Pan Li,Jiawei Li,Minghong Bian,Danqun Huo,Changjun Hou,Ping Yang,Suyi Zhang,Caihong Shen,Mei Yang
In this paper, we developed a label-free fluorescence assay employing BSA-Au NCs, S2O32−, and 2-ME for the highly selective and sensitive detection of Pb2+ in sorghum, river water and tap water. When the BSA-Au NCs reacted with S2O32− in solution, Au(S2O3)23− complexes were formed immediately on the surfaces of BSA-Au NCs. After adding Pb2+ and 2-ME, the BSA-Au NCs rapidly dissolved to form Au–S complexes. As a result, the fluorescence intensity decreased dramatically, allowing quantification of Pb2+ in the aqueous solution. This reaction is highly specific under optimal detection conditions. A good linear relationship between the fluorescence intensity and the concentrations of Pb2+ could be obtained in the range of 10 to 1000 nM (R2 = 0.9910), with a detection limit (LOD; S/N ratio = 3) down to 1.043 nM. Significantly, compared with other studies, we greatly shortened the reaction time by substantial improvements in materials. On the basis of the above-mentioned work, we successfully immobilized S2O32− modified BSA-Au NCs on wax-printed papers to achieve the purpose of simple and real-time field monitoring of Pb2+. We picked up R-values (the red value of the RGB color model) from captured flurescence images under UV light (365 nm) and acquired a linear correlation between R-values and Pb2+ concentrations. This linear correlation exhibits the great potential of this approach. The proposed probe also showed satisfactory selectivity as well as excellent reproducibility. Multiple real sample experiments showed the tremendous prospect of this method, as well.
Cu2+ plays an important role in various fundamental physiological processes in organisms. Although Cu2+ probes have been developed, little research has focused on using a direct redox route to quench fluorescence for Cu2+ detection. Herein, a simple, label-free, cost-effective, and sensitive fluorescence method has been developed for Cu2+ detection. In the absence of Cu2+ and presence of NH3+ and SCN−, H2O2 was employed as an oxidant to corrode BSA–Au NCs, resulting in the disappearance of fluorescence. In contrast, in the presence of Cu2+, red fluorescence was maintained because Cu(NH3)62+ can decompose H2O2. Under optimal conditions, good linear correlation between the fluorescent response and Cu2+ concentrations ranging from 5 to 1250 nM was obtained (R2 = 0.9938). Furthermore, this monitoring method has successfully been applied to real urine, tap water, and sorghum extract samples, demonstrating the potential for field applications. Based on this work, we successfully immobilized BSA–Au NCs on wax-printed paper to accomplish real-time field Cu2+ detection. Fluorescence images were captured under UV light (365 nm), and R-values (red value of RGB color model) were analyzed. The obtained linear relationship between the R-value and the Cu2+ concentration demonstrated the potential of this approach. The developed probe also showed satisfactory selectivity and excellent reproducibility. Although previous methods required a masking agent to protect against interference from increasing Hg2+ concentration, Hg2+ and other interfering ions had a near-negligible effect on results in the present work.
危险品化学品经营许可证（带存储）