Determination of Co2+ ions in blood samples: A multi-way sensing based on NH2-rich carbon quantum dots
J.J.P. Oliveira, Samuel Veloso Carneiro, A.A.C. Cruz, L.M.U.D. Fechine, S. Michea, Renato Altobelli Antunes, Manoel Lourenço Alves Neto, Thiago Alves Moura, Carlos L. César, Hernandes F. Carvalho, Alexandre Rocha Paschoal, G.S. Lopes, Rafael M. Freire, Pierre Basílio Almeida Fechine
Abstract
Multiple forms of detecting Co 2+ are reported in this work to quantify these ions in real blood plasma samples. Carbon Quantum Dots (CQDs) were used as a fluorescent nanoprobe . The CQDs were obtained from a bottom-up approach using a hydrothermal method and choline chloride and branched poly(ethyleneimine) as precursor molecules. Several spectroscopic and structural characterizations were performed. The efficient fluorescence quenching of CQDs related to the Co 2+ ion was used for the detection of the analyte, generating a sensing strategy with a limit of detection (LOD) of 0.98 μmol L −1 . Furthermore, the interaction between the Co 2+ ion with the CQDs resulted in the color change of the solution from colorless to pale yellow. Thus, a colorimetric Co 2+ sensor was also developed, since there was an absorption band at 315 nm attributed to the formation of the complex CQD + Co 2+ . The colorimetric method showed an excellent sensitivity to Co 2+ , with a LOD of 3.01 μmol L −1 . In addition, Principal Component Analysis (PCA) together with Linear Discriminant Analysis (LDA) were used successfully to distinguish different concentrations of Co 2+ and different interfering ions present in the solution. Finally, a real sample of blood plasma was properly treated and doped with different concentrations of Co 2+ , which was successfully quantified via fluorescent method. Therefore, the CQDs obtained in this work are a powerful and versatile Co 2+ detection tool.