Synthesis Of Peptides And Their Applications In The Detection Of Metal Ions

Over the past decade,within the scope of the world,heavy metals in the environment pollution is more and more serious,has aroused the attention of the governments and the environmental protection organization,become after the issue of climate change and a global environmental problem.The detection research of metal ion has a great significance for life science,environmental science,and medicine.Therefore,the development of some new methods of detection of heavy metal ions analysis is very important.Protein is constitute of peptide fragments.Peptides as small molecular weight protein,both has the general characteristics of protein,but also has its unique physiological function,so the function of peptides is causing the attention of the world today.The research of peptide began to become a hot topic in the scientists to study.Peptides can interact with metal ions,the advantages become the most outstanding sensor in the detection of metal ion.Based on metal ions and polypeptide,we studied the interaction between them in the application of metal ion detection.In this paper,based on the metal ions and the interaction of polypeptide,design and synthesis of the four peptides based chemical probes,metal ions was studied respectively and the interaction between them,for the design of chemical sensors provides a theoretical basis.The main contents are as follows: 1.The peptide colorimetric probe for the specific detection of Hg²⁺A new heptapeptide Cys-Pro-Gly-Cys-Pro-Gly-Cys-CONH2（P7）has been prepared via Fmoc solid-phase peptide synthesis（SPPS）and High Performance Liquid Chromatography（HPLC）and characterized by Mass Spectrometry（MS）.The interactions of P7 with metal ions were also investigated by spectroscopy,showing that P7 has highly selective binding affinity to Hg（II）.By using this specific character,a simple,rapid and sensitive detection method for Hg（II）has been developed.When the mixture solution of P7 and Hg（II）was added into colloidal gold nanoparticles（GNP）,the color of GNP remained unchanged.On the contrary,the color of GNP changed from red to blue when the mixture solutions of P7 and other metal ions were added.LOD is 0.10 μmol×L-1.2.The synthesis of ferrocene polypeptide Fc-CPPCG and electrochemical researchThe ferrocene-peptide Fc-CPPCG（Fc-P5）was synthesized by Fomc-SPPS.The electrochemical characterization of glassy carbon electrode and the glassy carbon electrode modified by Fc-CPPCG was used cyclic voltammetry（CV）,linear sweep voltammetry（LSV）and electrochemical impedance spectroscopy（EIS）.The results show that it has good electrochemical performance.And then study the electrochemical response of the glassy carbon electrode modified by Fc-CPPCG for the metal ions,i.e.it selective effects of metal ions.The results showed that the addition of Hg²⁺ make the current peak of Fc-CPPCG greatly reduced.electrochemical impedance was also significantly reduced.Those changes prove that the specific reaction of Fc-P5 and Hg²⁺.The reduction of current peak is due to the reaction of Hg²⁺ with the Cys of Fc-P5.The reaction makes the microenvironment of ferrocene group changes,gradually reduce the ferrocene electron density.The decrease of impedance is due to the complexing reaction of Hg²⁺ and Cys of Fc-P5,which makes peptides from the electrode surface free.The Blocking effect of electron transfer of [Fe（CN）6]3-/4-and electrode was reduced,promoted the electron transfer of [Fe（CN）6]3-/4-and the electrode.3.The investigation of a high selectivity ratiometric fluorescent chemosensor for Zn²⁺A series of fluorescent probe Dansyl–HERYKW,Dansyl–HENRKW and Dansyl–HENRYKW was synthesized.The interaction of peptides and different metal ions was investigated by fluorescence spectrum.Results show that Dansyl-HERYKW and Dansyl-HENRKW has no special selectivity of metal ions,the Dansyl–HENRYKW has special selectivity of Zn²⁺.The addition of Zn²⁺makes the fluorescence intensity of Dansyl-HENRYKW at 515 nm enhanced.And other metal ions and anions has no effect on the reaction system,D-P7 interact with Zn²⁺ bonding ratio is 2:1,the binding constant is1.8 × 1011 L2×mol-2,the limit of detection is 0.012 μmol×L-1.4.Synthesis of CPPC and CPPCGG and the study on the the adsorption for mercury by peptide resinOn the basis of the principle of the reaction of peptides and metal ions,two similar polypeptides CPPC（P4）and CPPCGG（P6）were designed and synthesized.We studied selective function of them with metal ions by UV-Vis.The results showed that the two peptides had strong selectivity to Hg²⁺.Then,we nvestigate the adsorption of peptide resin for Hg²⁺.The results of atomic fluorescence spectroscopy found that the adsorption capacity of two kinds of peptide resin（R-P4 and R-P6）for Hg²⁺ were 96 ng/g and 60 ng/g,the optimum pH for adsorption were 3.0 and 5.0,respectively.