High-Affinity Aptamer Selection for Microbial Transglutaminase and Application in Colorimetric–SERS Dual-Mode Detection

Microbial transglutaminase (MTGase) from Streptomyces mobaraensis is widely used in food processing to improve texture but poses health risks due to immune reactions and masking raw material quality. This study developed a sensitive detection method using a high-affinity aptamer (S1) selected via Capture-SELEX with a dissociation constant of 24.32 ± 5.85 nM. Binding was verified by ITC and fluorescence polarization, and the recognition mechanism was explored by CD spectroscopy and molecular docking. A dual-mode colorimetric and SERS aptasensor was constructed based on MIL-101(Fe)@MoS2@AuNPs, where MIL-101 acted as a porous scaffold, MoS2 enhanced electron transfer, and Au nanoparticles improved catalytic and SERS properties. Magnetic Fe3O4 NPs enabled target enrichment and separation, while catalytic hairpin assembly amplified the signal. The sensor showed a linear detection range of 1-2000 ng/mL for MTGase, with limits of 0.46 ng/mL (colorimetric) and 0.16 ng/mL (SERS). This aptasensor offers high sensitivity, specificity, and stability for food safety monitoring and biosensing applications.