title: Problems in the production and use of 5 nm avidin-gold colloids.
abstract: Over the past 5 years we have encountered several problems in the production and use of 5 nm avidin-gold colloids for markers in electron microscopy. These problems include flocculation of colloids during reduction of chloroauric acid, insoluble gold pellets following ultracentrifugation, and non-specific binding of avidin-gold colloids to biological membranes. We are able to avoid these problems by: avoiding the use of crystalline chloroauric acid; succinoylating egg white avidin prior to adsorption on the gold sols; resuspending the pellets following ultracentrifugation in 5 mM phosphate buffer, pH 7.5; and using the avidin-gold colloids within 4 weeks of production.
mesh_terms: D000818:Animals; D001360:Avidin; D003102:Colloids; D004355:Drug Stability; D005347:Fibroblasts / Q000166:cytology; D006046:Gold; D017979:Gold Colloid; D006652:Histological Techniques; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D051379:Mice; D012995:Solubility
chemical_list: D003102:Colloids; D017979:Gold Colloid; D007202:Indicators and Reagents; C050418:avidin-gold colloids; D001360:Avidin; D006046:Gold