Gold nanoparticles are among the most widely used nanomaterials because their size, shape, surface chemistry, and surrounding environment can be engineered to control their physical, optical, and interfacial properties. These characteristics make gold nanoparticles useful across diagnostics, biomedical research, sensing, spectroscopy, and optical engineering.
Spherical gold nanoparticles are often recognized by their characteristic red color, which arises from their interaction with visible light. Changing particle size or morphology can alter absorption, scattering, and plasmon resonance across the visible and near-infrared spectrum. Learn more about the physical properties and optical properties of gold nanoparticles.
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Explore gold nanospheres, nanoshells, and nanorods across a range of sizes and surface chemistries.
Gold Nanoparticle Applications
Gold nanoparticles combine tunable optical properties with flexible surface chemistry and colloidal stability, enabling their use across a wide range of research and product-development applications.
Diagnostic Applications
Gold nanoparticles are widely used as reporter particles in diagnostic assays because they produce a strong visible signal and can be functionalized with antibodies, proteins, oligonucleotides, and other recognition molecules. Depending on the particle surface and biomolecule, conjugation can be performed through passive adsorption, covalent chemistry, affinity-based interactions, or other surface-functionalization strategies.
Gold nanoparticle conjugates are particularly well established in lateral flow assays and other point-of-care diagnostic formats. For reporter selection, conjugation options, and diagnostic products, see Nanoparticles for Precision Diagnostics.
Biomedical Research
Gold nanoparticles have been widely studied as platforms for biological imaging, biosensing, targeted delivery, and other biomedical applications. Their surfaces can be modified with proteins, peptides, polymers, and other molecules to control biological interactions or introduce targeting functionality.
Plasmonic gold structures such as gold nanorods and gold nanoshells can also absorb light and convert optical energy into heat. These properties have motivated extensive research into photothermal therapy and other light-responsive biomedical applications.
Plasmonics & Optical Engineering
Gold nanoparticles support localized surface plasmon resonances, where conduction electrons at the metal surface collectively oscillate in response to incident light. This interaction produces unusually strong absorption and scattering compared with similarly sized non-plasmonic particles.
Particle size and morphology determine how strongly absorption and scattering contribute to the optical response. Larger gold nanospheres can generate enough scattering for individual particles to be observed using dark-field microscopy, while anisotropic structures such as nanorods and nanoshells provide additional control over resonance wavelength.
These optical properties make gold nanoparticles useful for sensing, imaging, spectral filtering, and surface-enhanced spectroscopy techniques such as Surface-Enhanced Raman Spectroscopy (SERS). Learn more about gold nanoparticle optical properties or explore nanomaterials for optical engineering.
Why Choose nanoComposix Gold Nanoparticles?
Extensive Characterization Data
Gold nanoparticle products are supplied with batch-specific characterization data to help researchers understand the material they are using and compare performance over time. Depending on the particle platform, characterization may include transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential, UV-Visible spectroscopy, solution pH, and other relevant measurements.
Batch-specific Certificates of Analysis provide representative characterization data for the supplied material rather than relying only on nominal particle specifications.
Transparent Surface Chemistry & Formulation
Surface chemistry and suspension-buffer information are provided for nanoComposix gold nanoparticle products so researchers can account for these variables when designing experiments or integrating particles into downstream systems.
Surface options vary by particle platform and application and may include citrate, PEG-based coatings, carboxyl-functionalized surfaces, PVP, BPEI, dodecanethiol, silica-based coatings, and other chemistries. See the current gold nanoparticle portfolio for available combinations of particle size, morphology, surface chemistry, and formulation.
Flexible Concentration & Formulation Options
Gold nanoparticle concentration formats vary by particle platform and intended application. Products may be specified using mass concentration, optical density, or other application-relevant formats rather than a single concentration convention across the entire portfolio.
Higher-concentration formulations can be useful when downstream processing requires more particles in a smaller liquid volume, while lower-concentration dispersions may be convenient for characterization, optical studies, or direct experimental use. Always refer to the individual product page and Certificate of Analysis for the formulation supplied with a specific material.
Smaller gold nanoparticles generally remain well suspended under normal storage conditions. Larger particles may settle over time because of their greater mass but can typically be redispersed using the handling instructions provided for the material.
Colloidal Stability & Formulation Flexibility
Nanoparticle aggregation can significantly alter particle size, optical properties, surface accessibility, and downstream performance. nanoComposix gold nanoparticles are produced and processed as discrete particles with controlled size distributions and formulations designed to maintain colloidal stability.
Selected gold nanoparticle platforms are also available in dried, redispersible formats, and surface chemistry can be tailored to support dispersion in different solvents or compatibility with downstream materials. Learn more about gold colloids and dispersion stability.
Technical Support & Custom Development
Our nanoparticle scientists can help with particle selection, surface chemistry, formulation, characterization, and integration into downstream applications. If an off-the-shelf material does not meet your requirements, custom nanoparticle development can be used to evaluate alternative sizes, morphologies, optical properties, surfaces, and formulations.
Gold Nanoparticle Concentration & Optical Reference Data
The table below shows how particle size affects particle number concentration and optical response at two common gold mass concentrations. At a fixed gold mass concentration, larger particles result in fewer particles per mL and a different optical response.
| Size | 0.05 mg/mL | 1 mg/mL | Peak λ |
|---|---|---|---|
| 5 nm | 3.95 × 1013 particles/mL Peak OD: 0.80 |
7.91 × 1014 particles/mL Peak OD: 16.0 |
520 nm |
| 10 nm | 4.94 × 1012 particles/mL Peak OD: 0.82 |
9.88 × 1013 particles/mL Peak OD: 16.4 |
520 nm |
| 20 nm | 6.18 × 1011 particles/mL Peak OD: 0.85 |
1.24 × 1013 particles/mL Peak OD: 16.9 |
520 nm |
| 30 nm | 1.83 × 1011 particles/mL Peak OD: 1.1 |
3.66 × 1012 particles/mL Peak OD: 22.1 |
520 nm |
| 40 nm | 7.72 × 1010 particles/mL Peak OD: 1.1 |
1.54 × 1012 particles/mL Peak OD: 22.6 |
520 nm |
| 50 nm | 3.95 × 1010 particles/mL Peak OD: 1.5 |
7.90 × 1011 particles/mL Peak OD: 29.1 |
525 nm |
| 60 nm | 2.29 × 1010 particles/mL Peak OD: 1.6 |
4.58 × 1011 particles/mL Peak OD: 31.8 |
530 nm |
| 80 nm | 9.65 × 109 particles/mL Peak OD: 1.6 |
1.93 × 1011 particles/mL Peak OD: 31.5 |
545 nm |
| 100 nm | 4.94 × 109 particles/mL Peak OD: 1.0 |
9.88 × 1010 particles/mL Peak OD: 20.1 |
555 nm |
Reference concentrations: 0.05 mg/mL gold corresponds to 0.254 mmol/L Au and 0.005% gold by mass. 1 mg/mL corresponds to 5.08 mmol/L Au and 0.1% gold by mass.
Values are provided as technical reference data rather than a list of currently stocked product configurations. Actual optical properties depend on particle size distribution, morphology, surface chemistry, and surrounding medium. Refer to the individual product page and batch-specific Certificate of Analysis for current configurations and measured values.
For more detail on how particle size, concentration, and colloidal formulation relate to gold nanoparticle behavior, see Gold Colloids. For the underlying size- and shape-dependent properties, continue to Gold Nanoparticle Physical Properties and Gold Nanoparticle Optical Properties.
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