Rapid and portable detection of foodborne pathogens is of great significance for food safety and public health. The colorimetric methods based on naked-eye have been demonstrated to be a suitable qualitative method for point-of-care testing (POCT). However, analytical instruments like a microplate reader must be needed for the quantitative assay. To overcome its limitation, we herein report a novel photothermal method for foodborne pathogens based on the photothermal effect of aggregated mercaptophenylboronic acid-functionalized AuNPs (MPBA-AuNPs) induced by MPBA to translate the colorimetric detection into a simple temperature measurement using thermometers as the readout. The aggregated AuNPs show higher photothermal conversion efficiency than well-separated AuNPs under 660 nm laser irradiation. In the presence of bacteria, MPBA-AuNPs will attach to the surface of bacteria and keep separated from aggregation induced by excess MPBA, resulting in a lower temperature increase under 660 nm laser irradiation. Using E. coli O157:H7 as a model target, a good linear relationship is observed between temperature increase and bacteria concentration from 1.00 × 10 5 -1.00 × 10 9 cfu mL −1 (R 2 = 0.9877) with a detection limit of 1.97 × 10 4 cfu mL −1 , which is three orders of magnitude lower than of the MPBA-AuNPs-based colorimetric assays . The proposed photothermal method provided a universal platform for rapid and portable detection of broad-spectrum bacteria strains in real samples.
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.
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