Catalytic hairpin assembly-assisted dual-enhanced SERS satellite nanocomplex for ultrasensitive detection of lipopolysaccharides in injection samples

Rapid and sensitive detection of pathogenic lipopolysaccharide (LPS) is of the utmost importance in pharmaceutical products and food safety. Herein, we presented catalyzed hairpin assembly (CHA)-mediated magnetic/plasmonic satellite nanoassemblies, made of ternary metallic Au@AgPt-coated metal-organic framework (MOF) nanohybrids (Au@AgPt@MOF) with dual-enhancement SERS output and Au magnetic nanoparticles (AuMNPs) with magnetic enrichment and SERS amplification, for ultrasensitive sensing LPS in pharmaceutical injections. Target LPS initiated aptamer (Apt)-based chain replacement reaction, thereby activating downstream CHA for inducing the aggregation of large satellite nanoassemblies and the amplification of catalytic/SERS signals. Under the optimal condition, this method exhibited good linear response in the range of 10 −5 -10 3 ng/mL, with an ultralow limit of detection (LOD) in SERS model (8 fg/mL) and catalytic colorimetric model (56 fg/mL). The selectivity and sensitivity of oligonucleotide-driven signal amplification was validated by in vitro experiments and trials of glucose, troxerutin, lidocaine hydrochloride injection samples. The assay results were closely aligning with those of the standard endotoxin quantitative kit, demonstrating the reliability and availability of this assay. Overall, by incorporating the merits of dual-SERS enhancement of Au@AgPt@MOF substrate, magnetic-meditated satellite strategy, and CHA-cascade amplification response, this platform opened up new opportunities for inspecting LPS in drug injection samples.