Selection and application of aptamers targeting the Brucella BP26 protein

Rapid and specific detection of Brucella remains a challenge due to the limitations of conventional serological and molecular methods. In this study, we developed an aptamer magnetic capture (AMC) qPCR platform for the sensitive detection of Brucella. The recombinant outer membrane protein BP26 was expressed, purified, and utilized as the target for aptamer selection via a magnetic cross-linking precipitation (MCP) SELEX strategy. After eight rounds of selection, two DNA aptamers (B1 and B3) were identified, exhibiting high affinities with dissociation constants (K_d) of 69.42 nM and 47.40 nM, respectively. By integrating these aptamers with magnetic separation and qPCR, the developed AMC-qPCR assay achieved a limit of detection (LOD) of 1.8 log₁₀ CFU per 500 μL, with capture efficiencies ranging from 15% to 61%, demonstrating effective target enrichment and sensitive detection.