Nanodiamonds and Their Applications in Cells

Abstract

Diamonds owe their fame to a unique set of outstanding properties. They combine a high refractive index, hardness, great stability and inertness, and low electrical but high thermal conductivity. Diamond defects have recently attracted a lot of attention. Given this unique list of properties, it is not surprising that diamond nanoparticles are utilized for numerous applications. Due to their hardness, they are routinely used as abrasives. Their small and uniform size qualifies them as attractive carriers for drug delivery. The stable fluorescence of diamond defects allows their use as stable single photon sources or biolabels. The magnetic properties of the defects make them stable spin qubits in quantum information. This property also allows their use as a sensor for temperature, magnetic fields, electric fields, or strain. This Review focuses on applications in cells. Different diamond materials and the special requirements for the respective applications are discussed. Methods to chemically modify the surface of diamonds and the different hurdles one has to overcome when working with cells, such as entering the cells and biocompatibility, are described. Finally, the recent developments and applications in labeling, sensing, drug delivery, theranostics, antibiotics, and tissue engineering are critically discussed.

Chemical Functionalization of Nanodiamonds: Opportunities and Challenges Ahead

“…[4] These defects that are incorporated into the sp 3 structure, called color centers,correspond to new atoms or vacancies in the lattice and produce fluorescence NDs,m aking them suitable for uses in electronics and bioimaging.C urrently,d ifferent ND technologies in lubricant and polymer science have already reached late-stage trials,a nd few of them are commercially available. [5] However,i n some other fields such as biomedicine, several challenges still need to be faced before as afe application of ND-based technologies reaches the market. Moreover,t here is still room for improvement regarding purification and functionalization protocols.F or instance,D -NDs require extensive postsynthesis modifications to obtain stable dispersions,w hile doping generally needs high temperatures,w hich is incompatible with most of the surface treatments.F or these reasons,d ifferent multi-functionalization protocols have been recently explored, proving how crucial the tailoring of the synthetic and functionalization strategies to expand ND applications is.Inthis Minireview we will critically focus on the preparation and chemical functionalization of NDs,p articularly predicting their applications in the biological and biomedical fields.…”

Cell Uptake of Lipid‐Coated Diamond

“…Fluorescent nanodiamonds (FNDs) are a promising material for various biomedical applications including drug delivery, therapeutics, and imaging . FNDs have superior physical and chemical properties including hardness and Young's modulus, high thermal conductivity and electrical resistivity, chemical stability and resistance to harsh environments, and good biocompatibility . Nitrogen vacancy (NV) centers in FNDs, atomic‐sized defects with stable fluorescence, possess outstanding optical and magnetic properties .…”

“…[1,2] FNDs have superior physical and chemical properties including hardness and Young's modulus, high thermal conductivity and electrical resistivity, chemical stability and resistance to harsh environments, and good biocompatibility. [1,3] Nitrogen vacancy (NV) centers in FNDs, atomic-sized defects with stable fluorescence, possess outstanding optical and magnetic properties. [4][5][6] The fluorescence is perfectly stable, which qualifies FNDs as interesting biolabels.…”

Transferrin‐Coated Nanodiamond–Drug Conjugates for Milliwatt Photothermal Applications

“…[7] The best studied color center is the nitrogen-vacancy (NV) center. [2,3,[8][9][10][11] The remarkable properties of this atom-like defect in the diamond lattice allow application for high-resolution magnetic (bio)sensing, [12] energy transfer, [13] bioimaging, [12] and even quantum computing technologies. [14] Due to this, in the present work, nanodiamonds with NV centers were selected as base material for designing a potent theranostic system.…”

“…To alleviate this primary issue, nanodiamond coating technologies have been developed using adsorption mechanisms deriving from weak attractive forces (electrostatic, van der Waals, hydrogen bonding) and/or strong covalent interactions. [8,16,17] However, these coating technologies have persistent difficulties due to batch to batch production variability impacting the surface composition of NDs. In addition, it is crucial to understand that the coating material has to fulfill many important criteria, including 1) chemical multifunctionality, 2) reproducibility of the coating strategy on NDs from different sources and sizes, 3) colloidal stability of the fND conjugate in biological media and inside cells, and 4) minimally affecting the photoluminescence and magnetic sensing capabilities.…”