Benchtop Fluorination of Fluorescent Nanodiamonds on a Preparative Scale: Toward Unusually Hydrophilic Bright Particles

Abstract

Fluorination of diamonds modulates their optical and electromagnetic properties and creates surfaces with increased hydrophobicity. In addition, fl uorination of diamonds and nanodiamonds has been recently shown to stabilize fl uorescent nitrogen-vacancy centers, which can serve as extremely sensitive single atomic defects in a vast range of sensing applications from quantum physics to high-resolution biological imaging. Traditionally, fl uorination of carbon nanomaterials has been achieved using harsh and complex experimental conditions, creating hydrophobic interfaces with diffi cult dispersibility in aqueous environments. Here, a mild benchtop approach to nanodiamond fl uorination is described using selective Ag + -catalyzed radical substitution of surface carboxyls for fl uorine. In contrast to other approaches, this highyielding procedure does not etch diamond carbons and produces a highly hydrophilic interface with mixed C−F and C−OH termination. This dual functionalization of nanodiamonds suppresses detrimental hydrophobic interactions that would lead to colloidal destabilization of nanodiamonds. It is also demonstrated that even a relatively low surface density of fl uorine contributes to stabilization of negatively charged nitrogen-vacancy centers and boosts their fl uorescence. The simultaneous control of the surface hydrophilicity and the fl uorescence of nitrogen-vacancy centers is an important issue enabling direct application of fl uorescent nanodiamonds as nanosensors for quantum optical and magnetometry measurements operated in biological environment.

Optical imaging of localized chemical events using programmable diamond quantum nanosensors

“…1b). The NDs used are in average ∼33 nm in diameter with a fairly narrow size distribution41 (Supplementary Fig. 1) and coated with a HPMA shell a few nanometre thick, as indicated by transmission electron microscopy (TEM) image (Fig.…”

Not All Fluorescent Nanodiamonds Are Created Equal: A Comparative Study

“…It is known that near‐surface NV centers strongly interact with the diamond surface and the functional groups present there . Fluorescence from these centers can be quenched, or their fluorescence properties at least significantly altered due to this interaction . NV centers separated less than about 10 nm are generally assumed to interact with the surface .…”

Extremely rapid isotropic irradiation of nanoparticles with ions generated in situ by a nuclear reaction

“…Although the spectral shapes and overall fluorescence of our FNDs were very similar to those of FNDs irradiated in an accelerator, we were interested in whether our procedure increases the homogeneity of irradiation, i.e., whether the material contains a higher fraction of FNDs. To distinguish the fluorescent and non-fluorescent NDs present in a large ensemble at the single-particle level 19 , 66 , we utilized simultaneous measurement of fluorescence-lifetime imaging microscopy (FLIM) and atomic force microscopy (AFM) (Supplementary Figure 7 ). We found that the fraction of FNDs in material irradiated in a nuclear reactor increased by a factor of 2.6 compared to optimally 41 p + -irradiated pellet target with NDs in an accelerator (49% vs. 19%).…”