Advancing Protein\nDetection and Analysis Based on\nAg/Au PHCN for Enhanced SERS Sensitivity and Specificity in Biomolecular\nDiagnostics

In the realm of disease diagnostics,\nparticularly for conditions\nsuch as proteinuria and hemoglobinuria, the quest for a method that\ncombines accurate, label-free detection of protein compositions and\ntheir conformational changes remains a formidable challenge. In this\nstudy, we introduce an innovative Ag/Au plasmonic hybrid coupling\nnanoarray (Ag/Au PHCN) architecture marked by sub-10 nm interparticle\ngaps. These nanoarrays, leveraging plasmonic hybrid coupling and synergistic\nenhancement mechanisms, create a plethora of uniform surface-enhanced\nRaman spectroscopy (SERS) hotspots. The Ag/Au PHCN substrates demonstrated\nunparalleled sensitivity in the unmarked detection of hemoglobin (HGB),\nbovine serum albumin (BSA), and cytochrome C (Cyt.C) in bodily fluids,\nincorporating the advantages of high sensitivity, high reproducibility,\ndurability, recyclability, and biocompatibility. Notably, the detection\nlimits for BSA and HGB are unprecedented at 0.5 and 5 ng/mL, respectively.\nThis achievement sets a new benchmark for label-free protein detection\nusing two-dimensional nanostructures. Crucially, the Ag/Au PHCNs possess\nthe novel capability to discern protein conformational changes post\ndenaturation, underscoring their potential in probing protein functionalities.\nMost importantly, these nanoarrays can differentiate between normal\nand proteinuria-affected urine samples and monitor protein content\nvariations over time, heralding a new era in clinical diagnostics\nwith particular relevance to proteinuria and hemoglobinuria detection.