Single-domain protein A-engineered magnetic nanoparticles: Toward a universal strategy to site-specific labeling of antibodies for targeted detection of tumor cells

Serena Mazzucchelli, Miriam Colombo, Clara De Palma, Agnese Salvadè, Paolo Verderio, Maria D. Coghi, Emilio Clementi, Paolo Tortora, Fabio Corsi, Davide Prosperi

Research output: Contribution to journalArticlepeer-review

Abstract

Highly monodisperse magnetite nanocrystals (MNC) were synthesized in organic media and transferred to the water phase by ultrasound-assisted ligand exchange with an iminodiacetic phosphonate. The resulting biocompatible magnetic nanoparticles were characterized by transmission electron microscopy, dynamic light scattering, and magnetorelaxometry, indicating that this method allowed us to obtain stable particle dispersions with narrow size distribution and unusually high magnetic resonance T2 contrast power. These nanoparticles were conjugated to a newly designed recombinant monodomain protein A variant, which exhibited a convincingly strong affinity for human and rabbit IgG molecules. Owing to the nature of antibody-protein A binding, tight antibody immobilization occurred through the Fc fragment thus taking full advantage of the targeting potential of bound IgGs. If necessary, monoclonal antibodies could be removed under controlled conditions regenerating the original IgG-conjugatable MNC. As a proof of concept of the utility of our paramagnetic labeling system of human IgGs for biomedical applications, anti-HER-2 monoclonal antibody trastuzumab was immobilized on hybrid MNC (TMNC). TMNC were assessed by immunoprecipitation assay and confocal microscopy effected on HER-2-overexpressing MCF-7 breast cancer cells, demonstrating excellent recognition capability and selectivity for the target membrane receptor.

Original languageEnglish
Pages (from-to)5693-5702
Number of pages10
JournalACS Nano
Volume4
Issue number10
DOIs
Publication statusPublished - Oct 26 2010

Keywords

  • biolabeling
  • breast cancer
  • magnetic nanoparticles
  • phase transfer
  • protein A
  • targeted MRI contrast agents

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)
  • Physics and Astronomy(all)

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