R-Gent SE-EM Silver Enhancement Reagents

Electron Microscopy:

For most applications the detection of ultra small gold particles in electron microscopy requires a particle enhancement procedure. Danscher’s method has always been the standard for this purpose and for a long time attempts to improve the features of Danscher’s system met with only limited success.

The goal in the development of AURION R-Gent SE-EM was to create a new system with enhancement efficiency and homogeneity at least comparable to Danscher’s method, but with reduced acidity and light sensitivity. In addition, the reagents should have low viscosity for the suitability in pre-embedding immunogold labeling

The silver enhancement reaction is a gold particle-catalysed reduction in which silver ions are reduced to metallic silver with a photographic developing compound as the electron source. In addition in many applications a “protective colloid” is added to the enhancement solution to limit diffusion of reagents to the gold particle surface, thus providing a means for controlling particle growth.

Light Microscopy:

The Immunogold Silver Staining technique (IGSS) finds application in both fields of electron microscopy and light microscopy. In addition, the technique is used to identify proteins or nucleic acids in different immunoassays, for example, immunoblotting.

Light microscopical and macroscopical visualisation of the latent gold signal requires an enhancement system that renders a high contrast signal. Light insensitivity and negligible autonucleation are required for ease of handling and low background. AURION R-Gent SE-Intense is a two-component reagent optimized to meet with these requirements.

Aurion R-Gent Intense is the successor of R-Gent SE-LM.

The silver enhancement reaction is based on the gold particle catalyzed reduction of Ag+ to metallic silver using photographic developing compounds as the electron source. For light microscopy and immunoblotting applications the generated silver signal should be of high contrast. Furthermore the signal should be permanent and compatible with counterstaining.

Aurion R-Gent SE-Intense is the successor of Aurion R-Gent SE-LM. Key aims during the development of this new product were: contrast, reaction speed and reproducibility.

Enhancement Conditioning Solution:

Incubation buffers suited for immuno gold labelling commonly contain ions such as phosphate and chloride which are not compatible with silver ions causing precipitation of insoluble silver salts. These ions therefore need to be thoroughly removed before enhancement. Whereas pure water is suited to fulfil this requirement in the purely chemical sense, it is rarely the best way when working with delicate specimens potentially affecting ultrastructural details vulnerable to drastic changes in ionic concentration. Using water it is also necessary to carefully blot the specimens and remove the water without drying before applying Aurion R-Gent SE-EM. Failing to do so will result in dilution and diminished activity of the silver enhancement reagents, especially when working with small volumes.
Aurion developed Aurion ECS to negotiate optimum conditions for enhancement while at the same time avoiding the risks posed by water. Its ionic strength is similar to immuno incubation buffers and its make up is compatible both with these buffers as well as with Aurion R-Gent SE-EM.
Aurion ECS is therefore highly recommended for single labelling experiments. It is an absolute requirement for double labelling where ECS not only reconditions specimens for the next immuno steps but also avoids the use of aldehyde fixation after the first immuno gold silver labelling sequence.