IVD-READY Gold Nanoparticles for Lateral Flow Assays and Biosensing

representation of IVD-READY gold nanoparticles collection of NanoBrand

Gold Nanoparticles Prepared for Lateral Flow and IVD Assays

IVD-READY gold nanoparticles are spherical, monodisperse gold nanoparticles (AuNPs) prepared for conjugation to antibodies, proteins and nucleic acids in lateral flow assays and other in vitro diagnostic (IVD) formats. NanoBrand offers them in 20, 40, 80 and 100 nm with a citrate or PEG5000-carboxylate surface, at optical density 20 or 50, dispersed in water free of buffers and reactants, and characterized lot by lot.

IVD-READY designates the NanoBrand gold nanoparticles that meet the criteria for in vitro diagnostic assay work: a narrow size distribution, with low coefficient of variation and low polydispersity index, a well-defined size and spherical shape, a formulation free of reactants, and a controlled surface chemistry for stable, reproducible conjugation. Read more on Increasing Accuracy and Specificity in Biosensing.

The line is designed for developers of lateral flow assays and rapid diagnostic tests, ELISA and colorimetric immunoassays, microfluidic and lab-on-chip systems, protein detection, nucleic acid detection and optical or plasmonic biosensor platforms.

Which Size for Your Lateral Flow Assay

In a lateral flow assay, smaller gold nanoparticles generally migrate faster and more uniformly through the membrane and are less prone to steric crowding at the test line. Larger particles scatter more light and can produce a stronger visible signal at the same particle concentration. The final particle-size choice should be confirmed using the complete conjugate and membrane system, not the bare nanoparticles alone.

Property Smaller IVD-READY sizes (20nm, 40nm) Larger IVD-READY sizes (80nm, 100 nm)
Color Cherry red Wine to violet
Brightness per particle Lower Substantially higher, stronger optical scattering
Migration through the membrane Faster and more uniform Slower
Colloidal stability Easier to maintain Requires more careful handling
Antibody needed per particle Less More
Access to crowded surfaces Better Reduced by sterric hindrance
Best suited to Abundant targets, competitive formats, crowded surfaces Low-abundance targets, maximum line intensity

Testing several sizes under identical assay conditions helps identify the nanoparticle that provides the best balance of visual signal, sensitivity, conjugate stability, membrane flow, and assay specificity. IVD‑READY Size Optimization Kit enables rapid comparison of nanoparticle diameter in lateral-flow assays, colorimetric biosensors, immunoassays, and other diagnostic formats.

For broader research and development needs, NanoBrand offers Citrate-coated Gold Nanoparticles in 16 sizes from 5 to 200 nm, providing a versatile, general-purpose surface for bioconjugation and other applications. Our Gold Nanostars support SERS, plasmonic sensing, and photothermal research. For additional context, see our overview of Biocompatible Nano-gold for Therapeutic and Diagnostic Applications. 

Available IVD-READY Spherical Gold Nanoparticle Products:

representation of citrate-coated and PEG5000-coated gold nanoparticles

Citrate or PEG5000-carboxylate Surface

NanoBrand IVD-READY gold nanoparticles are available with either a citrate-stabilized or PEG5000-carboxylate surface, providing flexible options for antibody conjugation, protein conjugation, oligonucleotide coupling, and diagnostic assay development.

On citrate-stabilized AuNPs, proteins, antibodies, and other biomolecules can bind through passive adsorption, while thiol-containing ligands form strong gold–sulfur (Au–S) bonds. This surface is well suited to rapid conjugation screening, passive adsorption-based workflows, and early-stage lateral flow assay optimization.

On PEG5000-carboxylate gold nanoparticles, activation of surface carboxyl groups with EDC/NHS enables covalent coupling to biomolecules with free primary amines. This surface is particularly suitable for covalent antibody conjugation, protein coupling, and oligonucleotide immobilization when targeting specificity, conjugate stability, and reliable performance in complex sample matrices are important.

Both surface chemistries are designed to support colloidal stability, low background, reproducible conjugation, and lot-to-lot consistency for IVD, lateral flow, biosensing, and other diagnostic applications. Custom surface coatings are available on request.

Monodispersity,  Purity and the Certificate of Analysis (CoA)

Each IVD-READY gold nanoparticles lot is supplied with a detailed, lot-specific Certificate of Analysis (CoA) and Safety Data Sheet (SDS). The CoA includes TEM images, particle-size distribution, UV-Vis spectrum, hydrodynamic diameter, Zeta potential, and key quality-control metrics to support confident evaluation of nanoparticle quality and assay suitability.

Monodisperse gold nanoparticles provide a more uniform optical response and predictable surface behavior. A reactant-free dispersion helps minimize background interference and non-specific binding during antibody conjugation, lateral flow assay development, biosensing, and other IVD workflows.

