20120122245 | ALLOYED METAL COLLOID - Provided is a metal colloid having higher visibility and higher sensitivity than a gold colloid and a Au-core Pt-shell composite colloid and suitable as a labeling agent for use in a test such as an immunoassay. An alloyed Au/Pt composite colloid formed by mixing a gold salt and a platinum salt with at least one reducing agent selected from the group consisting of an amino acid and a derivative thereof, an oligopeptide and a derivative thereof, and an amino sugar in the presence of an alkali, thereby reducing the gold salt and platinum salt. | 05-17-2012 |