SERS substrate of polyamide replicated anodic aluminum oxide nanorod arrays for uremic toxins detection

Highly ordered gold-decorated polyamide nanorod (Au@PANR) arrays were fabricated as sensitive SERS substrates through a template-assisted transfer and covalent functionalization strategy. Polyamide nanorods (PANRs), replicated from anodic aluminum oxide (AAO) templates, were surface-activated via a single-step aqueous photodegradation process to introduce amine groups. Subsequent 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysulfosuccinimide (EDC/NHS)-mediated coupling of 11-mercaptoundecanoic acid (MUA) enabled the high-density immobilization of gold nanoparticles (AuNPs) through robust AuS linkages. FE-SEM characterization confirmed the formation of uniform PANRs with diameters of ∼70 nm and lengths of ∼600 nm, while XRD patterns verified the crystalline nature of the grafted AuNPs. Systematic optimization of the immersion time revealed that a 48-h incubation maximized the SERS enhancement. Using 4-mercaptobenzoic acid (4-MBA) as a probe, the Au@PANR substrate achieved a limit of detection (LOD) of 10^-7 M with a relative standard deviation (RSD) of 6.85%, demonstrating exceptional sensitivity and reproducibility. These results highlight the potential of functionalized polymeric nanostructures for the trace detection of environmental toxins and clinical biomarkers.