Trastuzumab Modified Barium Ferrite Magnetic Nanoparticles Labeled with Radium-223: A New Potential Radiobioconjugate for Alpha Radioimmunotherapy

• Main Authors: Weronika Gawęda, Marek Pruszyński, Edyta Cędrowska, Magdalena Rodak, Agnieszka Majkowska-Pilip, Damian Gaweł, Frank Bruchertseifer, Alfred Morgenstern, Aleksander Bilewicz
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: Nanomaterials
• Subjects: alpha radioimmunotherapy; radium-223; barium ferrite
• Online Access: https://www.mdpi.com/2079-4991/10/10/2067

Barium ferrite nanoparticles (BaFeNPs) were investigated as vehicles for ²²³Ra radionuclide in targeted α-therapy. BaFe nanoparticles were labeled using a hydrothermal Ba²⁺ cations replacement by ²²³Ra with yield reaching 61.3 ± 1.8%. Radiolabeled nanoparticles were functionalized with 3-phosphonopropionic acid (CEPA) linker followed by covalent conjugation to trastuzumab (Herceptin^®). Thermogravimetric analysis and radiometric method with the use of [¹³¹I]-labeled trastuzumab revealed that on average 19–21 molecules of trastuzumab are attached to the surface of one BaFe–CEPA nanoparticle. The hydrodynamic diameter of BaFe–CEPA–trastuzumab conjugate is 99.9 ± 3.0 nm in water and increases to 218.3 ± 3.7 nm in PBS buffer, and the zeta potential varies from +27.2 ± 0.7 mV in water to −8.8 ± 0.7 in PBS buffer. The [²²³Ra]BaFe–CEPA–trastuzumab radiobioconjugate almost quantitatively retained ²²³Ra (>98%) and about 96% of ²¹¹Bi and 94% of ²¹¹Pb over 30 days. The obtained radiobioconjugate exhibited high affinity, cell internalization and cytotoxicity towards the human ovarian adenocarcinoma SKOV-3 cells overexpressing HER2 receptor. Confocal studies indicated that [²²³Ra]BaFe–CEPA–trastuzumab was located in peri-nuclear space. High cytotoxicity of the [²²³Ra]BaFe–CEPA–trastuzumab bioconjugate was confirmed by radiotoxicity studies on SKOV-3 cell monolayers and 3D-spheroids. In addition, the magnetic properties of the radiobioconjugate should allow for its use in guide drug delivery driven by magnetic field gradient.