AM Biotechnologies (AM) will develop a system to detect and quantify bone demineralization biomarkers as outlined in SBIR Topic "Technologies to Detect Biomarkers". AM will enhance the current clinical gold standard immunoassay methodology by using its proprietary bead-based aptamer selection process to select dithiophosphate backbone-modified (PS2) "thio" aptamers (PS2-thioaptamers) as replacements for antibodies in immunoassays. The PS2-thioaptamers are binding agents with functionality comparable to antibodies but with very long shelf-life under ambient environment storage. The PS2-thioaptamers bind much more tightly to their targets than regular aptamers without sacrificing specificity, and are much more nuclease resistant. AM's bead-based process allows selection and identification of PS2-thioaptamers, which cannot be directly selected using older aptamer technologies such as Systematic Evolution of Ligands by Exponential Enrichment (SELEX). AM will also demonstrate PS2-thioaptamer integration into a state-of-the-art microfluidics instrument from Sandia National Laboratory that meets NASA's form factor needs for space flight. The Phase I Project will demonstrate detection and quantification of osteocalcin (OC) using a PS2-thioaptamer in a prototype microfluidics device (TRL-4). Phase II will entail completing the panel of biomarkers for bone demineralization and delivering a prototype of the system to NASA. In Phase III, AM and Sandia will deliver a flight test system to NASA and begin FDA validation of the system for potential use in clinical diagnostics of osteoporosis as well as other conditions.