80 nm Bare Gold Nanospheres for Passive Adsorption

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Which Surface Should I Choose?

Surface Binding type Pros Cons
Carbonate Learn more + Passive adsorption
(aka physisorption)
  • Simple conjugation method (mix and wait)
  • Low cost
  • Less stable in various pH/buffer conditions than covalent bonding
  • Requires more antibody per particle

BioReady carbonate gold nanoparticles have a “naked” particle surface with only a weakly bound carbonate molecule stabilizing the particle. Similar to citrate-stabilized gold, the carbonate is readily displaced in the presence of proteins for passive adsorption (also referred to as physisorption). The mechanism of adsorption is based on Van der Waals interactions between the proteins (e.g. antibodies) and the surface of the particles. The resulting forces between the antibody and the nanoparticle are influenced by the coupling environment. BioReady carbonate gold is provided at an optical density (OD) of 4 at pH ~8.0–8.5, which is optimal for conjugation to many IgG antibodies. A pH titration can be performed to optimize the pH of conjugation.

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 CoA Product # Price
BioReady Bare (Carbonate), 5 OD Download Example ↓ AUKR80-50M €210+
BioReady Bare (Carbonate), 5 OD Download Example ↓ AUKR80-100M €380+
BioReady Bare (Carbonate), 5 OD Download Example ↓ AUKR80-500M €1,725+

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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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