12 nm Maleimido Nanogold® is a highly monodisperse, highly water-soluble, stable, and biocompatible 12 nm gold nanoparticle, with a hydrophilic coating, modified with maleimide groups that react with thiols (sulfhydryls) under mild conditions (pH 6.0 to 7.0).
Use our unique Nanogold® labeling reagents just as you would use fluorescent labeling reagents.
Labeling with 12 nm Maleimido Nanogold®, like the smaller 5 nm Maleimido Nanogold®, is straightforward: Simply mix reconstituted 12 nm Maleimido Nanogold® with the target molecule for one hour at room temperature or 16 h in the refrigerator.
Once reaction is complete, labeled proteins may be isolated by ammonium sulfate precipitation, and oligonucleotides by ethanol precipitation or gel electrophoresis. Alternatively, conjugates may be chromatographically separated by gel filtration; ion exchange chromatography or hydrophobic interaction chromatography may also be useful.
The maleimide group specifically reacts with a thiol under mild conditions to produce a stable, covalent thioether bond.
Schematic showing reaction of 12 nm Maleimido Nanogold® with a thiol-functionalized molecule.
Selectively label any molecule with an accessible thiol group!
- Antibody IgG and IgM: label at a hinge thiol, remote from the binding site – preserve affinity.
- Antibody Fab’ fragments: attach the 5 nm Nanogold® at the hinge thiol at the opposite end to the binding site – preserve maximum native binding affinity.
- Proteins and peptides: Label selectively at a unique thiol site, or incorporate a unique Cys residue during peptide synthesis at the site you wish to label.
- DNA, RNA and PNA: Use a thiol-modified phosphoramidite or cysteine during synthesis to put a thiol right where you want the gold – or modify enzymatically in situ to place the gold at the modification site.
- Nanostructured materials: label a building block, then assemble for a programmed gold nanoparticle array, or program specific labeling sites into a nanostructure and add the gold afterwards.
- Small molecules: Decorate 12 nm Nanogold® with small molecules such as hormones, inhibitors, or signalling molecules, then localize binding sites with molecular precision.*
12 nm Nanogold® Labeling Reagents
Precise, permanent Nanogold® labeling reagents – Now in a larger size!
12 nm Nanogold® brings the power and versatility of Nanogold® in a even larger and more readily visualized 12 nm size. Like our smaller 5 nm and 1.4 nm Nanogold® reagents, it covalently reacts at specific sites under mild buffer conditions to give a well-defined product that may be purified chromatographically or by ammonium sulfate precipitation.
Unlike conventional colloidal gold, 12 nm Nanogold® does not require any additional macromolecules for stabilization. Conjugate probes are often smaller than colloidal gold probes and can achieve higher resolution because they can be prepares using smaller targeting agents, giving more precise and more nearly quantitative labeling.
Make any molecule a gold probe!
Unconjugated 12 nm Nanogold®, showing monodisperse, highly regular, spherically symmetrical 12 nm gold core and uniform, consistent ligand coating. This ensures a highly regular particle size and reliable, reproducible labeling and EM results.
Nanogold® brings the versatility of fluorescent conjugation to gold labeling.
Now you have a choice of sizes for Nanogold®: 1.4, 5 or 12 nm, enabling multiple labeling for electron microscopy without silver or gold enhancement!
- Antibodies
- Proteins
- Peptides
- Oligonucleotides and nucleosides: DNA, RNA and PNA
- Nanostructured materials
- Hormones
- Polymers
- Surfaces
Features and Advantages
- Stable, soluble and biocompatible. Designer coating gives solubility and biocompatibility so conjugates and probes may be used in vivo.
- Low background. No residual charge: minimal non-specific binding.
- Highly monodisperse. Size variation less than 10% for 12 nm. 1.4, 5 and 12 nm Nanogold enable double or even triple labeling with non-overlapping sizes
- Molecular precision. Use smaller targeting agents to make smaller primary probes that get the gold closer to the target.
- Site-specific conjugation enables programmed incorporation into nanostructured materials or components of self-assembling systems.
- No need for additional proteins or polymers: preparation is straightforward with no need for salt titration.
- Pick the optimum size: smaller for high resolution, molecular labeling, larger for visualization on a cellular scale.
- Easily enhanced. Enlarge with silver or gold enhancement and retain higher monodispersity – or achieve super-sensitive detection for blots and optical detection systems. If larger particle sizes are needed, 12 nm Nanogold® may easily be enhanced with:
Depending on the reagents used, a brief exposure (1 – 4 minutes) produces highly visible grains 20-30 nm in size for wide-field electron microscope visualization, while longer development times produce black signals, readily differentiated from organic chromogens, that are easily seen in the light microscope and on immunoblots, gels and Western blots.