40 nm Gold Nanospheres with Streptavidin

Product Number


  • All BioReady products are specially formulated for lateral flow and biodiagnostics
  • Mean diameter: 40 ± 4 nm
  • Size distribution (CV) < 15%
  • Available at 10 OD and is provided in DI water
  • Looking for greater sensitivity?

Certificate of Analysis Examples

Please note that these are representative Certificates of Analyses (CoAs) provided as examples for this product. We provide a unique batch-specific CoA with each product during shipment; only the CoA that arrives with your product should be referred to for actual characterization and measurement data. If you would like an electronic copy of the CoA for the product you received or the material(s) we currently have in stock, please contact us.

Product Line Surface Example Certificate of Analysis Product # Price
BioReady Streptavidin, 10 OD Download ↓ AUIR40-200U €145+
BioReady Streptavidin, 10 OD Download ↓ AUIR40-1M €455+
BioReady Streptavidin, 10 OD Download ↓ AUIR40-5M €1,835+
BioReady Streptavidin, 10 OD Download ↓ AUIR40-10M €3,100+

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Gold Nanoparticle Applications

Diagnostic Applications

Gold nanopaticles are readily conjugated to antibodies and other proteins due to the affinity of sulfhydyl (-SH) groups for the gold surface, and gold-biomolecule conjugates have been widely incorporated into diagnostic applications, where their bright red color is used in home and point-of-care tests such as lateral flow assays.  

Biomedical Applications

Gold nanomaterials can be conjugated to biomolecules to specifically target cancer cells, and used for photothermal cancer therapy, where their tunable optical properties cause them to convert laser light into heat and selectively kill cancerous cells.   


Gold nanoparticles have unique optical properties because they support surface plasmons. At specific wavelengths of light the surface plasmons are driven into resonance and strongly absorb or scatter incident light. This effect is so strong that it allows for individual nanoparticles as small as 30 nm in diameter to be imaged using a conventional dark field microscope.  This strong coupling of metal nanostructures with light is the basis for the new field of plasmonics.  Applications of plasmonic gold nanoparticles include biomedical labels, sensors, and detectors. The gold plasmon resonance is also the basis for enhanced spectroscopy techniques such as Surface Enhanced Raman Spectroscopy (SERS) and Surface Enhanced Fluoressence Spectroscopy which can be used to detect analytes with ultrahigh sensitivity. 

Ultra Uniform Gold Nanospheres

Our standard Au nanospheres have a variety of useful surface chemistries and narrow size distributions (CV < 15%), appropriate for a variety of applications ranging from lateral flow assays to optical coatings. Some applications, however, such as multiplexed dark field labeling or standards for nanoparticle size and shape, require even tighter tolerances on shape and size dispersity. For these applications, nanoComposix has successfully manufactured ultra-uniform, monodisperse gold nanospheres with sizes tunable from 10 nm up to 200 nm. As shown below, these gold nanoparticles have a nearly perfect spherical shape, smooth surfaces, and impressively narrow size distributions (CV < 6%, and for many sizes CV < 4%).

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Optical and Scattering Properties

Due to their high uniformity in size and shape, these Au nanospheres scatter a single color of light under dark field microscope imaging (shown below). The high purity of their light scattering signatures makes these nanospheres perfect scattering labels for imaging and building blocks for plasmonic nanostructures and devices.

Surface Chemistry

The gold nanospheres are stabilized with citrate in an aqueous solution. With their stable, easily displaceable surface chemistry, the gold nanospheres can be readily functionalized with a wide variety of molecules, including polymers and small molecules with desired functional groups, inorganic coatings such as silica, and biomolecules including DNA and antibodies for your application.

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Need Greater Sensitivity?

Gold nanoshells typically provide 2–20× increases in lateral flow diagnostic assay sensitivity versus 40 nm gold nanoshells. The gold nanoshells consist of a 120 nm silica core that is coated with a 15 nm gold shell. The nanoshells are less dense than solid 150 nm gold spheres and are highly uniform resulting in excellent flow characteristics. Since the particles have the same gold surface as 40 nm gold nanospheres, only minor changes to conjugation protocols are required in order to generate ultrasensitive assays. The price per OD-mL of the nanoshells is only slightly higher than our 40 nm gold nanoparticles.

For more information about increasing your assay sensitivity with gold nanoshells, see our BioReady Gold nanoshell page.