Metal Coordination Compounds-based Nanomaterials:Application Into Photo/electrochemical Biosensors

Metal coordination compound,a complex formed by the coordination of the ligand with the metal ion through the coordination bond.Coordination polymers(CPs),as a kind of crystal material,which is composed of the transition metal ion or ion cluster unit and the organic ligand self-assembled by the coordination interaction.CPs form an infinite,one-dimensional,two-dimensional or three-dimensional infinite network structure in space.Due to the diverse structures and excellent properties,as functional materials,CPs based materials have shown very attractive application prospect in gas adsorption,ion exchange,separation,selective catalysis,magnetic materials,optoelectronic materials and new semiconductor material etc.In this dissertation,with the design and synthesis of photo-electrochemical active CPs,a series of CPs based electrochemical or photo-electrochemical biological system were developed.The photo-electrochemical mechanisms of CPs were investigated and the photo-electrochemical analysis conditions were optimized.A variety of biological sensing systems were constructed with the combination of micro and nanotechnology,morphology and spectroscopy,and chemical biology.The dissertation is mainly focused on the following five parts:1.Pyrocatechol violet-assisted in situ growth of copper nanoparticles on carbon nanotubes:the synergic effect for electrochemical sensing of hydrogen peroxideFor the first time,copper nanoparticles(CuNPs)were formed by in situ electrochemical reduction of the chelated copper ions on the electrode based on pyrocatechol violet(PCV)and single walled carbon nanotubes(SWCNTs).The electrodeposited PCV used as chelating agent for copper ions as well as the redox mediator during the followed electrocatalysis of H2O2.Due to the remarkable synergic effect of SWCNTs/PCV/CuNPs,the modified electrode possesses the enhanced analytical performance for non-enzymatic detection of H2O2 at-0.2 V vs.SCE with the enlarged linear range from 2×10-6 M to 1.2×10-2 M.In addition,the morphology and chemical composition of SWCNTs/PCV/CuNPs were investigated by atomic force microscope(AFM)and X-ray photoelectron spectroscopy(XPS),respectively.2.Sequential electro-deposition of highly stable Cu-Fe Prussian blue coordination polymers at indium tin oxide electrode:characterization and the enhanced sensing applicationCopper hexacyanoferrate(CuHCF),a Prussian blue-type coordination polymer was synthesized to modify indium tin oxide(ITO)electrode using the facile derivatization of the pre-electrodeposited metallic copper in a solution containing hexacyanoferrate(III)for the first time.The obtained ITO/CuHCF possesses a typical surface-confined behavior with a pair of stable and symmetrical redox signal at around 0.65 V vs.SCE at scan rate of 10 mV s-1.Moreover,the ITO/CuHCF exhibits an enhanced analytical performance for amperometric detection of captopril with an enlarged linear range from 6.0×10-7 to 5.3×10-4 mol L-1,a low detection limit(0.43 μmol L-1)and a high sensitivity(68.86 μA mmol L-1 cm-2).This proposed sensor has been successfully applied to determine captopril in commercial tablet and urine samples.3.Magnetic zirconium hexacyanoferrate(Ⅱ)nanoparticle as tracing tag for electrochemical DNA assayNovel multifunctional magnetic zirconium hexacyanoferrate nanoparticles(ZrHCF@MNPs)were prepared,which consisted of magnetic beads(MBs)inner core and zirconium hexacyanoferrate(Ⅱ)(ZrHCF)outer shell.As an artificial peroxidase,the ZrHCF@MNPs exhibited remarkable electrocatalytic properties in the reduction of H2O2 at 0.2 V vs saturated calomel electrode(SCE).On the basis of the bonding interaction between Zr(Ⅳ)of the shell ZrHCF framework and phosphonate groups,the 5’-phosphorylated ssDNA probes with a consecutive stretch of guanines as a spacer could be incorporated in ZrHCF@MNPs easily.Thus,DNA-grafted ZrHCF@MNPs could be simply obtained by magnetic separation.The prepared nanoelectrocatalyst was further used as signal nanoprobe for the ultrasensitive electrochemical DNA assay.Under optimal conditions,the proposed biosensor presents high sensitivity for detecting target DNA with a linear range from 1.0 fM to 1.0 nM and a low detection limit of 0.43 fM.Moreover,it exhibits good performance with excellent selectivity,high stability,and acceptable fabrication reproducibility.4.Zirconium-metalloporphyrin frameworks as a three-in-one platform for electrochemiluminescence protein kinase activity assayA Zr-based metal-organic framework with zinc tetrakis(carboxyphenyl)-porphyrin(ZnTCPP)groups(MOF-525-Zn)was utilized to develop a novel electrochemiluminescence(ECL)biosensor for highly sensitive protein kinase activity assay.In this work,in terms of ECL measurements and cyclic voltammetry,the cathodic ECL behaviors of MOF-525-Zn in aqueous media were thoroughly investigated for the first time.The photoelectric active groups ZnTCPP on the MOF-525-Zn frameworks could promote the generation of singlet oxygen(1O2)via a series of electrochemical and chemical reactions,resulting in a strong and stable red irradiation at 634 nm.Additionally,the surfactant tetraoctylammonium bromide(TOAB)further facilitated dissolved oxygen to interact with the active sites ZnTCPP of MOF-525-Zn.Furthermore,the inorganic Zr-O clusters of MOF-525-Zn were simultaneously served as the recognition sites of phosphate groups.And then,an ultrasensitive ECL sensor was proposed for protein kinase A(PKA)activity detection with a linear range from 0.01 to 20 U mL-1 and a sensitive detection limit of 0.005 U mL-1.This biosensor can also be applied for quantitative kinase inhibitor screening.Finally,it exhibits good performance with high stability and acceptable fabrication reproducibility,which provide a valuable application prospect for clinic diagnostics and therapeutics.5.Zirconium-based porphyrinic metal-organic framework(PCN-222):enhanced photoelectrochemical response and its application for label-free phosphoprotein detectionA simple and rapid photoelectrochemical(PEC)sensor was developed for the label-free detection of a phosphoprotein(a-casein)based on a zirconium based porphyrinic metal-organic framework(MOF),PCN-222,which exhibited an enhanced photocurrent response toward dopamine under the 02-saturated aqueous media.In this work,in terms of PEC measurements and cyclic voltammetry,the PEC behaviors of PCN-222 in aqueous media were thoroughly investigated for the first time.Additionally,in the virtue of the steric hindrance effect from the coordination of the phosphate groups and inorganic Zr-O clusters as binding sites in PCN-222,this biosensor showed high sensitivity for detecting a-casein and the limit of detection(LOD)was estimated to be 0.13 μg mL-1.Moreover,the proposed method provides a promising platform for clinic diagnostic and therapeutics.