Detonation nanodiamonds (DNDs) have unique physical and chemical properties that make them invaluable in many applications. However, DNDs are generally assumed to show weak fluorescence, if any, unless chemically modified with organic molecules. We demonstrate that detonation nanodiamonds exhibit significant and excitation-wavelength-dependent fluorescence from the visible to the near-infrared spectral region above 800 nm, even without the engraftment of organic molecules to their surfaces. We show that this fluorescence depends on the surface functionality of the DND particles. The investigated functionalized DNDs, produced from the same purified DND as well as the as-received polyfunctional starting material, are hydrogen, hydroxyl, carboxyl, ethylenediamine, and octadecylamine-terminated. All DNDs are investigated in solution and on a silicon wafer substrate and compared to fluorescent high-pressure high-temperature nanodiamonds. The brightest fluorescence is observed from octadecylamine-functionalized particles and is more than 100 times brighter than the least fluorescent particles, carboxylated DNDs. The majority of photons emitted by all particle types likely originates from non-diamond carbon. However, we locally find bright and photostable fluorescence from nitrogen-vacancy centers in diamond in hydrogenated, hydroxylated, and carboxylated detonation nanodiamonds. Our results contribute to understanding the effects of surface chemistry on the fluorescence of DNDs and enable the exploration of the fluorescent properties of DNDs for applications in theranostics as nontoxic fluorescent labels, sensors, nanoscale tracers, and many others where chemically stable and brightly fluorescent nanoparticles with tailorable surface chemistry are needed.

中文翻译：

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表面化学对爆轰纳米金刚石荧光的影响

爆轰纳米金刚石（DND）具有独特的物理和化学特性，使其在许多应用中具有无价的价值。但是，除非有有机分子进行化学修饰，否则通常认为DND显示弱荧光（如果有的话）。我们证明，爆轰纳米金刚石即使在没有将有机分子植入其表面的情况下，也从可见光到800纳米以上的近红外光谱区域均表现出显着的和激发波长相关的荧光。我们表明，这种荧光取决于DND颗粒的表面功能。由相同的纯化DND以及所获得的多官能起始原料生产的所研究的官能化DND为氢，羟基，羧基，乙二胺和十八烷基胺封端。在溶液中和硅晶片基板上对所有DND进行了研究，并将其与荧光高压高温纳米金刚石进行了比较。从十八烷基胺官能化的颗粒中观察到最亮的荧光，并且比最不荧光的颗粒羧化的DND明亮100倍以上。所有粒子类型发射的大多数光子可能源自非金刚石碳。但是，我们在氢化，羟基化和羧化爆轰纳米金刚石中从金刚石中的氮空位中心局部发现了明亮而光稳定的荧光。我们的研究结果有助于理解表面化学对DND荧光的影响，并能够探索DND的荧光特性，以用于无定形荧光标记，传感器，纳米级示踪剂，