Highly Fluorescent Nanodiamonds Protein‐Functionalized for Cell Labeling and Targeting

Abstract

Fluorescent nanodiamond (FND) is attracting much attention as a bioimaging agent because of its inherent biocompatibility and superior optical properties (e.g., excellent photostability and far‐red emission). However, for practical use in life science research, some issues such as higher brightness and ease of bioconjugation have to be solved. Here, it is shown that the 100‐nm FND particles fabricated by using nitrogen‐rich type Ib diamonds and high‐energy proton irradiation are highly fluorescent and readily functionalizable with proteins for biological applications. In the first approach, acid‐treated FND is noncovalently coated with glycoproteins or neoglycoproteins (i.e., proteins chemically modified with multiple sugar residues) for targeting hepatocytes via carbohydrate receptors. In the second approach, FND is first PEGylated and then covalently conjugated with streptavidin, to which biotin‐labeled antibodies of interest are linked. High targeting specificity of the bioconjugated FND is demonstrated with the human hepatoma cell line, HepG2, and breast cancer cell lines, ASB145‐1R, MCF‐7, and MDA‐MB‐231 cells. These approaches should be widely applicable to a variety of situations for specific targeting and labeling of cells.

Germanium-Vacancy Color Center in Diamond as a Temperature Sensor

“…In addition, the surface passivation of diamond nanoparticles is well developed [12][13][14][15][16] enabling selective attachment of nanodiamonds to specific organelles of the cell, and therefore, in vivo measurement of their temperature response under various conditions.…”

Nanodiamond: A high impact nanomaterial

“…Unlike other nanocarbon species such as carbon nanotubes (CNTs), nanodiamonds feature a rich surface chemistry resulting from the synthesis and purification steps and this provides a platform for a number of subsequent functionalization schemes. A number of interesting functionalization schemes have been developed for tailoring the surface groups of NDs, including amino functionalities for bioapplications [60] and attachment of biotin [61], streptavidin [61,62], and peptide nucleic acids (PNA) [63], among others. These functionalities, and many others, demonstrate that NDs can be functionalized with a wide variety of groups, and are thus suitable for potential application in a number of environments -of particular interest is targeted delivery to cell membranes for imaging, drug delivery, or even surgery.…”

High-Frequency Electron Paramagnetic Resonance Spectroscopy of Nitroxide-Functionalized Nanodiamonds in Aqueous Solution

“…In many of those applications, functional biological molecules need to be tailored to the ND surfaces. Even though many approaches to attach biological molecules to ND surfaces have been investigated [5,8,12,[14][15][16], it remains challenging to monitor behaviors of the grafted molecules because the presence of ND hampers the employment of standard techniques (e.g., chromatography and optical spectroscopy).…”

“…In addition, in a majority of cases, NDs contain nitrogen-vacancy (NV) centers, which are atomicscale fluorescent defects with excellent quantum properties. Thus, ND is a promising material for applications of biological imaging, targeted drug delivery, and nano-scale sensing [1][2][3][4][5][6][7][8][9][10][11][12][13]. In many of those applications, functional biological molecules need to be tailored to the ND surfaces.…”