Study On Biosensing Application Based On Host-guest Interaction Of Cucurbit[7] Uril And Pillar[5]Arene

In the middle of the twentieth century, researchers have a new understanding of supramolecular, with the macrocyclic molecules such as crown ether synthesized by Pedersen et al.. Supramolecules, which include enzyme and its substrate, some complex of crown ethers and certain metals, hormones and their receptors, existed through intermolecular forces. Host-guest interaction is typical, and the common host molecules include crown ether, cyclodextrin, cucurbiturils, pillararenes. The guests of these host molecules are different owing to their differences of properties. Host-guest interactions have a wide application in many fields, such as life science, materials science, medicine and biosensing.Glucose, as the main energy material, has an important status in the field of biology, and the detection of glucose is of great significance and application value in the food and medicine fields. Due to the advantages of simple operation, good selectivity and high sensitivity, electrochemical biosensing has been in researchers’ good graces among the means to detect glucose. From the first glucose enzyme electrode designed by Updike to the idea of no enzyme detection, electrochemical glucose biosensing has experienced three generations’ development, which now has been widely used in food analysis, fermentation control and clinical testing.DNA, as the basic genetic material, is essential to organism. To detect the specific sequences of DNA is significant in disease diagnosis, environmental monitoring and other fields. There are many methods to determine DNA, such as colorimetry, fluorescence spectroscopy, etc., but the electrochemical methods have attracted the researchers’ attention owing to their low-cost, high sensitivity and good specificity. In terms of electrochemical detection of DNA indicating hybridization, the way has been developed from the direct detection to a variety of indirect detection, as well as the signal amplification. DNA electrochemical biosensing is constantly developing and improving, which has a wide application in the field of genetic diagnostics, environmental monitoring and drug analysis.In this paper, we combine host-guest recognition and electrochemical biosensing to realize rapid and sensitive detection of glucose and DNA. A simple and stable glucose electrochemical biosensing was built using host-guest interaction to immobilize the mediator. On this basis, we construct a DNA electrochemical biosensing by combining enzyme and Au nanoparticles to implement signal amplification. The electrochemical bioanalysis based on host-guest interaction with advantages of simple, stable and workable, has a broad application prospects.This paper consists of the following four chapters.Chapter One:IntroductionIn this chapter, we firstly introduce the supermolecule, including crown ether, cyclodextrin, cucurbiturils, pillararenes, and then describe the host-guest interaction and its application in electrochemical biosensing. Secondly, we research progress about electrochemical biosensing, mainly introducing the glucose electrochemical biosensing and DNA electrochemical biosensing. The introductions include the development and application of glucose electrochemical biosensing, and the principle, immobilization method, electrochemical indication in DNA electrochemical biosensing. Meanwhile, we emphatically review the application of electrochemical DNA biosensing in gene diagnosis,etc. At last, we point out the purpose and significance of the dissertation.Chapter Two:Glucose electrochemical biosensing based on the host-guest interation of cucurbit[7]urilIn this chapter, a simple and sensitive method for glucose determination was described based on the host-guest interaction and electrochemical biosensing. The method used inclusive complex of cucurbit[7]uril and ferrocenemonocarboxylic acid to immobilize the mediator. Firstly, the mixture of cucurbit[7]uril and graphene oxide, ferrocenemonocarboxylic acid as electron transfer mediator and glucose oxidase as catalytic material were modified successively on the electrode. Under the optimized conditions, a linear response between current intensity and glucose concentrations over a range of 0.1～10 mM was obtained with a relatively low detection limit (27 μM, S/N=3). Meanwhile, this method exhibited high selectivity in the interference investigation, and the reliability and applicability in human serum samples analysis, which provides a facile and rapid detection approach in interrelated diseases diagnostic assays.Chapter three:Preliminary study of DNA electrochemical biosensing based on the host-guest interaction of cucurbit [7] urilIn this chapter, we prepared a DNA electrochemical biosensing based on the host-guest interaction and amplification technology with enzyme loading on AuNPs. Firstly, we prepared the gold nanoparticles (AuNPs) modified SH-DNA probe, and then GOD was loaded on AuNPs through the interactions between AuNPs and glucose oxidase (GOD). Double strand DNA (dsDNA) was formed using homogeneous DNA hybridization between Fc-DNA and SH-DNA with labeled AuNPs-GOD. Then ds-DNA was captured on modified electrode through the host-guest recognition between cucurbit[7]uril (CB[7]) and ferrocene (Fc). In this way, GOD would produce catalytic action and the concentrations of SH-DNA could be detected indirectly by determining the current difference of Fc before and after the catalysis in glucose solution. The electrochemical signal amplification can be realized by taking advantage of large surface area of AuNPs to load GOD and achieve catalysis.Chapter four:Study of electrochemical behavior based on the host-guest interaction between pillar[5]arene and octanediamineIn this chapter, the electrochemical behavior of the host-guest inclusion complex between the synthesized functionalized pillar[5]arene (P5A) and octanediamine (ODA) was studied. At first, P5 A was immobilized on Au electrode through gold sulfur bond, and then ODA as the guest was captured on electrode by host-guest interaction of P5A. Under the effect of EDC and NHS, electrochemical material FcCOOH was combined with ODA, which could produce electrochemical response. But the amide bond would be hydrolyzed in alkali solution, and Fc-COOH was separated away from the electrode surface, which will lead to the disappearances of the electrochemical signal. Morever, the modification of P5 A was characterized by AFM and chronocoulometry. The host-guest system can be further applied to DNA biological sensing and other fields, which has a good application prospects.