LI SILVER™ is a convenient, light-insensitive silver enhancement system for use with NANOGOLD® reagents, which may be used for EM or light microscopy or to visualize NANOGOLD® on blots. LI SILVER consists of 125 mL ready-to-use enhancer and 125 mL ready-to-use initiator; the reagent is formed by combining equal volumes of these solutions. The mixture is usable only for a defined time period, as given below, and should therefore be prepared immediately before use. LI SILVER is nucleated quickly by NANOGOLD® particles, resulting in the precipitation of metallic silver and the formation of a dark brown to black signal. The system has markedly delayed self-nucleation resulting in high contrast and very low background and non-specific staining.
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 an 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 45 minutes; at 20°C, the solution is stable for at least 40 minutes, and at 24°C for at least 35 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 enhancer and initiator solutions at 2 - 8°C. DO NOT FREEZE. Do not expose to extreme heat or light. Avoid contact with metallic objects, since these can induce silver precipitation. Avoid cross-contamination of the enhancer and initiator solutions. Avoid skin contact: the silver enhancement reagents will stain skin.
Samples must be rinsed with deionized water before silver enhancement. This is because the reagent contains silver ions in solution, which react to form a precipitate with chloride, phosphate and other anions which are components of buffer solutions.
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. Non radioactive and non carcinogenic.
Note: All LI SILVER™ solutions should be equilibrated to room temperature prior to the enhancement procedure.
