Isolation and Detection of Exosomes Using Fe2O3Nanoparticles

Fatema Zerin Farhana, Muhammad Umer, Ayad Saeed, Amandeep Singh Pannu, Mahboobeh Shahbazi, Aiden Jabur, Hyun Jae Nam, Kostya Ostrikov, Prashant Sonar, Shakhawat H. Firoz, Muhammad J.A. Shiddiky

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)


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 develop a simple method for the direct isolation and quantification of disease-specific exosomes. This method utilized a two-step strategy that involved (a) initial isolation of bulk exosomes present in the sample media using tetraspanin biomarker (i.e., CD9)-functionalized C-IONPs and (b) subsequent electrochemical quantification of disease-specific exosomes within the captured bulk exosomes using tumor-specific markers (in this case, the ovarian cancer biomarker CA-125). In the first step, C-IONPs were used as "dispersible nanocarriers"to capture the bulk population of exosomes, and in the second step, they were used as nanozymes to generate an enzyme-catalyzed current indicative of the presence of tumor-specific exosomes. Chronoamperometric analysis showed that the method exhibits an excellent specificity for OVCAR3 cell-derived exosomes (linear dynamic range, 6.25 × 105 to 1.0 × 107 exosomes/mL; detection limit, 1.25 × 106 exosomes/mL) with a relative standard deviation of
Original languageEnglish
Pages (from-to)1175-1186
Number of pages12
JournalACS Applied Nano Materials
Issue number2
Publication statusPublished - 26 Feb 2021


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