The subject of the invention is
superparamagnetic nanoparticle probes based on iron oxides, to
advantage magnetite or
maghemite, with modified surface, coated with mono-, di- or polysaccharides from the group including D-
arabinose, D-glucose, D-
galactose, D-
mannose,
lactose,
maltose, dextrans and dextrins, or with amino acids or poly(
amino acid)s from the group including
alanine,
glycine,
glutamine,
asparagine,
histidine,
arginine, L-
lysine, aspartic and
glutamic acid or with synthetic polymers based on (
meth)
acrylic acid and their derivatives selected from the group containing poly(N,N-dimethylacrylamide), poly(N,N-dimethylmethacrylamide), poly(N,N-diethylacrylamide), poly(N,N-diethylmethacrylamide), poly(N-isopropylacrylamide), poly(N-isopropylmethacrylamide), which form a
colloid consisting of particles with narrow distribution with polydispersity index smaller than 1.3, the
average size of which amounts to 0.5-30 nm, to
advantage 1-10 nm, the
iron content is 70-99.9 wt. %, to
advantage 90 wt. %, the modification agent content 0.1-30 wt. %, to advantage 10 wt. %.The particles of size smaller than 2 nm with polydispersity index smaller than 1.1 can be obtained by a
modified method of preparation.
Superparamagnetic nanoparticle probes according to the invention are prepared by pre-
precipitation of colloidal Fe(OH)3 by the treatment of aqueous 0.1-0.2M solution of Fe(III) salt, to advantage FeCl3, with less than an equimolar amount of NH4OH, at 21° C., under
sonication, to which a solution of a Fe(II) salt, to advantage FeCl2, is added in the
mole ratio Fe(III) / Fe(II)=2 under
sonication and the mixture is poured into five- to tenfold, to advantage eightfold,
molar excess of 0.5M NH4OH. The mixture is left aging for 0-30 min, to advantage 15 min, and then the precipitate is repeatedly, to advantage 7-10 times, magnetically separated and washed with deionized water. Then 1-3 fold amount, to advantage 1.5 fold amount, relative to the amount of
magnetite, of 0.1 M
aqueous solution of
sodium citrate is added and then, dropwise, 1-3 fold amount, to advantage 1.5 fold amount, relative to the amount of
magnetite, of 0.7 M
aqueous solution of
sodium hypochlorite. The precipitate is repeatedly, to advantage 7-10 times, washed with deionized water under the formation of colloidal
maghemite to which, after
dilution, is added dropwise, to advantage under 5-min
sonication, an
aqueous solution of a modification agent, in the weight ratio modification agent /
iron oxide=0.1-10, to advantage 0.2 for amino acids and poly(
amino acid)s and 5 for saccharides.The particles smaller than 2 nm with polydispersity index smaller than 1.1 are prepared by mixing at 21° C. 1 volume part of 10-60 wt. %, to advantage 50 wt. %, of an aqueous solution of a saccharide,
disaccharide or
polysaccharide, such as D-
arabinose, D-glucose, D-
galactose, D-
mannose,
lactose,
maltose,
dextran and dextrins, and 1 volume part of aqueous solution of a Fe(II) and Fe(III) salt, to advantage FeCl2 and FeCl3, where the
molar ratio Fe(III) / Fe(II)=2. A 5-15%, to advantage 7.5%, solution of NH4OH is added until pH 12 is attained and the mixture is heated at 60° C. for 15 min. The mixture is then sonicated at 350 W for 5 min and then washed for 24 h by
dialysis in water using a membrane with molecular weight
cut-off 14,000 until pH 7 is reached. The volume of solution is reduced by
evaporation so that the final
dry matter content is 50-100 mg / ml, to advantage 80 mg per 1 ml.
Superparamagnetic nanoparticle probes according to the invention can be used for
labelling cells used in
magnetic resonance imaging for monitoring their movement, localization, survival and differentiation especially in detection of pathologies with
cell dysfunction and of tissue regeneration and also for
labelling and monitoring cells administered for
cell therapy purposes, in particular embryonal stem cells, fetal stem cells, stem cells of an adult human including
bone marrow stem cells, olfactory glial cells, fat tissue cells, in the recipient
organism by magnetic
resonance.The preparation of labelled cells proceeds by adding to the complete culture medium 5-20 μl, to advantage 10 μl, of a
colloid containing 0.05-45 mg
iron oxide per ml, to advantage 1-5 mg
iron oxide per ml of the medium, and culturing the cells for a period of 1-7 days, to advantage for 1-3 days, at 37° C. and 5% of CO2.