Construction and application of thrombin-activated fluorescence-SERS dual-mode optical nanoprobes.

Thrombin (TB) plays a key role in the pathological and physiological coagulation of diseases. In this work, a TB-activated fluorescence-surface-enhanced Raman spectroscopy (SERS) dual-mode optical nanoprobe (MRAu) was constructed by linking rhodamine B (RB)-modified magnetic fluorescent nanospheres with AuNPs through TB-specific recognition peptides. In the presence of TB, the polypeptide substrate could specifically be cleaved by TB, resulting in the weakening of SERS hotspot effect and the reduction of Raman signal. Meanwhile, the fluorescence resonance energy transfer (FRET) system was destroyed, and the RB fluorescence signal originally quenched by AuNPs was recovered. Using MRAu, SERS and fluorescence methods were combined to extend the TB detection range to 1-150 pM, and the detection limit was as low as 0.35 pM. In addition, the ability to detect TB in human serum also verified the effectiveness and practicality of the nanoprobe. The probe was also successfully employed to evaluate the inhibitory effect against TB of active components in Panax notoginseng. This study provides a new technical means for the diagnosis and drug development of abnormal TB-related diseases.