Application Of Functional Nucleic Acids In Combination With Chemometric Methods To The Quantification Of Heavy Metal Ions

Functional nucleic acids including DNAzyme,aptamer and aptazyme are a class of nucleic acid molecules with specific biological functions far beyond the genetic function of traditional nucleic acids.Functional nucleic acid has been widely used in area of biosensing technology such as the detection of protein,metal ions and small molecules,et al.The sensing methods based on functional nucleic acid for determination of metal ions have the advantages of simplicity,rapidity,high sensitivity and good specificity.However,most of the previous work has been mainly concerned with theories rather than their practical applications.Further research is still required to apply these techniques to the quantative analysis of complex real-world samples.In this thesis,some novel multivariate calibration methods developed by our research group were combined with sensing technologies based on functional nucleic acids to realize the rapid and accurate detection of metal ions in real-world samples.In chapter 2 of this thesis,a novel calibration strategy for quantitative circular dichroism(CD)spectroscopic analysis of real-world samples based on molecular probe technique was proposed as follows:1)Firstly,the background CD spectrum of the real-world sample to be analyzed is recorded before the addition of the molecular probe;2)the CD spectra of both the standard samples and cosmetic sample recorded after the addition of the molecular probe are projected onto a projection space orthogonal to the space spanned by the background CD spectrum of the real-world sample,3)subsequently,a multivariate calibration model is built and optimized based on the transformed CD spectra of the standard samples,and then applied to quantitative analysis of the transformed CD spectrum of the real-world sample.The proposed calibration strategy in combination with a G-quadruplex DNAzyme(e.g.PS2.M)has been succefully applied to the accurate quantification of Pb2+ in cosmetic samples using CD spectroscopy.Ag+ can react with cytosine(C)to form C-Ag+-C structure which will destroy the structure of fluorescent dye ThT-G-quadruplex complex and hence qunench the fuorescence of ThT.In chapter 3,a generalized ratiometric fluorescent probe for quantification of Ag+ was designed by combing ThT-G-quadruplex complex with an internal standard(i.e.,butylated rhodamine B).With the application of quantitative fluorescence model for generalized wavelength-ratiometric probes(QFMGRP)developed by our research group,the constructed generalized ratiometric fluorescent probe realized accurate quantitative analysis of Ag+ in environmental water samples.In chapter 4,a label-free ratiometric fluorescence sensor for quantification of Pb2+ was designed based on the interaction between the G-rich sequence AGRO100 and the fluorescent dye ThT and NMM,The label-free ratiometric fluorescence sensor combined with QFM was tentatviely utilized to quantify Pb2+ in soil samples.The quantification results of the proposed method were consistent with those obtained by atomic absorption spectrometry.