Enzymatic synthesis of magnetic nanoparticles

Arati G. Kolhatkar, Chamath Dannongoda, Katerina Kourentzi, Andrew C. Jamison, Ivan Nekrashevich, Archana Kar, Eliedonna Cacao, Ulrich Strych, Irene Rusakova, Karen S. Martirosyan, Dmitri Litvinov, T. Randall Lee, Richard C. Willson

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


We report the first in vitro enzymatic synthesis of paramagnetic and antiferromagnetic nanoparticles toward magnetic ELISA reporting. With our procedure, alkaline phosphatase catalyzes the dephosphorylation of L-ascorbic-2-phosphate, which then serves as a reducing agent for salts of iron, gadolinium, and holmium, forming magnetic precipitates of Fe45±14Gd5±2O50±15 and Fe42±4Ho6±4O52±5. The nanoparticles were found to be paramagnetic at 300 K and antiferromagnetic under 25 K. Although weakly magnetic at 300 K, the room-temperature magnetization of the nanoparticles found here is considerably greater than that of analogous chemically-synthesized LnxFeyOz (Ln = Gd, Ho) samples reported previously. At 5 K, the nanoparticles showed a significantly higher saturation magnetization of 45 and 30 emu/g for Fe45±14Gd5±2O50±15 and Fe42±4Ho6±4O52±5, respectively. Our approach of enzymatically synthesizing magnetic labels reduces the cost and avoids diffusional mass-transfer limitations associated with pre-synthesized magnetic reporter particles, while retaining the advantages of magnetic sensing.

Original languageEnglish (US)
Pages (from-to)7535-7550
Number of pages16
JournalInternational journal of molecular sciences
Issue number4
StatePublished - Apr 3 2015


  • Alkaline phosphatase
  • Enzymatic synthesis
  • Magnetic nanoparticles
  • Magnetic sensing

ASJC Scopus subject areas

  • Catalysis
  • Molecular Biology
  • Spectroscopy
  • Computer Science Applications
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry


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