Abstract Proteins in serum and urine provide diagnostic indications of early cancers, traumatic brain injury (TBI), and other life threatening conditions, but are difficult to detect at ultra-low concentrations. Ultrasensitive protein detection has been achieved using ‘digital’ (i.e. molecular counting) ELISA (dELISA) platforms such as Quanterix’s SiMoA, these instruments require specialized and complex optics for single molecule detection. The parent award for this supplement (RO1 EB031581), is seeking to develop a fully electronic solid-state nanopores (ssNPs) digital assay which will enable low-cost, point-of-care instruments to bring ultrasensitive diagnostics to low resource settings. The supplemental project will explore the feasibility of a parallel alternative to digital biomarker assessment that does not involve ssNPs. Specifically the proposal seeks to leverage the ability of the nanomembrane technology in the McGrath laboratory to ‘catch and display’ nanoparticles that are direct proxies for protein biomarkers. Simply counting the captured fluorescent nanoparticles by microscopy should confirm the presence and the concentration of biomarkers in the original sample. The project will leverage the methods proposed in the parent grant for the transduction of biomarkers in serum and urine samples into ‘proxies.’ In the supplement however, fluorescent nanoparticles will be used as proxies instead of dsDNA molecules to be detected by a ssNP detector in the parent grant. This project structure provides multiple opportunities for doctoral candidate Marlyn Torres to contribute to assay development in the parent grant while developing her own independent strategy. In addition to developing the basic process steps for a ‘catch and display digital assay’ (CAD-DA), Ms. Torres will develop a microfluidic device that makes the biomarker assessment reliable and reproducible. She will also test the efficacy of CAD-DA for bladder cancer and TBI assessment alongside the ssNP assay developed in the parent grant. By comparing and contrasting the performance and limitations of these two techniques, and by contributing to the comparisons made to the Quanterix’s SiMoA in the parent grant, Ms. Torres’ training is sure to make her an expert in modern digital assays and will open numerous opportunities to further pursue her goal of a technical career in medical diagnostics.