In order for a gold probe to produce a strong specific signal together with a low background the conjugation of antibody to gold particle must be complete and stable under a variety of incubating conditions. The gold particle must have the minimum effect on the activity of the antibody to which it is conjugated but be strongly enough absorbed to the surface to remain stable for years. For long term storage it should be possible to freeze a gold conjugate without loss of the antibody activity. SPI- Mark gold conjugates may be frozen and stored over long time intervals without deterioration. Clustering For electron microscopy a very low level of clustering is important, especially if quantitation is to be performed or high quality micrographs are required.
Clustering indicates a poor absorption of protein with bridging between gold particles.
Heavily clustered conjugates have low stability and poor sensitivity. All SPI-Mark EM Grade gold conjugates are made to this high specification. The strict quality assurance procedures used at all stages during the manufacture of SPI-Mark gold reagents ensure that all of these criteria are fully met and that our products have the highest possible specification and performance. Inc. Contacting Structure Probe, Inc . All rights reserved.