Tight lot-to-lot consistency supports stable signal intensity, sensitivity, and quantitative assay performance across development, validation, and production runs. The IVD-Ready CoA includes the documentation needed to support method validation and lot qualification from feasibility studies through scale-up.

To learn how nanoparticle properties can influence assay performance, read When Your Biosensor Fails, Is It the Biology or Your Nanoparticles?   NanoBrand also offers Nanoparticle Characterization Services for customer samples, including TEM, DLS, zeta potential, UV-Vis, ICP-MS and related analyses. Explore peer-reviewed scientific articles to see applications of NanoBrand gold nanoparticles in diagnostics, biosensing, and related research.

picture of three bottles containing NanoBrand gold nanoparticles of different diameters

Configurations, pricing and ordering

Each IVD-READY gold nanoparticle size is available at optical density OD 20 and OD 50, offering concentrated formats  for biosensing, lateral flow assay development, and other IVD applications. A size-optimization kit combines the 20, 40, 80, and 100 nm particles for convenient side-by-side comparison during assay development.

Pricing depends on gold nanoparticle size, surface chemistry, optical density, and order volume. The price for each selected configuration is displayed on the relevant product page and updates automatically in the shopping cart.

  • Universities: 10% discount applicable to the purchase order
  • Returning customers: 5% discount added to the cart automatically
  • Products are manufactured in Canada and ship in 1–2 weeks for small orders and 2–3 weeks for large orders 
  • Custom diameters and surface chemistries: please send us the diameter, surface coating, concentration as OD or particles per ml, and order volume
  • Bulk quantities: lead times are confirmed following review of the requested specifications, concentration, batch volume and characterization requirements

Frequently Asked Questions

What is the difference between the citrate line and IVD-READY gold nanoparticles?

Both NanoBrand product lines provide high-quality gold nanoparticles with the same level of core characterization, but they are designed for different development and application needs.

IVD-READY gold nanoparticles are designed for conjugation and diagnostic assay development, including lateral flow assays, rapid tests, and biosensor platforms. They are available in 20, 40, 80, and 100 nm sizes at OD 20 or OD 50, with either a citrate surface for passive adsorption or a PEG5000-carboxylate surface for covalent EDC/NHS coupling to biomolecules with primary amines. Each lot is supplied with a lot-specific Certificate of Analysis (CoA) that includes defined validation ranges for key characterization variables, helping simplify method validation, lot qualification, and documentation from feasibility through verification, validation, and scale-up. See an example CoA for 40 nm IVD-READY citrate-coated gold nanoparticles.

Citrate-coated gold nanoparticles are NanoBrand’s general-purpose AuNPs for research, bioconjugation, early assay development, passive adsorption, thiol–gold binding, and applications requiring further surface modification. They are available in 16 sizes from 5 to 200 nm, offering broad flexibility when particle-size selection is important. Each lot is supplied with a lot-specific CoA containing the relevant technical characterization data. See an example CoA for 40 nm citrate-coated gold nanoparticles.

Which gold nanoparticle size works best for a lateral flow assay?

There is no single best gold nanoparticle size for every lateral flow assay. Smaller particles generally migrate faster and more uniformly through the membrane, while larger particles can provide a stronger visible signal at the test line. The optimal balance depends on the conjugate, membrane, assay format, and target performance.

The size optimization kit includes 20, 40, 80, and 100 nm gold nanoparticles, allowing all four sizes to be conjugated and tested side by side on the same lateral flow strip before selecting the most suitable size.

Should I use passive adsorption or covalent coupling for a lateral flow conjugate?

The best conjugation method depends on the antibody or biomolecule, assay format, and sample matrix.

Passive adsorption on citrate-coated gold nanoparticles is a simple, fast approach that does not require activation chemistry. It is often well suited for initial conjugation screening and lateral flow assays where the conjugate performs reliably under the intended test conditions.

Covalent coupling on PEG5000-carboxylate gold nanoparticles requires activation of the surface carboxyl groups, typically using EDC/NHS chemistry. It forms covalent bonds with biomolecules containing free primary amines, which can provide stronger conjugate attachment and improved stability, especially in complex sample matrices.

Both citrate and PEG5000-carboxylate surface options are available in the NanoBrand IVD-Ready line, allowing the conjugation route to be matched to the requirements of each lateral flow assay.

Is colloidal gold the same thing as gold nanoparticles for lateral flow?

Yes. Colloidal gold is the traditional term for gold nanoparticles dispersed in a liquid. In lateral flow assays, it generally refers to the spherical gold nanoparticles used as visible labels for antibodies, proteins, or other detection molecules.

NanoBrand IVD-Ready gold nanoparticles are colloidal gold supplied with a defined particle size, controlled surface chemistry for conjugation, and a lot-specific Certificate of Analysis. Their citrate or PEG5000-carboxylate surfaces support passive adsorption or covalent coupling, depending on the assay design.

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