Diphenylalanine Self-assembly And Its Application In Electrochemical Enzyme Biosensor

Bioactive molecules has been the popular building blocks of molecular self-assembly tomanufacture new nano-materials.Among them,because of wide variety,different property andfunction, the oligopeptides have been gradually becoming the first choice in the research ofself-assembled nano-materials.Moreover,the straightforward and simple production,easilymodified chemically and functionalized biologically characters open up a wide range ofpossible applications prospects for peptide nano-materials in biosensing,drug delivery,tissueengineering and so on.In this research,the diphenylalanine peptide （L-Phe-L-Phe,FF） isemployed as the building blocks.Firstly,We investigate the morphology controllable changesof FF self-assembly induced by acetonitrile,and propose a new self-assemblymechanism.Then,an electrochemical biosensor based on the aforementioned FF self-assemblyproduct is constructed to examine the possibility of its application in electrochemical enzymesensor.The main research contents are as follows:（1）This research manipulates FF into ordered microcrystal with interesting dandelion-like morphology in the organic solvent acetonitrile. The morphology transition like fan-opening is controlled by changing the FF’s concentration. And the FF local concentration is adecisional role for forming cole and the extending growth range of the nanowires around thecole. Dandelion-like microcrystal is charactered by fluorescence emissionspectrum,ultraviolet-visible absorption spectrum, fourier transform infrared spectrum,circular dichroism spectrum, X-ray diffraction and so on. Experimental results show that anti-parallel β-sheet and π-π stacking of the aromatic residues have a crucial role to construct andstabilize the self-assembled structure. And on this basis, a new self-assembled mechanism ofFF is proposed.（2）This research fabricates an electrochemical biosensor based on self-assembleddiphenylalanine dandelion-like microcrystal. The horse radish peroxidase is covalently boundon the microcrystal via glutaraldehyde and protected by Nafion as embedding medium.Experimental results show that the biosensor displays excellent bioelectrocatalytic abilitytoward the reduction of hydrogen peroxide（H2O2）with a linear response over a concentrationrange from5.0×10^-7mol/L to6.0×10^-4mol/L．the detection limit is2.5×10^-7mol/L（S/N=3）.The Michaelis-Menten constant of the immobilized enzyme is calculated to be0.83mmol/Lfor H2O2, which indicates that the enzyme maintains excellent enzymatic activity and has highaffinity to H2O2.This method using modified electrode of oligopeptides self-assembledstructures can provide an new idea for fabricating electrochemical biosensor.