Visual detection of copper(ii) ions in blood samples by controlling the leaching of protein-capped gold nanoparticlesElectronic supplementary information (ESI) available: Fig. S1S5. See DOI: 10.1039/c2an16270a

• Main Authors: Lee, Yen-Fei, Deng, Ting-Wei, Chiu, Wei-Jane, Wei, Tsao-Yen, Roy, Prathik, Huang, Chih-Ching
• Format: Article
• Language: English
• ISSN: 0003-2654; 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 glycineNaOH (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 glycineNaOH (pH 12.0), Pb 2+ (50 M), and 2-ME (1.0 M)), the Pb 2+ /2-MEBSA-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). The BSA-Au NPs-modified nitrocellulose membrane (BSA-Au NPs/NCM) probe can selectively detect copper ions (Cu 2+ ) by determining the reduction in the leaching of Au NPs resulting from the deposition of Cu 2+ on the surface of the NPs in the presence of leaching agents Pb 2+ and 2-ME.