Visual detection of copper(II) ions in blood samples by controlling the leaching of protein-capped gold nanoparticles

• Published in: Analyst (London) Vol. 137; no. 8; p. 1800
• Main Authors: Lee, Yen-Fei, Deng, Ting-Wei, Chiu, Wei-Jane, Wei, Tsao-Yen, Roy, Prathik, Huang, Chih-Ching
• Format: Journal Article
• Language: English
• Published: England 21-04-2012
• Subjects: Copper - blood; Gold - chemistry; Lead - chemistry; Membranes, Artificial; Mercaptoethanol - chemistry; Metal Nanoparticles; Serum Albumin, Bovine - chemistry
• ISSN: 1364-5528
• DOI: 10.1039/c2an16270a

We have developed a simple, low-cost, paper-based probe for the selective colorimetric detection of copper ions (Cu(2+)) in aqueous solutions. The bovine serum albumin (BSA)-modified 13.3-nm Au nanoparticle (BSA-Au NP) probe was designed to detect Cu(2+) ions using lead ions (Pb(2+)) and 2-mercaptoethanol (2-ME) as leaching agents in a glycine-NaOH (pH 12.0) solution. In addition, a nitrocellulose membrane (NCM) was used to trap the BSA-Au NPs, leading to the preparation of a nanocomposite film consisting of a BSA-Au NP-decorated membrane (BSA-Au NPs/NCM). The BSA-Au NPs probe operates on the principle that Cu deposition on the surface of the BSA-Au NPs inhibits their leaching ability, which is accelerated by Pb(2+) ions in the presence of 2-ME. Under optimal solution conditions (5 mM glycine-NaOH (pH 12.0), Pb(2+) (50 μM), and 2-ME (1.0 M)), the Pb(2+)/2-ME-BSA-Au NPs/NCM enabled the detection of Cu(2+) at nanomolar concentrations in aqueous solutions by the naked eye with high selectivity (at least 100-fold over other metal ions). In addition, this cost-effective probe allowed for the rapid and simple determination of Cu(2+) ions in not only natural water samples but also in a complex biological sample (in this case, blood sample).