Nanodiamonds are tiny diamond particles, typically 2 to 20 nanometers across, with the same carbon crystal structure as a gemstone diamond but small enough that millions could fit on the period at the end of this sentence. They’re one of the most versatile nanomaterials in use today, showing up in drug delivery research, semiconductor polishing, advanced coatings, and thermal management for electronics. The global nanodiamond market hit roughly $415 million in 2025, with healthcare and pharmaceuticals accounting for the largest share.
Size and Structure
A nanodiamond’s core is made of carbon atoms arranged in the same cubic lattice found in bulk diamond. That lattice is what gives diamond its famous hardness and thermal conductivity, and those properties carry over to the nanoscale. Most commercially produced nanodiamonds cluster around 4 to 5 nanometers in diameter, though the full range runs from about 1 nanometer up to around 20.
At sizes below 5 nanometers, the particles start behaving differently from larger diamonds in subtle but important ways. The surface of the crystal becomes a larger proportion of the total structure, introducing distortions and imperfections that change how the particle interacts with light and with other materials. High-resolution electron microscopy has revealed that these ultra-small particles show unusual diffraction patterns, essentially optical fingerprints that don’t appear in bigger diamonds, because surface atoms make up so much of the particle that the crystal’s symmetry breaks down slightly.
How Nanodiamonds Are Made
The most common production method is detonation synthesis. A mixture of explosives (typically TNT and RDX) with a negative oxygen balance is detonated inside a sealed chamber. The extreme pressure and temperature of the blast, lasting only microseconds, force carbon atoms into the diamond crystal structure. The resulting soot contains nanodiamond particles that are then purified from the other carbon debris and metal residues left over from the explosion.
Detonation nanodiamonds tend to have a characteristic size distribution centered around 5 nanometers, with some particles as small as 2 nanometers. Isolating the very smallest particles requires ultracentrifugation, and even then, only a tiny fraction (about 0.01% by weight) of sub-4 nanometer diamonds can be separated out. Researchers have found that using nanostructured explosive charges, rather than conventional ones, produces smaller diamonds overall. The key factor is the discontinuity of the explosive at the nanoscale level.
The second major method uses high pressure and high temperature (HPHT) to crush larger diamond material down to nanoparticle size. HPHT nanodiamonds have notably better crystal quality than detonation nanodiamonds. Their internal structure closely matches that of a perfect single-crystal diamond, while detonation nanodiamonds tend to contain more defects, stress, and a transitional layer between the diamond core and a slightly disordered surface. The tradeoff is that HPHT particles commercially available today are generally larger, with a typical median size around 18 nanometers, though laboratory techniques have pushed them below 5 nanometers with careful size selection.
Both methods produce raw powders that contain impurities: metal oxides from grinding equipment in HPHT, and residues from the blast chamber in detonation synthesis. Purification is a necessary step before the particles are useful.
What Makes the Surface Special
A nanodiamond’s surface is covered with chemical groups that make it easy to attach other molecules. Acid treatment, the most common purification step, naturally generates a mix of oxygen-containing groups on the surface, including carboxylic acids, alcohols, ketones, and others. Carboxylic acid groups are particularly useful because they serve as reliable anchoring points for attaching drugs, proteins, or targeting molecules.
Researchers can further enrich the surface with specific groups to improve consistency and attachment efficiency. In one approach, increasing the proportion of carboxylic acid groups on fluorescent nanodiamonds made them more uniform and significantly improved the efficiency of attaching biotin, a molecule commonly used as a biological linking agent. This kind of surface tuning is what makes nanodiamonds so adaptable: the diamond core provides stability and optical properties, while the surface chemistry can be customized for a specific job.
Built-In Fluorescence
Some nanodiamonds glow when you shine a laser on them, and they do it without fading over time. This fluorescence comes from a specific defect in the crystal called a nitrogen vacancy center: a spot where a nitrogen atom sits next to a missing carbon atom in the lattice. When light hits this defect, it absorbs energy and re-emits it as fluorescence.
This is a significant advantage over conventional fluorescent dyes, which degrade and stop glowing after prolonged light exposure (a problem called photobleaching). Nitrogen vacancy centers are embedded in the rigid diamond lattice, so they’re physically protected and can fluoresce essentially indefinitely. The brightness and color of the fluorescence depend on the charge state of the defect, which can shift between a brightly fluorescent negative state and a dimmer neutral state depending on the local chemical environment. Researchers are working on stabilizing the brighter state for use in biological imaging and quantum sensing.
Medical and Drug Delivery Uses
Nanodiamonds are more biocompatible and show lower toxicity to cells than other carbon-based nanomaterials like carbon nanotubes and graphene. In laboratory cell studies, they consistently show high biocompatibility, though like all insoluble nanoparticles, they can trigger some production of reactive oxygen species inside cells. The degree of any toxic effect depends on particle properties and how long cells are exposed.
The most promising medical application is drug delivery, particularly for cancer treatment. Nanodiamonds can carry chemotherapy drugs directly to tumors, potentially increasing effectiveness while reducing side effects elsewhere in the body. In one line of research, nanodiamonds were covalently linked to paclitaxel, a widely used cancer drug, and shown to effectively inhibit tumor growth in both cell cultures and animal models of lung cancer and colorectal cancer. The drug-loaded nanodiamonds blocked cancer cell division, disrupted chromosome separation, and triggered programmed cell death.
Taking this further, researchers have loaded nanodiamonds with both paclitaxel and cetuximab, an antibody that targets a specific receptor found on colorectal cancer cells. This co-delivery approach enhanced tumor inhibition beyond what either agent achieved alone, because the antibody helped direct the particle to the right cells while the drug killed them. The nanodiamond essentially acts as a multi-purpose delivery vehicle, carrying different therapeutic agents simultaneously.
Industrial and Electronics Applications
Outside of medicine, the largest demand for nanodiamonds comes from electronics, precision polishing, lubrication, and advanced coatings. In semiconductor manufacturing, nanodiamonds are used to polish wafers and components to extremely smooth finishes, a critical step as chip features continue to shrink.
Thermal management is another growing application. Electronics generate heat, and the materials surrounding chips need to conduct that heat away efficiently. Most polymer-based packaging materials are poor thermal conductors, typically below 0.2 watts per meter-kelvin. By embedding nanodiamond particles into these polymers, researchers have dramatically improved heat transfer. In one study, an epoxy composite filled with nanodiamond-graphite hybrids reached a thermal conductivity of 2.48 watts per meter-kelvin, an improvement of over 1,200% compared to the plain epoxy. The nanodiamond particles create additional heat-conducting pathways through the material while also strengthening it mechanically.
The nanodiamond market is projected to nearly triple by 2034, reaching about $1.14 billion, driven largely by expanding use in electronics packaging, industrial coatings, and biomedical engineering.