Rapid and simple isolation and detection of exosomes using CaTiO3:Eu3+@Fe3O4 multifunctional nanocomposites

Exosomes are potential biomarkers for disease diagnosis and treatment, as well as drug carriers. However, as their isolation and detection remain critical issues, convenient, rapid, low-cost, and effective methods are necessary. In this study, we present a rapid and simple method for directly capturing and analyzing exosomes from complex cell culture media using CaTiO3:Eu3+@Fe3O4 multifunctional nanocomposites. The CaTiO3:Eu3+@Fe3O4 nanocomposites were prepared by high-energy ball-milling and used to isolate exosomes by binding CaTiO3:Eu3+@Fe3O4 nanocomposites and the hydrophilic phosphate head of the exosome phospholipids. Notably, the developed CaTiO3:Eu3+@Fe3O4 multifunctional nanocomposites achieved results comparable with those of commercially available TiO2 and were separated using a magnet within 10 min. Moreover, we report a surface-enhanced Raman scattering (SERS)-based immunoassay for detecting the exosome biomarker CD81. Gold nanorods (Au NRs) were modified with detection antibodies, and antibody-conjugated Au NRs were labeled with 3, 3, diethylthiatricarbocyanine iodide (DTTC) as the SERS tags. A method combining magnetic separation and SERS was developed to detect exosomal biomarker CD81. The results of this study demonstrate the feasibility of this new technique as a useful tool for exosome isolation and detection.