School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China.
Nanoscale. 2018 Sep 27;10(37):18064-18073. doi: 10.1039/c8nr05878d.
In recent years, polydopamine (PDA) nanoparticles have attracted considerable attention in different research fields because of their many fascinating physicochemical properties. However, as an analogue of naturally occurring melanin, PDA nanoparticles (PDANPs) typically exhibit weak fluorescence properties. Herein, we report a facile one-pot method for synthesizing bright blue luminescent PDANPs through the redox modulation of PDA surface chemistry. The composition and morphology of the resultant NPs were systematically characterized by transmission electron microscopy and several spectroscopy methods, which verified the successful fabrication of PDANPs. More importantly, comparative chemical analysis of dopamine polymerization revealed the significant impacts of synthesis conditions and PDA surface chemistry on the luminescence properties of PDANPs. Remarkably, in addition to their excellent water-solubility, salt-tolerance and high photostability under extreme pH conditions, the as-prepared PDANPs possess the highest quantum yield (5.1%) among all the reported intrinsic fluorescent PDANPs. Moreover, based on the coordination interaction between phenolic hydroxyl groups of PDANPs and ferric ions (Fe3+), the synthesized PDANPs were successfully utilized as a turn-off sensing platform for sensitive and selective detection of Fe3+ without using any additional targeting molecules. Upon increasing the Fe3+ concentration in the range from 0.5 to 20 μM, the fluorescence intensity of PDANPs decreased linearly. The detection limit of Fe3+ was 0.15 μM. Finally, this fluorescent sensor was successfully used to determine Fe3+ in natural water samples, showing good prospects for practical applications and may pave the way for the development of new rational methodologies for further enhancing the intrinsic fluorescence of PDA and fabricating other novel fluorescent organic nanoparticles.
近年来，由于具有许多迷人的物理化学性质，聚多巴胺（PDA）纳米粒子在不同的研究领域引起了相当大的关注。然而，作为天然存在的黑色素的类似物，PDA 纳米粒子（PDANPs）通常表现出较弱的荧光性质。在此，我们报告了一种简便的一锅法，通过 PDA 表面化学的氧化还原调节来合成亮蓝色发光的 PDANPs。通过透射电子显微镜和几种光谱方法系统地表征了所得 NPs 的组成和形态，验证了 PDANPs 的成功制备。更重要的是，对多巴胺聚合的比较化学分析表明，合成条件和 PDA 表面化学对 PDANPs 的荧光性质有显著影响。值得注意的是，除了具有出色的水溶性、耐盐性和在极端 pH 条件下的高光稳定性外，所制备的 PDANPs 的量子产率（5.1%）在所有报道的内在荧光 PDANPs 中最高。此外，基于 PDANPs 的酚羟基与铁离子（Fe3+）之间的配位相互作用，所合成的 PDANPs 成功用作无任何额外靶向分子的 Fe3+的灵敏和选择性检测的关闭感应平台。当 Fe3+浓度在 0.5 至 20 μM 的范围内增加时，PDANPs 的荧光强度线性降低。Fe3+的检测限为 0.15 μM。最后，该荧光传感器成功用于测定天然水样中的 Fe3+，显示出良好的实际应用前景，并可能为进一步增强 PDA 的本征荧光和制造其他新型荧光有机纳米粒子开辟新的合理方法的发展铺平道路。
