Research On Novel Biosensing Technology Based On Dextran Modified BiO_2-x Nanosheets

In recent years,life sciences have played an increasingly important role in the development of society and solving human diseases.With emergence and rapid development of nanotechnology,it has greatly enriched the further study of life sciences.Among them,nanomaterials included by nanotechnology have attracted great interest of many researchers because of their unique and excellent properties.At present,the wide application of nanomaterials effectively promotes the rapid development of biosensors.Nanobiosensors,a product of nanotechnology effective combine with bosensors,which have wide applications involving biosensing,bioimaging.In this paper,two dimensional nanomaterials,dextran modified BiO_2-x-x nanosheets were used to develop simple,pratical,highly selective nanobiosensing platforms.The main contents are described as follows:In Chapter 2,we reported a novel biosensing platform dextran modified BiO_2-x-x nanosheets based nanosensor platform for simple,highly selective detection of hydroquinone?HQ?and sulfite(SO₃^2-).Owning to the oxidase activity of the nanosheets,when 3,3',5,5'-tetramethylbenzidine?TMB?was added into solution,TMB was effectively oxidized to colored products.The products produced a strong absorbance peak at 652 nm.Because of to HQ or SO₃^2-having strong reducibility,when HQ or SO₃^2-was continuously added,HQ or SO₃^2-was respectively converted to p-benzoquinone tautomer or sulfate(SO₄^2-)and blue oxTMB turned to colorless TMB.By measuring the change of absorbance,HQ and SO₃^2-can be highly selective detected.In this chapter,we reported the intrinsic oxidase-like activity of dextran modified BiO_2-x nanosheets and exploited the capability to develop a simple,fast colorimetric method for quantitative and qualitative detection of HQ and SO₃^2-.In Chapter 3,we used intrinsic the oxidase-like activity of dextran modified BiO_2-x nanosheets,and we showed how this activity can be applied to the evaluation of the antioxidant capacity of gallic acid?GA?and the comparison of the antioxidant capacity of other antioxidants.Through the dextran modified BiO_2-x nanosheets interacting with TMB and O-phenylenediamine?OPD?,we further confirmed the oxidase-like activity of dextran modified BiO_2-x nanosheets.In the presence of the peroxidase substrate 2,2-diaza-bis?3-ethylbenzothiazole-6-sulfonic acid?diammonium salt?ABTS?,dextran modified BiO_2-x nanosheets converted ABTS into free radicals.The products produced a strong absorbance peak at 416 nm.GA,a natural food antioxidant,which has good antioxidant capacity and can effectively scavenge free radicals.When was continuously added GA,the absorbance at 416 nm clearly decreased.By measuring the change of absorbance,the antioxidant capacity of gallic acid?GA?and the antioxidant capacity of other antioxidants can be respectively evaluated and compared.In this chapter,through the effective combination of dextran modified BiO_2-x nanosheets and food antioxidants,we developed the sensing strategy which has wide prospects in food analysis.