title: Logical regulation of the enzyme-like activity of gold nanoparticles by using heavy metal ions.
abstract: In this study we employed self-deposition and competitive or synergistic interactions between metal ions and gold nanoparticles (Au NPs) to develop OR, AND, INHIBIT, and XOR logic gates through regulation of the enzyme-like activity of Au NPs. In the presence of various metal ions (Ag(+), Bi(3+), Pb(2+), Pt(4+), and Hg(2+)), we found that Au NPs (13 nm) exhibited peroxidase-, oxidase-, or catalase-like activity. After Ag(+), Bi(3+), or Pb(2+) ions had been deposited on the Au NPs, the particles displayed strong peroxidase-like activity; on the other hand, they exhibited strong oxidase- and catalase-like activities after reactions with Ag(+)/Hg(2+) and Hg(2+)/Bi(3+) ions, respectively. The catalytic activities of these Au NPs arose mainly from the various oxidation states of the surface metal atoms/ions. Taking advantage of this behavior, we constructed multiplex logic operations-OR, AND, INHIBIT, and XOR logic gates-through regulation of the enzyme-like activity after the introduction of metal ions into the Au NP solution. When we deposited Hg(2+) and/or Bi(3+) ions onto the Au NPs, the catalase-like activities of the Au NPs were strongly enhanced (>100-fold). Therefore, we could construct an OR logic gate by using Hg(2+)/Bi(3+) as inputs and the catalase-like activity of the Au NPs as the output. Likewise, we constructed an AND logic gate by using Pt(4+) and Hg(2+) as inputs and the oxidase-like activity of the Au NPs as the output; the co-deposition of Pt and Hg atoms/ions on the Au NPs was responsible for this oxidase-like activity. Competition between Pb(2+) and Hg(2+) ions for the Au NPs allowed us to develop an INHIBIT logic gate-using Pb(2+) and Hg(2+) as inputs and the peroxidase-like activity of the Au NPs as the output. Finally, regulation of the peroxidase-like activity of the Au NPs through the two inputs Ag(+) and Bi(3+) enabled us to construct an XOR logic gate.
authors.affiliation: Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Chia-Wen
authors.initials: CW
authors.lastname: Lien
authors.forename: Ying-Chieh
authors.initials: YC
authors.lastname: Chen
authors.forename: Huan-Tsung
authors.initials: HT
authors.lastname: Chang
authors.forename: Chih-Ching
authors.initials: CC
authors.lastname: Huang
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism*; D002374:Catalase / Q000737:chemistry / Q000378:metabolism; D006046:Gold / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry*; D008962:Models, Theoretical; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism; D009195:Peroxidase / Q000737:chemistry / Q000378:metabolism
chemical_list: D001672:Biocompatible Materials; D007477:Ions; D019216:Metals, Heavy; D006046:Gold; D010088:Oxidoreductases; D002374:Catalase; D009195:Peroxidase