Biocompatible Gold Nanoparticles │ AuNPs

Q: Which surface chemistry should I use for in vivo applications?

For in vivo applications, surface chemistry should be selected for the administration route, target tissue, and intended function. The surface influences protein adsorption, circulation time, biodistribution, cellular uptake, and clearance, so there is no universal coating suitable for every formulation. PEG-based coatings are commonly used to improve colloidal stability and reduce nonspecific protein adsorption, supporting longer circulation. Zwitterionic ligands are another option when minimizing protein adsorption is especially important. Targeting ligands can direct particles toward a specific cell type or tissue, while dyes or contrast labels support imaging and positively charged ligands can complex nucleic acids. All in vivo formulations require application-specific testing for safety, distribution, and performance. Citrate is a practical starting surface because it forms during aqueous AuNP synthesis and can be exchanged with more strongly binding thiolated ligands. Beginning with particles free of residual surfactant is important: residual surface-active materials can affect biological performance and can interfere with controlled replacement by the intended ligand shell.

Biocompatible Gold Nanoparticles AuNPs for Therapeutics and Diagnostics

Biocompatible gold nanoparticles (AuNPs) are nanoscale gold particles manufactured so that synthesis carryover does not interfere with biological systems: no residual reactants, no stabilizing agents, base-metal impurities below detection limits, and defined surface chemistry. This level of cleanliness sets the starting point for any medical application. NanoBrand manufactures AuNPs to this standard, with lot-specific characterization.

What makes a Gold Nanoparticle biocompatible?

Biocompatibility is set less by the gold than by what is left on it after synthesis and by how uniform the batch is. The table lists the parameters NanoBrand controls on every lot, why each one matters, and the value supplied.

Parameter	Why it matters	NanoBrand
Residues from synthesis	Surfactants, buffers and leftover reactants are foreign materials at the particle surface	Free of reactants, buffers, proprietary stabilizing and dispersing agents, sodium azide, PBS, Tweens, BSA, glycerol, CTAB and CTAC residues.
Surface	The surface is what proteins and cells meet first, and what a ligand attaches to	True citrate surface formed during synthesis, no CTAB replacement. Custom surface chemistry available
Metal purity	Base metal impurities travel with the gold into the biological system	Gold precursors produced and purified in-house. Base metal impurities controlled by ICP-MS and kept below detection limits
Size uniformity	Mass per particle scales with diameter, so a wide distribution is an undefined dose	Coefficient of variation CoV under 5 % of target diameter for 10 to 200 nm nanoparticles. Polydispersity index under 0.100
Lot-to-lot reproducibility	Results obtained on one lot must transfer to the next ones	Lot-specific characterization supplied with every order. Minimal variations between orders due to high monodispersity and quality control.
Manufacturing	Process control ensures that the specifications are consistently met for every lot	Following Good Manufacturing Practices guidelines, ISO applications ongoing. Manufactured in Canada

Applications

Drug Delivery

Gold nanoparticles (AuNPs) are being studied as drug-delivery nanocarriers for poorly soluble anti-cancer drugs, proteins, vaccines, and nucleic acids. A single functionalized AuNP can be engineered to carry multiple therapeutic payloads, targeting ligands, and responsive components. By tuning particle size, surface chemistry, and bioconjugation strategy, researchers investigate AuNP platforms for high drug loading, prolonged circulation, targeted delivery to tissues such as tumours, and controlled drug release. NanoBrand supports gold nanoparticle design and surface functionalization for targeted drug-delivery and controlled-release research.

Read more: Gold nanoparticles for Drug Delivery
Biosensing, Lateral Flow Assays and Personalized Medicine

In biosensing, AuNPs detect disease biomarkers, bacteria, viruses, antibodies, drugs, and environmental pollutants. Surface, swab, and biological-fluid testing for bacteria and viruses remains one of their best-known applications. NanoBrand’s ultra-monodisperse particles are designed for this work and can support development of your specific biosensing application, from assay design to particle selection. Because test sensitivity, reproducibility, and signal regularity depend on particle uniformity, monodispersity is a key specification. Consistent particle size can also support more reliable assay optimization, validation, and comparison across test batches.
Read more: Gold nanoparticles for Biosensing
Gene Therapy

Gold nanoparticles (AuNPs) are being investigated as versatile non-viral vectors for gene delivery and gene silencing. Their readily functionalized surfaces, high surface-area-to-volume ratio, and tunable optical properties support research into nucleic-acid loading, delivery, tracking, and light-triggered functions. Gold nanoparticles can be engineered to carry DNA, mRNA, siRNA, miRNA, and targeting ligands through multivalent surface attachment. For gene-delivery research, NanoBrand can prepare AuNPs with a positively charged surface stabilizer selected for your application, enabling electrostatic binding of nucleic acids.

