We can label almost ANY molecule!

Our precision Nanogold® labels are attached by covalent cross-linking, so they may be used to label almost any molecule with a suitably reactive functionality. We have successfully conjugated our probes to proteins, lectins, peptides, lipids, biotin and cytoskeletally active probes such as modified phalloidins, and of course antibody probes of all kinds.

Helpful info for us about your project:

• Molecular structure and functional groups: Ideally, targeted biomolecules should be labeled at a unique reactive group, remote from the substrate binding region, and we try to identify suitable sites for labeling, such as a unique thiol or a terminal primary amine. Some idea of the overall structure of your molecule and which regions are thought to bind to the target would be very helpful in selecting a labeling site. Thiols, primary amines, carboxylates and aldehydes may all be readily labeled. Labeling through hydroxyls or cis-1,2-dihydroxy groups are also good candidates. Other groups are also possible, but may require more extensive work to achieve.
• Data on properties such as solubility and compatibility with various solvents is also useful, because small molecules can sometimes alter the solubility properties of gold clusters significantly. Knowing an alternative solvent beforehand saves time spent solubility testing later.
• References for labeling with other tags: We can often obtain a good idea about which labeling approaches might work from related literature articles. A paper which describes a successful labeling with a fluorophore, for example, is a good starting point for evaluating potential gold-labeling strategies, because our gold labels are conjugated using similar cross-linking reactions and have similar site requirements.
• Molecular weight: All our labeling reactions use specific molar ratios of gold to probe. We need the molecular weight to calculate how much gold labeling reagent we will need, how much of the probe we will need to use for labeling, and also which product isolation protocol to use.
• Optical density or UV/visible absorption data: The extinction coefficients of Nanogold® and FluoroNanogold at specific wavelengths have been accurately determined, and these values allow us to determine how successfully your probe has been labeled. If you supply or refer us to specific values for your probe, we can provide you with the exact ratio of gold cluster label to probe in the product.