Biodiagnostic Assay Using Multibranched Gold Nanoantennas for Ultra-Sensitive Biomarker Detection Via Sandwich Architecture

This system utilizes the plasmon enhancement capabilities of multi-branched gold nanoantennas (MGNs) to achieve ultra sensitive and specific detection of Prostate Specific Antigen (PSA) via Surface Enhanced Raman Spectroscopy (SERS). This extremely low detection limit of PSA was achieved with a biodiagnostic sandwich architecture consisting of a glass substrate coated with anti:PSA MGNs along with a top MGN probe functionalized with an additional anti:PSA and Raman tag for recognition. One early indicator of prostate cancer is the elevation of PSA levels in the blood due to tumor formation in the region. By improving the detection limit for this PSA biomarker, the early onset of this disease can be screened and subsequently treated early in its progression. In order to determine the PSA detection limit of the assay, different concentrations of the antigen were incorporated and then analyzed via SERS. A detection limit of 5 fg/mL PSA was achieved. In addition to these PSA sensitivity trials, a non-specific protein, immunoglobulin, was analyzed to test the specificity of this assay. These experiments demonstrate the biomarker detection capabilities and provide a platform for future detection of other cancer biomarkers.