Construction Of Several New Nanosensors And Their Applications In Bioanalysis

With the development of information technology and bioengineering technology,biosensors have shown a powerful vitality.Nowadays,the developed countries have considered biosensors as the key technology of the 21 st century.Compared with the traditional and complex analysis methods,the new biosensors have many advantages containing the high selectivity,high sensitivity,rapidity,miniaturization and low cost.They are widely used not only in environmental pollutant monitoring,food safety,medical field,but also in space life science,military,aerospace remote sensing and so on.However,with the increasingly diverse and complex for the target analytes,biosensing methods and analytical techniques are also faced new demands and challenges.In recent years,nanomaterials have become a hot research object for scientific researchers.Nano-scale material particles have different properties from conventional substances,and some even have undergone qualitative changes.Due to the specificity of nano-scale material,nanomaterials have attracted people's extensive attention.Functionalized nanomaterials exhibit many advantages,such as large surface area,high catalytic activity,good biocompatibility,and so on,which can be used as a sensor for biosensor construction.These provide new insight and design idea for the new-type biosensors construction.Based on a large number of related literatures,this paper mainly studies the application of several new functional nanomaterials in biosensor.The main pionts of this thesis are summarized as follow:Chapter One: We described the concepts,characteristics,classification and application of biosensors and nanomaterials.Chapter Two: In this study,we developed a novel,facile and ultra-sensitive fluorescence assay for the determination of tumor invasive biomarker ?-glucuronidase?GLU?based on the inner filter effect?IFE?.The nitrogen-doped carbon quantum dots?N-CQDs?with green photoluminescence were employed as the fluorophore in IFE,and 4-nitrophenyl-?-D-glucuronide?PNPG?was used to act as GLU substrate,and GLU catalytic product?p-nitrophenol?PNP??was capable of acting as the robust absorber in IFE to turn off the fluorescence of N-CQDs due to the complementary overlap between the absorption of PNP and the excitation of N-CQDs.Thus,signal of GLU activity could be recorded by the fluorescence intensity of N-CQDs.This method was also successfully applied to the analysis of serum samples and the inhibitor screening from natural product.Chapter Three: Herein,we reported the design and application of a specific ratiometric fluorescent probe,which contained carbon quantum dots?CDs?as sensing signal and Rhodamine B?RhB?as reference,for highly sensitive detection of mercury ions(Hg²⁺and glutathione?GSH?.The obtained nanosensor showed characteristic fluorescence emissions of CDs and RhB under a single excitation wavelength.The functional CDs were first synthesized in our laboratory according to a one-pot pyrolysis process of sodium citrate with histidine.In the presence of Hg⁽2+,only the fluorescence of CDs was quenched due to electron transfer between Hg⁽2+ and functional groups on the surface of CDs.Subsequently,the fluorescence of CDs–Hg⁽2+ system was recovered gradually with the addition of GSH due to their stronger affinity with Hg⁽2+,which could effectively exclude numerous background interferences.This method has been successfully applied to oxidative stress model investigation.Chapter Four: In this study,based on the inhibitory effect of pesticide residues on alkaline phosphatase,the double amplification strategy of alkaline phosphatase?ALP?combined with Ag0-Ag₃PO₄ nanometer enzyme was successfully applied to the ultra-sensitive colorimetric detection of pesticide residues in vegetables.In the experiment,Ag+ can be reduced by ascorbic acid?AA?to Ag nanoparticles.And then Ag nanoparticles deposited on the surface of diamond-shaped dodecahedron Ag₃PO₄ to form the Ag0-Ag₃PO₄ nanoenzyme,which greatly improved the photocatalysis activity.The TMB was subsequently oxidized to oxTMB.By measuring the absorbance of ox TMB,the activity of ALP can be calculated and realized the quantitative detection of pesticide residues.