Controlling Self-assembly Of Diphenylalanine Peptide For Electrochemical Biosensor

Recently, self-assembly of phthalidyl-material has become a hot area of research on crossfields such as chemistry, biology and material science. Especially Diphenylalanine Peptide（FF） attractes the researchers’ more interest because of its easy synthesis, assembly, relativelystability and broad application prospects. Biosensor has valuable applications in environmentscience, food industry and medicine. Self-assembly of FF has huge potential for improvingthe performance of biosensor. Synthetizing Nano-and Submicron-material assisted bysurfactant have been verified as an important method which is environmental protection andcan be expanded largely. Therefore, this paper is focusing on the research of preparation ofmaterials based on controlling self-assembly of FF for biosensor. Controlled submicron fiberstructure, Broom structure and sector structure of FF are obtained by using cationic surfactantcetyl trimethyl ammonium bromide （CTAB）, anionic surfactant sodium dodecyl benzenesulfonate （SDBS） and nonionic surfactant polyvinylpyrrolidone （PVP） to intervene FFassembly process separately. Furthermore the electrochemical properties of these materials areanalyzed. Especially this paper discuss the self-assembly mechanism in submicron fiberstructure and its application in H₂O₂biosensor. The details are described as follows:（1） Fiber structure based on self-assembly of FF is achieved induced by cationicsurfactant CTAB. The control of two conditions which are humidity and molar ratio betweenCTAB and FF, on the self-assembly structure is considered. Morphology and intermolecularforces of the fiber are characterized by SEM, CD, FTIR, FL, XRD and electrochemicaltechniques. Results show that fiber diameter decreases with increasing of molar ratio betweenCTAB and FF, the most homogeneous fiber can be obtained under relative humidity of0.33.CTAB induces the self-assembly process of FF, in which β-fold secondary structure and Ï€-Ï€stacking effect have important roles. This method provides a simple and environmentallyfriendly way for preparation controlling FF Submicron fiber structure.（2） A H₂O₂biosensor based on the FF submicron fibers exhibiting excellentelectrochemical properties and biological compatibility has been devised. The results showthat under the optimum conditions that the pH is7.0, the electric potential is-0.7V, Aquantitative measurement of H₂O₂is achieved with the linear range of7.5×10^-71.4×10^-5M,and the detection limit is2.5×10^-7M. The results indicate that FF submicron fibers have greatpotential application in H₂O₂biosensor.（3） Controlled sector structure and broom structure based on self-assembly of FF areobtained using nonionic surfactant PVP and anionic surfactant SDBS separately. The controlof three conditions which are molar ratio between surfactant and FF, temperature and humidity, on the self-assembly structure are investigated. Results show that, sector structureof FF can be achieved with PVP only under the condition of mole ratio between PVP and FFrange from1:1.6to1:51.6, humidity higher than0.84as well as temperature above30℃;Radius and intersection angle of broom structure reduce with the decrease of molar ratiobetween PVP and FF. Three conditions of molar ratio between SDBS and FF, temperature andhumidity have significant impact on the broom structure based on self-assembly of FF. theoptimum conditions are that, molar ratio between SDBS and FF is1:4.3; temperature andhumidity remain at30℃and0.75respectively. This method puts forward a novel way toprepare controlled sector and broom structure of FF.