| 摘要 |
Magnetic particles coated with cellulose derivatives, e.g. nitrocellulose, link as a support to DNA or RNA sequences. A probe sequence, itself labelled, e.g. with biotin, hybridizes with suitable complementary supported sequences, and the resulting complexes are magnetically separated. Avidin, or streptavidin, then couples with the biotin and the complex is again magnetically separated. The avidin can be already linked with a marker enzyme such as horseradish peroxide, or glucose oxidase, or alkaline phosphatase, or can be subsequently linked thereto. In either case, subsequent contact with a suitable substrate for the enzyme (H2O2, glucose, phenylphosphate) gives a reaction for electrochemical measurement either via a ferrocene mediator compound (H2O2, glucose) or by oxidation at an electrode surface (phenol from phenyl phosphate). This reaction eventually relates back very sensitively to the presence or amount of initial hybridisation; attomole quantities are measurable. |
