Tuning properties of biomimetic magnetic nanoparticles by combining magnetosome associated proteins

Abstract

The role of magnetosome associated proteins on the in vitro synthesis of magnetite nanoparticles has gained interest, both to obtain a better understanding of the magnetosome biomineralization process and to be able to produce novel magnetosome-like biomimetic nanoparticles. Up to now, only one recombinant protein has been used at the time to in vitro form biomimetic magnetite precipitates, being that a scenario far enough from what probably occurs in the magnetosome. In the present study, both Mms6 and MamC from Magnetococcus marinus MC-1 have been used to in vitro form biomimetic magnetites. Our results show that MamC and Mms6 have different, but complementary, effects on in vitro magnetite nucleation and growth. MamC seems to control the kinetics of magnetite nucleation while Mms6 seems to preferably control the kinetics for crystal growth. Our results from the present study also indicate that it is possible to combine both proteins to tune the properties of the resulting biomimetic magnetites. In particular, by changing the relative ratio of these proteins, better faceted and/or larger magnetite crystals with, consequently, different magnetic moment per particle could be obtained. This study provides with tools to obtain new biomimetic nanoparticles with a potential utility for biotechnological applications.

Biomineralization of Magnetosomes: Billion-Year Evolution Shaping Modern Nanotools

“…Due to its effect over synthesis, this protein has been expressed for use in different biomimetics studies ( Figure 5). Different coprecipitation experiments have shown an increase from ~10-25 nm, in control synthesis, to ~30-40 nm, when recombinant MamC from strain MC-1 is added in concentrations over 10 μg/mL [79,84].…”

“…MamC protein from Magnetococcus marinus strain MC-1 has an effect of enlarging magnetite precipitates [79,84]. Due to its effect over synthesis, this protein has been expressed for use in different biomimetics studies ( Figure 5).…”

“…Thus, the ionotropic (i.e. iron-affinity) effect of MamC does not give sufficient ground for the role of this protein in biomineralization [84,91,92]. MamC must exert a template effect in magnetite formation [84].…”

“…iron-affinity) effect of MamC does not give sufficient ground for the role of this protein in biomineralization [84,91,92]. MamC must exert a template effect in magnetite formation [84]. In the MM, MamC is constituted by two transmembrane domains connected by alpha-helical looping, which contacts the forming magnetite within the magnetosome vesicle lumen [92].…”

“…The alpha-helical conformation of the MamC-MIC ensures the proper positioning of the points of interaction with iron [91]. The complementary roles of MamC and Mms6 can be combined in a biomimetic synthesis, yielding large magnetosomes (30 ± 10 nm) with well-defined crystal faces [84].…”