Organometallic Complexes as Tracers in Non-isotopic Immunoassay

Since the subject of the immunoassay may not be familiar to readers whose interests are in the field of organometallic chemistry, we will begin this chapter with a brief overview of the prindple behind the immunoassay method before describing the synthesis of organometallic tracers and reviewing the various detection methods that have facilitated the creation of novel immunoassays. 

An immunoassay is the indirect assay of an analyte whose concentration in a matrix (blood, plasma, urine, drinking water, etc.) is at most several micrograms/ litre. It is based on the specific interaction between three components (Fig. 8.1) the analyte (antigen) to be assayed, a specific (polyclonal or monodonal) antibody of the analyte, plus a tracer consisting of the analyte (antigen) or the antibody, modified by addition of a label that can be detected at the nanomolar (or better, at the picomolar) level by an analytical technique such as radioactivity, enzymatic detection, electrochemical detection, atomic absorption spectroscopy (AAS), Fourier-transform infrared (FT-IR) spectroscopy, or fluorescence polarization (FP). 

Substances for analysis can be divided into three categories (1) haptens, which are molecules with a molecular weight of less than 1 kD. These include steroids, medications, illegal substances, pesticides (2) proteins such as tumoral markers, antibodies, P-HCG (3) viruses. 

A hapten (steroid or thyroid hormones, drugs, prescription drugs, peshcides, etc...) 

Spedfic antibodies for the analyte to be tested (polyclonal or monoclonal) 

---