Ferric Iron Nanoparticle Formation Mediated By Negatively Charged Polypeptides

The creation of magnetite particles by magnetotactic bacteria has been of great interest for a number of years. Previous studies have shown that magnetite nanocrystals have been synthesized in the presence of recombinant Mms6 protein. Mms6 plays a vital role in the biomineralization of bacterial magnetite nanocrystals. The objective of this research is to determine the effect of functional group type on size and shape of magnetic nanoparticles formed by biomineralization. Control over the size of nanoparticles is paramount. Use of nanoparticles as contrast agents in MRI is advantageous, as they are small enough to be localized in desired region by applying local magnetic fields. Sequences VA-Mms6, VA1, VA2, and VA3 were designed with modifications in the functional groups Mms6 sequence. Solutions of peptide were mixed with ferric and ferro salts and allowed to interact under inert atmosphere. The nanoparticles formed are examined under SEM and TEM and compared for differences. The SEM and TEM images of nanoparticles produced with the aid of the above peptides had similarity to those produced in the magnetotactic bacteria. However, discrete particles with a narrower size range were produced using the peptide VA2. XPS, AFM, DLS and MFM were also done on the synthesized nanoparticles. The results were in good agreement when compared to those with a standard control sample of magnetite nanoparticles. Use of peptides with different functional groups may provide a unique route to produce uniform magnetite nanocrystals with definite control of morphology