Ionization of hydrophobic
colloidal nanoparticles. (a) Schematic
representation of ionization of alloy metal (FePt) and metal oxide
(Fe3O4) NPs with dopamine and 3,4-DHCA. (b)
Schematic representation of ionization of noble metal (Pd) NPs and
quantum dots (CdSe) with 4-ATP and 4-MCBA. TEM images of (c) ionic
FePt, (g) cubic Fe3O4, (k) Pd, and (o) CdSe
nanoparticles with 3,4-DHCA and 4-MCBA in water, respectively. TEM
images of (d) FePt, (h) cubic Fe3O4, (l) Pd,
and (p) CdSe nanoparticles in hexane. TEM images of (e) ionic FePt,
(i) cubic Fe3O4, (m) Pd, and (q) CdSe nanoparticles
with dopamine and 4-ATP in water, respectively. Corresponding photographic
images of (f) FePt, (j) cubic Fe3O4, (n) Pd,
and (r) CdSe nanoparticles in hexane and water after ligand exchange
and ionization. Scale bar: FePt, Pd, and CdSe are 50 nm. Cubic Fe3O4 is 100 nm.