Label-Free SERS Strategy for Simultaneous Detection of Triplex Renal Biomarkers in Serum toward Precise Renal Function Evaluation

Serum creatinine (SCr), blood urea nitrogen (BUN), and serum uric acid (SUA) are key biomarkers for renal function assessment, with urgent clinical need for their rapid multiplex detection. Despite the significant advantages and potential of surface-enhanced Raman spectroscopy (SERS), the complex serum matrix and overlapping Raman signals of targets severely impede highly sensitive simultaneous analysis. This study developed an Au@Ag@inositol hexaphosphate (IP6) nanostructured SERS substrate, which integrates the high plasmonic activity of Au@Ag and IP6's strong hydrogen-bonding ability to amine-containing targets, enabling selective enrichment and sensitive detection of SCr, BUN and SUA. Concurrently, a rapid methanol pretreatment and a pH-regulation strategy were established. The former removes interfering serum proteins within 3 min to enhance target enrichment, while the latter regulates pH to balance analyte adsorption, eliminating SERS peak overlap for reliable multiplex analysis. Based on these methods, linear models for qualitative and quantitative detection of SCr, BUN and SUA in serum were constructed. Validation with 44 clinical samples (23 uremia patients, 21 healthy controls) showed 100% diagnostic accuracy for uremia, with quantitative results highly consistent with hospital reports. This work provides a reliable novel SERS strategy for simultaneous detection of the three renal biomarkers in serum, exhibiting great potential for clinical diagnosis of uremia and hyperuricemia.