Abstract: The assay of the subject invention uses DNA sequences as probes in a nucleic acid hybridization diffraction assay, to detect specific DNA sequences in a sample. Diffraction assay methodologies are applied to determine the presence and amount of analyte.This invention involves a discovery in the areas of supporting surfaces for a biogrid or biograting which provide greatly reduced non-specific hybridization and binding. A preferred process of this invention involves manufacturing a biograting for use in a light diffraction assay, and comprises adhering a uniform layer of hybridizing reagent comprising a nucleotide sequence on a smooth, solid surface and exposing the surface to UV radiation through a shadow mask with a diffraction grating pattern of lines to selectively deactivate the hybridizing reagent, leaving a biological diffraction grating design of lines of active hybridizing reagent.

Abstract: Preeclampisa, pregnancy induced hypertension (PIH) and eclampsia are determined by identifying the presence of an endothelial cell marker in a sample of blood, plasma or serum of a pregnant woman using a sandwich or competition immunoassay. Cellular fibronectin marker in a sample is determined by binding with an anti-(cellular fibronectin) antibody. Reagents for these methods are also an aspect of the invention.