Preparation Of Functional Hyperbranched Complexes And Their Application In Electrochemical Sensing

The incidence of malignant tumors or cancer diseases tend to younger age with the increasing pace of life and high environmental pollution problems,furthermore,most of the disease has been diagnosed to the medium or advanced-stage,which missed the best treatment period.Therefore,early diagnosis of diseases,especially malignancies,is great significance for clinical pathologic analysis,alleviating patient sufferings,prolonging life and improving the cure rate of cancer.Due to the excellent properties,such as good specificity,high sensitivity,rapid detection,nano-electrochemical biosensors has been widely used in the detection of tumor markers.However,numerous biological components and different concentration changing caused by different diseases increase the detecting difficulty for target analytes.Therefore,in order to improve the immobilization efficiency of biomolecules,maintain biological activity while providing outstanding electron transport interface,we take advantages of biosensing technology,nanotechnology and electrochemical technology to focus on the development of nano-electrochemical biosensors,which can be applied to different detection environment.The main contents can be concluded as follows:1.The end-group of hyperbranched polyester(HBPE)was modified by simple chemical reaction to prepare the biomimetic enzyme(HBPE-AMPA-Mn2+NPs),which were used to developed an electrochemical biaosensor for superoxide anion radical(O2·-)detection.More details in preparing of HBPE-AMPA-Mn2+NPs and the fabricating of biosensor were presented.And the electrochemical behaviors of the freshly electrochemical biaosensor were studied.The results indicated that the proposed biosensor exhibited excellent electrochemical properties for O2·-detection with a low detection limit of 0.026 ?M(S/N-3),wide linear range(0.79-16.6?M).At the same time,good anti-interference ability,stability and accuracy of the biosensor were obtained.Finally,the prepared biosensor was further used for in vitro real-time detection of O2·-released by living cells,resulted showed that 105 cells could release about 0.108 nmol O2·-2.A novel label-free immunosensor baxsed on hyperbranched polyester nanoparticles with nitrite groups(HBPE-NO2),which were synthesized through a simple one-step chemical reaction,was first developed for specific detection of a-fetoprotein(AFP),the tumor marker for liver cancer.The obtained HBPE-NO2 NPs were characterized by the proton nuclear magnetic resonance spectroscopy(1H-NMR),X-ray photoelectron spectroscopy(XPS)and X-ray diffraction(XRD).And the fabricated process of immunosensor was investigated by attenuated total reflection Fourier-transform infrared spectra(ATR-FTIR),static water contact angles,scanning electron microscope(SEM),cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS).The electrochemical performances of the AFP immunosensor were studied.Results indicated the prepared HBPE-NO2-modified immunosensor showed excellent electrochemical properties and satisfactory accuracy for the detection of AFP of the real clinical samples that attributed to the properties of the HBPE-NO2 NPs,which had nanosized structure to increase the specific surface area and unique chemical reactivity for loading capacity of protein molecules.Construction of biosensors using the structure and properties of hyperbranched molecules will offer ideal electrode substrates,which provided more possibilities for the design of biosensor.3.Hyperbranched polyester nanoparticles with sulfonic acid functional groups(HBPE-SO3 NPs)and positive gold colloid(Au NPs)were synthesized successfully,and then developed a label-free electrochemical aptamerbiosensor using thrombin-binding aptamer(TBA)as receptor for the measurement of thrombin in whole blood.The biocompatibility and hemocompatibility of the HBPE-SO3 NPs and aptamerbiosensor were evaluated.The indium tin oxide(ITO)electrode surface modified with HBPE-SO3 NPs was grafted with TBA,which has excellent binding affinity and selectivity for thrombin.Binding of the thrombin at the modified ITO electrode surface greatly restrained access of electrons for a redox probe of[Fe(CN)6]3-/4-.Moreover,the aptamerbiosensor could be used for detection of thrombin in whole blood,a wide detection range(2.69 pM-26.9?M)and a detection limit of 0.90 fM were demonstrated.The good anti-interference,stability and repeatability of this aptamer biosensor were also proved.4.The homogeneous ZnO nanorods were prepared on the ITO surface by one-step hydrothermal method,which were microscale and hydrophobic.And then the mutifuctional HBPE-NO2 NPs were fabricated on the ZnO nanorods surface by nucleophilic substitution reaction and electrostatic interaction.A new electrochemical cytosensor was prepared based on the specific recognition of sialic acid(SA)on the living cells and sambucus nigra agglutinin(SNA)on the GCE surface.More details in fabricating of cytosensor were presented as well as the biocompatibility and cytotoxicity assay(MTT).Using human lung adenocarcinoma cells(A549)as model,the cytosensor could response down to 10 cells/mL-1 with a linear calibration range from 1.73×101?1.73×107 cells/mL.