Electrochemical Chiral Sensor Based On Proteins And Amino Acids Derivatives

Chirality is an essential property of nature and closely related with life. In nature,many biomolecules are chiral, such as DNA, amino acids, polysaccharides enzymes,and proteins. Chiral materials have attract much attention and widely used in life science, medicine and pharamaceutical science, food science, environment science and materials and information science. Especially for chiral drugs, the different configurations of drugs may display obvious discrepancies in terms of bioactivity,toxicity, mechanisms of rate and the process. Therefore, it is important to develop methods for chiral recognition of chiral drugs. There are many methods for chiral recognition, in which the electrochemical techniques gain widely application in analytical chemistry because of the advantages including easy operation, rapid response,high sensitivity and lower cost. This paper applied proteins amino acids derivatives and its nanocomposites to develop electrochemical chiral sensors. The main work are included as follows:1. A simple chiral sensing platform for chiral recognition of quinine(QN) and quinidine(QD) was fabricated via incubating bovine serum albumin(BSA) on the electrodepositive gold nanoparticles(AuNPs) modified glass carbon electrode(GCE).Scanning Electron Microscopy(SEM) was employed to characterize the surface morphology of AuNPs and the sensing platform; differential pulse voltammerty(DPV)and ultraviolet-visible spectroscopy(UV-Vis) were used to assess the interactions between BSA and QN/QD; the experimental conditions, such as concentration of target analyte and incubation time were also discussed. The results displayed that after the platform interacted with QN and QD, a larger signal was obtained from QD when the concentration less than 0.5 mmol·L-1, while a larger electrochemical signal was achieved from QN when the concentration of the enantiomers increased to 0.5mmol·L-1.2. The solution of HAuCl4(1%) and BSA were used to prepare the chiral nanocomposite of Au@BSA. A biosensing interface toward the recognition ofpropranolol(PRO) was developed using Au@BSA modified gold electrode. The nanocomposite was characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), ultraviolet-visible(UV-vis) and energy dispersive X-ray(EDX); Cyclic voltammetry(CV) was applied to study the electrochemical behaviors of different modified electrodes; The interactions between the sensing platform and PRO enantiomers were explored via DPV and atomic force microscopy(AFM); The influence of concentration of target analyte, pH of target analyte solution and incubation time on enantioselective recognition were also investigated. To gain more information about the role of gold nanoparticles(AuNPs) and bovine serum albumin(BSA) in chiral recognition of PRO enantiomers, the interface fabricated via AuNPs or BSA was also utilized to interact with PRO enantiomers, and no obvious signal discrepancy was obtained. The results indicated that only Au@BSA could be employed to the enantioselective recognition of PRO enantiomers and a larger electrochemical response was obtained from S-PRO.3. Silver-graphene oxide(Ag-GO) was successfully prepared and modified on the surface of GCE, L-N-isobutyryl-cysteine as chiral selector was modified on the surface of Ag-GO via the bond of Ag-N to construct a reagentless chiral sensing platform for chiral recognition of naproxen(Nap). The abundant oxygenated groups on GO sheets could offer an excellent environment for the loading of various nanoparticles, silver nanoparticles(AgNPs) had strong conductivity and electroactivity. Therefore, the combination of GO and AgNPs not only preserved the favorable properties of GO and AgNPs, such as good water-solubility, conductivity and electroactivity, but also acted as redox probe and signal amplifier. In this study the Energy Dispersive X-ray(EDX),ultraviolet-visible(UV-Vis) spectrometry and scanning electron microscopy(SEM)were used to characterize the morphologies and structure of Ag-GO; Cyclic voltammetry(CV) was applied to study the electrochemical behaviors of the modified electrodes; At the same time CV and SEM were also used to study the steroselective interactions between chiral platform and Nap enantiomers. The results showed that larger electrochemical response was obtained from S-Nap.