Cellular production of pure iron oxide nanoparticles

High purity magnetosomes produced by magnetotactic bacteria, comprising a magnetosome composition and a structure that comprises at least (i) a magnetosome central part or magnetosome mineral or magnetosome core and optionally (ii) a magnetosome coating surrounding the magnetosome mineral or magnetosome central part or magnetosome core;

• wherein the magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition comprises a metallic composition, the metallic composition is characterized by at least one property selected from the group consisting of:
• i) a mass of Cd comprised in 1 gram of or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition, is smaller than 35 μg,
• ii) a percentage in mass of Cd comprised in the magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 3·10−3%,
• iii) a mass of Pb comprised in 1 gram of or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition, is smaller than 5000 μg,
• iv) a percentage in mass of Pb comprised in the or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 5·10−1%,
• v) amass of Ni comprised in 1 gram of or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 200 μg,
• vi) a percentage in mass of Ni comprised in the or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 10−2%,
• vii) a mass of Co comprised in 1 gram of or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 100 μg,
• viii) a percentage in mass of Co comprised in the or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 10−2%,
• ix) a mass of Al comprised in 1 gram of or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 500 μg,
• x) a percentage in mass of Al comprised in the or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 5·10−2%,
• xi) a mass of Zn comprised in 1 gram of or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 500 μg,
• xii) a percentage in mass of Zn comprised in the or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 5·10−2%,
• xiii) a mass of Mn comprised in 1 gram of or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 1000 μg,
• xiv) a percentage in mass of Mn comprised in or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 1%,
• xv) a mass of Li comprised in 1 gram of magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 50 μg,
• xvi) a percentage in mass of Li comprised in the or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 5·10−3%,
• xvii) a mass of Cu comprised in 1 gram of or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 100 μg,
• xviii) a percentage in mass of Cu comprised in the or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is smaller than 10−2%,
• and
• xix) in or for a given or fixed quantity or mass of Fe comprised in the or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition, a quantity or mass of at least one metal comprised in the or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition selected from the group consisting of:
• Cd, Pb, Ni, Co, Al, Mn, Zn, Li, and Cu, is at least 10 times smaller than a quantity or mass of Mg comprised in the or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition,
• wherein a mass of or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is estimated as or corresponds to a mass of Fe comprised in or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition,
• wherein a percentage in mass of at least one compound comprised in the or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition is estimated relatively to amass of all metals or of Fe and/or Mg comprised in the or magnetosome mineral or magnetosome core or magnetosome central part or magnetosome coating or magnetosome composition,
• wherein the at least one metal originates from the pre-growth and/or growth and/or fed-batch medium(a).