Self-assembled gold nanocrystal micelles act as an excellent artificial nanozyme with ribonuclease activity

摘要

Water-soluble Au nanocrystal (NC) micelles with an inserted catalytic Cu(II) center that act as excellent nanoenzyme models for imitating ribonuclease were con_structed by supramolecular self-assembly. The dodecane- 1- thiol-based Au NC was constructed first, and subsequently the cationic surfactant hexadecyltrimethylammonium bro_mide and the catalytic ligand (N~1 ,N~1-bis(2-aminoethyl)- N~2-dodecylethane-1,2-diamine) copper(II) were installed on the surface of the Au NC via hydrophobic interaction. The catalytic capability of the Au NC micelles designed was estimated by the cleavage of a typical RNA analogue, 2-hydroxypropyl p-nitrophenyl phosphate (HPNP). The study of the catalytic behavior of Au NC micelle catalysis showed that the Au NC micelles exhibited dramatic ribonuclease-like activity: a high rate acceleration of k_(cat)/k_(uncat) = 1.10 × 10~5 for the cleavage of HPNP in comparison with the spontaneous cleavage of HPNP (k_(uncat)) was observed. The catalytic capability for HPNP cleavage by these functionalized Au NC micelles can be compared with that of covalent Au nanoparticles reported previously as nanozymes under comparable conditions. A detailed investigation of enzymatic kinetics was carried out and a possible mechanism was suggested.