Nanoparticle Radioassay for Proteins in Native Membranes - The capability to analyze cellular uptake of physiological and pharmacological compounds with increasing sensitivity and temporal resolution plays a critical role in understanding the underlying molecular pathways involved in human diseases and disorders. Radioisotopes (RI) facilitate highly sensitive detection of these analytes, with minimal perturbation of analyte mass and structure, compared to fluorescent labels and other molecular tags. β-particle emitters, including 32P, 33P, 35S, and 3H are commonly used as biological tracers due to the prevalence of these atoms in biological molecules. Despite the advent of new molecular analysis approaches, RI remain the gold standard in a wide range of high sensitivity, quantitative biological, chemical and environmental studies. RI labels have played a critical role in the investigation of biological systems, for almost a century. Furthermore, improved detection capabilities that enable a broader application of RI detection to new biomedical research questions should prove transformational in high sensitivity biomolecular analyses. In this SBIR application, we propose to continue development of proprietary, IP-protected, innovative core-shell nanomaterials capable of molecularly selective detection of low energy RIs directly in aqueous samples. These nanomaterials will be demonstrated for sensitive binding assays with GPCRs embedded in native membrane compositions, providing the receptor with a native membrane environment and yielding a more complete picture of protein functionality. Such measurements would seed new research investigations and would position Scintillation Nanotechnologies INC as a provider of revolutionary tools for small molecule binding and drug screening.