金纳米粒子-壳聚糖-石墨烯纳米复合材料的制备及其在生物电化学中的应用

Preparation and Bioelectrochemical Application of Gold Nanoparticles-Chitosan-Graphene Nanomaterials

通过共价键作用和原位还原法制备了金纳米粒子/壳聚糖-石墨烯纳米复合材料(AuNPs/Chit-GP).利用FT-IR,UV-vis,TEM以及XRD对所合成的纳米复合物的结构和形貌进行了表征.AuNPs/Chit-GP呈现明显的正电荷,因此可通过静电相互作用固载葡萄糖氧化酶(GOD),并构建GOD/AuNPs/Chit-GP/GC修饰电极.该修饰电极不仅可成功地实现GOD与电极间的直接电子转移,还对葡萄糖表现出良好的催化性能.实验结果表明,其催化的线性范围为2.1～5.7μmol/L,检出限为0.7μmol/L,灵敏度为79.71 mA cm-2 mM-1.这种集金属纳米粒子、生物相容性高分子以及石墨烯为一体的纳米复合物的构筑为无媒介体的电化学生物传感器的研究提供了一个良好的平台.

Based on the covalent modification and in-situ reduction,chitosan and gold nanoparticles were integrated with graphene to form a novel gold nanoparticles/chitosan-graphene（AuNPs/Chit-GP） nanocomposite.The process of the fabrication of AuNPs/Chit-GP nanocomposite consisted of the following steps.Firstly,carboxyl-GP was prepared based on the reduction and modification of graphene oxide（GO）.Thereafter,chitosan was covalently functionalized onto graphene nanosheet to fabricate Chit-GP.The AuNPs/Chit-GP nanocomposite was finally synthesized by the in-situ reduction of HAuCl4in the presence of Chit-GP.Fourier transform infrared（FT-IR） spectra,ultraviolet-visible（UV-vis） absorption spectra,transmission electron microscopy（TEM） and X-ray diffraction（XRD） were utilized to characterize structure and morphology of the as synthesized nanocomposite.Because of the surface functionalization of chitosan,the composite exhibited positive charge.In that case,the negatively charged glucose oxidase（GOD） could further immobilize onto AuNPs/Chit-GP via electrostatic interaction under mild experimental condition.With the advantages of graphene,Au nanoparticles and chitosan,AuNPs/Chit-GP can offer a conductive and favorable microenvironment for the immobilized GOD to achieve direct electrochemistry.The direct electron transfer（DET） reaction of the immoblized GOD was studied by cyclic voltammetry in 0.1 mol/L phosphate buffer solution（PBS,pH 7.4）.A pair of well-defined,quasi-reversible redox peaks of GOD were obtained at GOD/AuNPs/Chit-GP/GC modified electrode,with a formal potential（vs.Ag/AgCl） being-0.44 V.Moreover,the as fabricated GOD/AuNPs/Chit-GP/GC modified electrode exhibited excellent catalytic performance towards glucose.The electrocatalytic response of GOD/AuNPs/Chit-GP/GC modified electrode altered linearly with the glucose concentration ranging from 2.1 to 5.7 μmol/L.The detection limit and the sensitivity of the enzyme electrode were 0.7 μmol/L（S/N=3） and 79.71 mA cm-2 mM-1,respectively.Because of the biocompability of the AuNPs/Chit-GP,GOD/AuNPs/Chit-GP/GC modified electrode also exhibited acceptable reproducibility and excellent stability.Therefore,such a novel nanocomposite composed of metal nanoparticles,biocompatible macromolecules and graphene provides an efficient platform for the development of mediator-free electrochemical biosensors.