HQ SILVER™ is a high-quality silver enhancement system for use with NANOGOLD® reagents, and is specially formulated for EM or light microscopy. HQ SILVER™ includes a protective colloid, which delays self-nucleation, reduces background staining and ensures uniform results with high signal-to noise ratio;1,2 neutral pH assures excllent structural preservation. The system consists of 15 ml initiator, 15 ml moderator, and 15 ml activator; the reagent is formed by combining equal volumes of the moderator, initiator, and then the activator solutions. The mixture is usable only for a defined time period, as given below, and should therefore be prepared immediately before use. HQ SILVER™ is nucleated by NANOGOLD® particles, resulting in the precipitation of metallic silver and the formation of a black signal.
Silver enhancement is time-dependent: for the first time period the reaction is highly specific for gold particles. NANOGOLD® particles will nucleate the deposition of dense silver particles which will enlarge rapidly in this period. The rate of growth of these particles will decline with time as their surface area increases. The enhancement time is the time required to obtain a adequate amplification of the NANOGOLD® signal without background staining. After a certain time beyond the enhancement time, silver may be precipitated spontaneously by self-nucleation, producing background signal.
This time period varies with temperature. At 16°C the developer solution is stable (no self-nucleation occurs) for at least 20 minutes; at 20°C, the solution is stable for at least 15 minutes, and at 24°C for at least 10 minutes. After this time, background staining may be observed. For applications where a very high degree of enhancement is to be combined with low background staining, enhancement may be repeated with a fresh portion of the enhancement mixture: development will continue but self-nucleation will be very low since the self-nucleation process restarts with each freshly mixed portion of developer.
Store the component solutions at -20°C; thaw and allow to equilibrate to room temperature before use. The solutions are lightsensitive! Silver enhancement must be carried out in a darkroom or light-tight box. A safelight or other darkroom light may be used. Do not expose to heat. Avoid contact with metallic objects, since these can induce silver precipitation. Avoid cross-contamination of the enhancer and initiator solutions: to prevent replacing the caps on the wrong bottles, the cap of the initiator (solution A) is red, while that of the activator (solution C) is blue. Avoid skin contact: the silver enhancement reagents will stain skin.
Warning: For research use only. Not recommended or intended for diagnosis of disease in humans or animals. Do not use internally or externally in humans or animals.
