Abstract: An assay exhibiting improved sensitivity for achieving a factor of ten times (10×) better sensitivity than current sensitivity levels achieved by prior-art immunoassays, as exemplified by ELISA. Three main implementations are described: IA/MPD, Super-ELISA and Reverse Geometry Immunoassay, including specific panel biomarker relationships for the early detection and recognition patterns of breast and prostate cancers. More sensitive immunoassays are achieved through a better understanding of sources of biological background, and by the rejection of particular sources thereof. Super-sensitive immunoassays permit measurement of blood sample biomarkers, and show distribution of low abundance proteins included relationships between cytokine non-Gaussian distributions, very large dynamic ranges and strong age dependence, and including new algorithms based on 2D correlations of studied biomarkers.

Abstract: A method for detecting an analyte of interest present in a mixture at an ultralow concentration includes selecting a radioactive derivatizing agent comprising a multiphoton-emitting radioisotope moiety and a moiety reactive with the analyte of interest, the radioisotope moeity being bound to the derivatizing agent by a bond that is stable under the conditions employed in the other steps of the method, derivatizing the analyte of interest with the derivatizing agent, separating the analyte of interest from other components of the mixture by chromatography, and detecting the analyte of interest using multiphoton detection. The derivatizing step may be performed before or after fractionation. A radiophore for multiphoton emission enhanced chromatography has a first moeity bound to a multiphoton-emitting radioisotope, and a second moiety that is reactive with a functional group of an analyte of interest.

Abstract: An ultralow background multiphoton detectors device for radioisotopes has a background of about one count per day. Two opposed gamma and X-ray photon detectors each preferably include a scintillation crystal and a photomultiplier tube. Sandwiched between the detectors are a separator and a sample holder for a sample labelled with a radioisotope such as I.sup.125. The detectors convert emissions from the radioisotope into electric output pulses which are then subjected to signal processing for pulse shape analysis, discrimination of coincident from non-coincident events, and quantification of the radioisotope. Detector materials and components are selected to minimize background, and are shielded from external radiation. The device may further be constructed to resolve and provide images of two dimensional sample arrays.

Abstract: A method for detecting an analyte of interest present in a mixture at an ultralow concentration includes selecting a radioactive derivatizing agent comprising a multiphoton-emitting radioisotope moiety and a moiety reactive with the analyte of interest, the radioisotope moeity being bound to the derivatizing agent by a bond that is stable under the conditions employed in the other steps of the method, derivatizing the analyte of interest with the derivatizing agent, separating the analyte of interest from other components of the mixture by chromatography, and detecting the analyte of interest using multiphoton detection. The derivatizing step may be performed before or after fractionation. A radiophore for multiphoton emission enhanced chromatography has a first moeity bound to a multiphoton-emitting radioisotope, and a second moiety that is reactive with a functional group of an analyte of interest.

Abstract: For isotopes decaying by capture of an inner shell electron by the nucleus, coincident emission of X-ray and gamma photons may occur. The X-ray results from the drop of an outer shell electron to fill the S shell. The gamma results from the transition of the excited daughter nucleus to a lower energy state. The invention disclosed is a Coincident Gamma and X-ray Detector (CGXD) which achieves extraordinary background rejection by a synergistic combination of coincident counting and other background suppression measures. Whereas the background registered by single gamma counters is of the order of 20-40 counts per minute, a CGXD optimized for the electron capture radioisotope I.sup.125 has a background of about one count per day.