A visual peroxidase mimicking aptasensor based on Pt nanoparticles-loaded on iron metal organic gel for fumonisin B₁ analysis in corn meal

A visual colorimetric aptasensor combining platinum nanoparticles (Pt NPs) loaded on Fe-based metal organic gel (Fe-MOG) as peroxidase mimics with magnetic separation technique was designed for the detection of fumonisin B₁ (FB₁). Interestingly, based on the inherent properties of Fe-MOG such as porous nanostructures, abundant Fe²⁺/Fe³⁺ active metal centers and synergetic effect between Pt NPs and Fe-MOG, Pt NPs/Fe-MOG composites can be employed as excellent peroxidase mimetic enzyme to oxidize 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H₂O₂. This process was accompanied by a color variation of the solution from colorless to blue. Kinetic analysis showed that the Pt NPs/Fe-MOG composites make an effective peroxidase mimic with low Michaelis constant (K_m), high substrate binding affinity and rapid catalytic velocity (V_m). Furthermore, the Pt NPs/Fe-MOG based colorimetric aptasensor was used to detect FB₁. The prepared Pt NPs/Fe-MOG achieved lower detection limit (2.7 pg/mL, 3σ/k) with a wide linear range of 0.01-2000.0 ng/mL. Finally, as a proof of concept of the rapidity and the simplicity of this colorimetric aptasensor, Pt NPs/Fe-MOG was used for the detection of FB₁ in real corn samples.