A nanoassembly system comprising - a nanoassembly comprising: ∘ an organic fluorescent inner core comprising fluorescent organic molecules, and ∘ magnetic nanoparticles contacting the surface of said fluorescent inner core; and - at least one polymer adsorbed at the surface of the nanoassembly; provided that the nanoassembly system does not comprise silica, functionalized silica, doped silica, grafted silica or a combination thereof, wherein the fluorescent organic molecules are compounds of Formula (I), wherein: L represents a spacer selected from (i), (ii) and (iii) X represents O, CH 2 or NR 8 , wherein R 8 represents H, alkyl or alkene; X' represents O or NR 9 , wherein R 9 represents H, alkyl or alkene; n represents an integer selected from 1, 2, 3 and 4; R 1 represents -CO 2 H or -P(O)(OH) 2 ; R 2 , R 3 , R 4 , R 5 , R 6 and R 7 represent each independently an optionally functionalized group selected from alkyl and ester or poly(ethylene glycol), preferably R 2 , R 3 , R 4 , R 5 , R 6 and R 7 represent each a methyl group, and wherein the magnetic nanoparticles are selected from the group consisting of γ-Fe 2 O 3 , Fe 3 O 4 , CoFe 2 O 4 , MnFe 2 O 4 , CuFe 2 O 4 and NiFe 2 O 4 . - a nanoassembly comprising: ∘ an organic fluorescent inner core comprising fluorescent organic molecules, and ∘ magnetic nanoparticles contacting the surface of said fluorescent inner core; and ∘ an organic fluorescent inner core comprising fluorescent organic molecules, and ∘ magnetic nanoparticles contacting the surface of said fluorescent inner core; and - at least one polymer adsorbed at the surface of the nanoassembly; provided that the nanoassembly system does not comprise silica, functionalized silica, doped silica, grafted silica or a combination thereof, wherein the fluorescent organic molecules are compounds of Formula (I), wherein: L represents a spacer selected from (i), (ii) and (iii) X represents O, CH 2 or NR 8 , wherein R 8 represents H, alkyl or alkene; X' represents O or NR 9 , wherein R 9 represents H, alkyl or alkene; n represents an integer selected from 1, 2, 3 and 4; R 1 represents -CO 2 H or -P(O)(OH) 2 ; R 2 , R 3 , R 4 , R 5 , R 6 and R 7 represent each independently an optionally functionalized group selected from alkyl and ester or poly(ethylene glycol), preferably R 2 , R 3 , R 4 , R 5 , R 6 and R 7 represent each a methyl group, and wherein the magnetic nanoparticles are selected from the group consisting of γ-Fe 2 O 3 , Fe 3 O 4 , CoFe 2 O 4 , MnFe 2 O 4 , CuFe 2 O 4 and NiFe 2 O 4 . L represents a spacer selected from (i), (ii) and (iii) X represents O, CH 2 or NR 8 , wherein R 8 represents H, alkyl or alkene; X' represents O or NR 9 , wherein R 9 represents H, alkyl or alkene; n represents an integer selected from 1, 2, 3 and 4; R 1 represents -CO 2 H or -P(O)(OH) 2 ; R 2 , R 3 , R 4 , R 5 , R 6 and R 7 represent each independently an optionally functionalized group selected from alkyl and ester or poly(ethylene glycol), preferably R 2 , R 3 , R 4 , R 5 , R 6 and R 7 represent each a methyl group, and wherein the magnetic nanoparticles are selected from the group consisting of γ-Fe 2 O 3 , Fe 3 O 4 , CoFe 2 O 4 , MnFe 2 O 4 , CuFe 2 O 4 and NiFe 2 O 4 . <EOS>