An implification technology for improving sensitivity when measuring components in biological samples

Abstract

A new technology for improving the sensitivity in measuring components in biological samples is described. The method is based on the use of spherical microbeads (detection beads) which contain a large amount of immobilized enzyme and a reagent with biospecific affinity for the component to be detected. These microbeads have been used in a ‘sandwich reaction’ for visualization of P-fimbriated Escherichia coli which has a known receptor structure (Gal(α1–4)Gal(β)). In the initial step the bacteria were enriched on a solid support (e.g., a plastic film or beads (> 150 μm) to which the receptor structure had been covalently bound. In the next step detection beads coupled with enzyme and receptor structure were added and finally a chromogenic substrate for the enzyme was used for visualization. A sensitivity of 10 5 bacteria/ml was reached. The detection beads are of general utility and might be useful for the detection of lectins on other pathogens.