A precisely litho‐patterned carbon/silver nanoparticles arrays as a sensitive surface‐enhanced Raman scattering‐based biosensor for kidney disease assessment

Abstract Serum creatinine (Scr) and blood urea nitrogen (BUN) are key biomarkers for assessing human kidney function. Nevertheless, the quantitative and simultaneous detection of these two markers with high efficiency remains a challenge. To address this, a highly sensitive surface‐enhanced Raman scattering (SERS) substrate, composed of carbonized photoresist embedded with silver nanoparticles (C‐AZ/Ag NPs), was developed for the efficient simultaneous detection of Scr and BUN. In the experiments, AZ5214E and silver nitrate (AgNO 3 ) were first mixed in acetonitrile to prepare the precursor solution for UV photolithography. Subsequently, a porous anodic aluminum oxide coated with a thin chromium film served as a mask to transfer the pattern onto the substrate through UV lithography, and the feature size was tuned by controlling the development time. After that, the patterned substrate was carbonized under an argon atmosphere to yield the final C‐AZ/Ag NPs SERS platform. Using rhodamine 6G as a Raman reporter, the optimized C‐AZ/Ag NPs substrate achieved an enhancement factor of 1.27 × 10 8 and a detection limit down to 10 −9 M. Moreover, it exhibited good spectral uniformity with a relative standard deviation of 7.59%. Finally, clinical serum samples were tested for creatinine and urea nitrogen using the C‐AZ/Ag NPs substrate and cross‐validated against colorimetric assays. It demonstrated that the developed SERS platform accurately reproduced the trends of Scr concentration, which show significant potential for future clinical applications.