Department of Biological Engineering, College of Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
Int J Mol Sci. 2021 Apr 23;22(9):4433. doi: 10.3390/ijms22094433.
In recent years, fluorescent metal nanoclusters have been used to develop bioimaging and sensing technology. Notably, protein-templated fluorescent gold nanoclusters (AuNCs) are attracting interest due to their excellent fluorescence properties and biocompatibility. Herein, we used an exosome template to synthesize AuNCs in an eco-friendly manner that required neither harsh conditions nor toxic chemicals. Specifically, we used a neutral (pH 7) and alkaline (pH 11.5) pH to synthesize two different exosome-based AuNCs (exo-AuNCs) with independent blue and red emission. Using field-emission scanning electron microscopy, energy dispersive X-ray microanalysis, nanoparticle tracking analysis, and X-ray photoelectron spectroscopy, we demonstrated that AuNCs were successfully formed in the exosomes. Red-emitting exo-AuNCs were found to have a larger Stokes shift and a stronger fluorescence intensity than the blue-emitting exo-AuNCs. Both exo-AuNCs were compatible with MCF-7 (human breast cancer), HeLa (human cervical cancer), and HT29 (human colon cancer) cells, although blue-emitting exo-AuNCs were cytotoxic at high concentrations (≥5 mg/mL). Red-emitting exo-AuNCs successfully stained the nucleus and were compatible with membrane-staining dyes. This is the first study to use exosomes to synthesize fluorescent nanomaterials for cellular imaging applications. As exosomes are naturally produced via secretion from almost all types of cell, the proposed method could serve as a strategy for low-cost production of versatile nanomaterials.
近年来，荧光金属纳米团簇已被用于开发生物成像和传感技术。值得注意的是，由于其出色的荧光特性和生物相容性，基于蛋白质模板的荧光金纳米团簇（AuNCs）引起了人们的兴趣。在此，我们使用外泌体模板以一种既不需要苛刻条件也不需要有毒化学物质的环保方式合成 AuNCs。具体来说，我们使用中性（pH7）和碱性（pH11.5）pH 值来合成两种具有独立蓝色和红色发射的基于外泌体的不同 AuNCs（exo-AuNCs）。通过场发射扫描电子显微镜、能量色散 X 射线微分析、纳米颗粒跟踪分析和 X 射线光电子能谱，我们证明了 AuNCs 在外泌体中成功形成。与蓝色发射的 exo-AuNCs 相比，红色发射的 exo-AuNCs 具有更大的斯托克斯位移和更强的荧光强度。两种 exo-AuNCs 均与 MCF-7（人乳腺癌）、HeLa（人宫颈癌）和 HT29（人结肠癌细胞）兼容，尽管高浓度（≥5mg/mL）的蓝色发射 exo-AuNCs 具有细胞毒性。红色发射的 exo-AuNCs 成功地对细胞核进行了染色，并且与膜染色染料兼容。这是首次使用外泌体合成用于细胞成像应用的荧光纳米材料的研究。由于外泌体是通过几乎所有类型的细胞分泌产生的，因此所提出的方法可以作为低成本生产多功能纳米材料的策略。
