Novel dimer dsDNA capture probe coupled with 4-MPBA@AuNPs@6-(Fc)HT ratiometric electrochemical biosensor for the detection of high-affinity anti-dsDNA antibodies.

High-affinity anti-double-stranded DNA (anti-dsDNA) antibodies serve as essential biomarkers for systemic lupus erythematosus (SLE), exhibiting particularly strong correlations with active disease manifestations and renal pathology. However, conventional detection methods require urea treatment to quantify these antibodies, necessitated by the heterogeneity of endogenous antibodies, which complicates assay procedures and compromises accuracy. In this study, a novel ratiometric electrochemical (EC) biosensor for the direct detection of high-affinity anti-dsDNA antibodies in serum without additional sample processing has been developed. This biosensor conducted by a novel T(6-4)T dimer dsDNA capture probe and integrated with a self-assembled 4-mercaptophenylboronic acid@gold nanoparticles@6-ferrocenyl-1-hexanethiol (4-MPBA@AuNPs@6-(Fc)HT) composite signal tag. Leveraging the highly specific of the T(6-4)T dimer dsDNA capture probe and multi-amplification capability of 4-MPBA@AuNPs@6-(Fc)HT, the platform exhibited non-specific interferences, higher sensitivity (limit of detection:1.60 IU/mL), and efficient preparation. Clinical serum analysis showed good correlation with indirect immunofluorescence (IIF) (r = 0.629, p < 0.001), superior diagnostic performance (AUC = 0.893 vs. IIF AUC = 0.900) in differentiating SLE patient from healthy control (CON). Notably, EC results correlated more strongly with renal impairment (r = 0.426, p < 0.01) than IIF (r = 0.321, p > 0.05), highlighting its superior clinical utility for monitoring disease. This strategy provides a robust and straightforward approach for serum high-affinity anti-dsDNA antibodies detection, offering significant potential for SLE diagnosis and progression monitoring.