Read more: Gold nanoparticles for Gene Therapy
Photothermal Therapy

NanoBrand offers gold nanoparticle products with absorbance peaks from 700 to 1000 nm, within the near-infrared range widely used for photothermal research, and can engineer particles for the wavelength required by your application. AuNPs absorb near-infrared light and convert it into localized heat through plasmonic photothermal effects. In photothermal therapy research, particles are designed to accumulate at a tumour and are then irradiated, concentrating heat near the particles rather than uniformly throughout surrounding tissue. AuNP surfaces can also carry therapeutic cargo, supporting combined photothermal drug-delivery approaches and light-responsive release strategies. Imaging-capable particles may further support image-guided treatment and monitoring in preclinical research platforms.
Medical Imaging

Gold attenuates X-rays more strongly than iodine, and AuNPs are studied as CT contrast agents that may provide high contrast at lower dose and remain in circulation longer. Beyond CT, AuNPs can support MRI, optical imaging, photoacoustic imaging, SERS, and emission tomography when combined with appropriate contrast components, radionuclide labels, fluorescent dyes, or magnetic materials. Their tunable optical properties and functionalizable surfaces make them useful research platforms for targeted and image-guided imaging approaches. NanoBrand can tune particle optical properties, develop stabilizing surface coatings, and functionalize particles with fluorescent dyes or other application-relevant labels for your imaging modality.
Theranostics

Theranostics combines diagnosis, treatment, and response monitoring within a single platform. AuNPs are promising building blocks for cancer and other disease applications because their surfaces can integrate targeting ligands, imaging agents, therapeutic cargo, and responsive components within one multifunctional particle design. These multifunctional AuNPs-based theranostic systems are of particular interest in personalized-medicine research, where diagnosis and treatment may be adapted to disease characteristics and treatment response. NanoBrand can support the design of multifunctional gold nanoparticles with the size, surface chemistry, and configuration required for a specific theranostic research platform.

Explore peer-reviewed scientific articles featuring our Gold Nanoparticles and discover how they have been applied in published studies.

Frequently Asked Questions

Are gold nanoparticles biocompatible?

Metallic gold is chemically inert, and gold nanoparticles are among the most widely studied nanomaterials for biological applications. In practice, biocompatibility depends less on the gold core than on residual synthesis materials, particle size and shape, dose, aggregation state, and the surface chemistry used for the intended application.

A particle manufactured with minimal residual reactants and a well-defined surface provides a cleaner starting point for formulation. However, suitability for any specific biological, diagnostic, or medical use must be established through application-specific testing by the formulator.

Which surface chemistry should I use for in-vivo applications?

For in-vivo applications, surface chemistry should be selected for the administration route, target tissue, and intended function. The surface influences protein adsorption, circulation time, biodistribution, cellular uptake, and clearance, so there is no universal coating suitable for every formulation.

PEG-based coatings are commonly used to improve colloidal stability and reduce nonspecific protein adsorption, supporting longer circulation. Zwitterionic ligands are another option when minimizing protein adsorption is especially important.

Targeting ligands can direct particles toward a specific cell type or tissue, while dyes or contrast labels support imaging and positively charged ligands can complex nucleic acids. All in vivo formulations require application-specific testing for safety, distribution, and performance.

Citrate is a practical starting surface because it forms during aqueous AuNP synthesis and can be exchanged with more strongly binding thiolated ligands. Beginning with particles free of residual surfactant is important: residual surface-active materials can affect biological performance and can interfere with controlled replacement by the intended ligand shell.

Any formulation intended for in vivo use must undergo application-specific testing to evaluate its safety, distribution, and performance.

Is theragnostics the same as theranostics?

Yes. Both terms describe a single agent that combines diagnostic and therapeutic functions, for example a gold nanoparticle that carries an imaging label and a drug, or that is used both to locate a tumour and to heat it. Theranostics is the more common spelling in the literature (and is the form used on this site).; theragnostics is also in use.

Discuss your application

Representation of a gold nanoparticle AuNP

Tell us the application, the surface chemistry you need and the size range you are working in, and we will propose a particle and a quotation. If the specification is not yet defined, our R&D team can develop it with you.

Discuss your application Discover Gold Nanoparticles