA bridge caused by the large change in electrostatic repulsion between NPs when the dimers move from interstitial fluid to cytosol. This finding opens the door for spectroscopic targeting of plasmonic nanodrugs and quantitative assessment of nanoscale interactions. The efficacy of dichroic targeting of chiral nanostructures for biomedical applications is exemplified here as photodynamic therapy of malignancies. The efficacy of cervical cancer cell elimination was drastically increased when circular polarization of incident photons matched to the preferential absorption of dimers localized inside the cancer cells, which is associated with the increased generation of reactive oxygen species and their preferential intracellular localization.
等离子体纳米粒子（NPs）的细胞内外定位可以显著改变它们的治疗/诊断能力和医疗效果。然而，常见的光谱标识符无法记录跨膜转运事件，这使得即使对于细胞培养物，也无法确定它们是在细胞内还是细胞外定位。在这里，我们展示了 DNA 桥接 NP 二聚体的手性活性可以使人们通过哺乳动物细胞跟踪粒子的内化过程，并通过实时光谱法在整体上区分其细胞外和细胞内定位。在跨膜转运过程中，可见范围内的圆二色性峰从负变为正。手性反转与 NP 之间的静电排斥发生巨大变化时，二聚体从间隙液移动到细胞质时，DNA 桥周围自发扭曲运动有关。这一发现为等离子体纳米药物的光谱靶向和纳米级相互作用的定量评估开辟了道路。这里以光动力疗法治疗恶性肿瘤为例，展示了手性纳米结构的圆二色性靶向在生物医学应用中的功效。当入射光子的圆偏振与二聚体在癌细胞内的优先吸收相匹配时，宫颈癌细胞的消除效率大大提高，这与活性氧的产生增加及其优先的细胞内定位有关。
