An Ultrasensitive Electrochemical Aptasensor for Thrombin Detection Using MoS2 Nanoparticles Loaded Iron-Porphyrinic Metal-Organic Framework as Signal Amplifier

Abstract

An ultrasensitive electrochemical aptasensor for thrombin (TB) was designed using MoS2 nanoparticles loaded iron-porphyrinic metal-organic framework (PCN-223-Fe) as the electrochemical tracer. Spindle-shaped PCN-223-Fe was synthesized with zirconium ion as node and iron-porphyrin as linker, and in situ loaded with MoS2 nanoparticles to obtain MoS2/PCN-223-Fe composite. MoS2/PCN-223-Fe was characterized by electron microscopies, X-ray diffraction and X-ray photoelectron spectroscopy. Due to the synergistic effect of MoS2 and PCN-223-Fe, MoS2/PCN-223-Fe modified electrode exhibited enhanced electrocatalytic activity to oxygen reduction. Sequentially, MoS2/PCN-223-Fe was combined with TB aptamer 2 to prepare signal probe. A sandwich-type electrochemical aptasensor was constructed for TB detection. TB aptamer 1 was fixed on electrode surface to capture TB molecules, and then TB aptamer 2 functionalized MoS2/PCN-223-Fe tracer was introduced on electrode surface. By detecting the electrochemical signal of oxygen reduction catalyzed by MoS2/PCN-223-Fe, the designed TB sensor was monitored. The proposed TB aptasensor showed a wide linear range from 0.1 pM to 100 nM and a low detection limit of 0.03 pM (S/N = 3). Meanwhile, the aptasensor showed good reproducibility, stability and selectivity, which was successfully applied for TB detection in human serum sample. This strategy broadens application of metal-organic frameworks, and could be used for other biomolecules detection.