Isolation and Detection of Exosomes Using Fe₂O₃ Nanoparticles

Magnetic nanozymes with peroxidase-mimicking activity have been widely investigated for developing molecular biosensors. Herein, we report a starch-assisted method for the synthesis of a novel class of carboxyl group-functionalized iron oxide nanoparticles (C-IONPs). Scanning electron and transmission electron microscopy analysis revealed that the nanoparticles possess a spherical shape with an average size of ∼250 nm. Peroxidase-mimicking activity of C-IONPs was investigated through catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2. The results showed that nanoparticles follow typical Michaelis–Menten kinetics and exhibit excellent affinity toward TMB and H2O2 with estimated KM and VMax values of 0.0992 mM and 0.156 × 10–8 Ms–1 for TMB and 114 mM and 0.197 × 10–8 Ms–1 for H2O2, respectively. C-IONPs were used to…