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

Microbial transglutaminase (MTGase) from <i>Streptomyces mobaraensis</i> 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.