Photoluminescent Diamond Nanoparticles for Cell Labeling: Study of the Uptake Mechanism in Mammalian Cells

Abstract

Diamond nanoparticles (nanodiamonds) have been recently proposed as new labels for cellular imaging. For small nanodiamonds (size <40 nm), resonant laser scattering and Raman scattering cross sections are too small to allow single nanoparticle observation. Nanodiamonds can, however, be rendered photoluminescent with a perfect photostability at room temperature. Such a remarkable property allows easier single-particle tracking over long time scales. In this work, we use photoluminescent nanodiamonds of size <50 nm for intracellular labeling and investigate the mechanism of their uptake by living cells. By blocking selectively different uptake processes, we show that nanodiamonds enter cells mainly by endocytosis, and converging data indicate that it is clathrin-mediated. We also examine nanodiamond intracellular localization in endocytic vesicles using immunofluorescence and transmission electron microscopy. We find a high degree of colocalization between vesicles and the biggest nanoparticles or aggregates, while the smallest particles appear free in the cytosol. Our results pave the way for the use of photoluminescent nanodiamonds in targeted intracellular labeling or biomolecule delivery.

Nanodiamond for intracellular imaging in the microorganisms in vivo

“…The distribution of intensity of ND and LysoTracker fluorescence along cross-section (along the line in Figure 5IIa, b) of the T. thermophile vacuole is shown in the Figure 5III, revealing the ND localization inside the food vacuole. It is comparable with observation of the cellular model (RAW, this work, and others [19,20]). ND is perceived as food by cell and microorganism and is isolated (pick-up) from the intercellular medium.…”

“…The positions of lysosomes are shown separately in red in Figure 3b; and ND in green in Figure 3c. ND co-localized with lysosomes is observed (in yellow as the mix of green and red), the observation agrees with previous findings [19,20]. Images in Figure 3 also demonstrate the possibility to use ND for the cell imaging and labeling, using nanodiamond's natural fluorescence for detection.…”

“…The characteristics of ND engulfement by cells [19,20] and microorganism, which has the digestive system [24], have been already discussed. Refer to Figure 8, Here the ND entering the microorganism carrying by foreign object is demonstrated.…”

“…trate into the cells via endocytotic pathways, and accumulate inside [19,20]. This allows transporting drug inside the cells.…”

Electrochemical Preparation of Color-Tunable Fluorescent Carbon Quantum Dots

“…525 nm 附近, 没有移动. 前者的荧光发射机理与已经 报道的碳量子点相同 [5,6,11] , 是由于碳量子点上 π-π 共轭 体系的大小所致 [12] ; 而后者的荧光来源则与量子点的 大小无关, 是由于量子点表面缺陷所引起的 [12] . 在紫外 灯(365 nm)的照射下, 可以看到碳量子点发出黄色荧光 …”