A metal oxide nanoparticle comprises a metal oxide core of formula M2O5, wherein M is tantalum (V) or niobium (V) and alkylsiloxane ligands bonded to the metal oxide core. The alkylsiloxane ligands are selected from the group consisting of isobutylsiloxane, allylsiloxane, vinylsiloxane, n-propyl siloxane, n-butylsiloxane, sec-butyl siloxane, tert-butyl siloxane, phenylsiloxane, n-octylsiloxane, isooctylsiloxane n-dodecyl siloxane, 4 -(trimethyl silyl)phenylsiloxane, para-tolylsiloxane, 4-fluorophenyl siloxane, 4 -chlorophenyl siloxane, 4-bromophenyl siloxane, 4-iodophenylsiloxane, 4-cyanophenyl siloxane, benzylsiloxane, methylsiloxane, ethylsiloxane, 4-(trifluoromethyl)phenylsiloxane, 4 -ammoniumbutylsiloxane, and any combination thereof.