Study On Preparation And Sensing Applications Functional Metal-organic Frameworks

In this dissertation,studies were focused on the synthesis and characterization of functional metal-organic frameworks(MOFs),their chemiluminescent and fluorescent sesing applications in sensing various biomolecules or heavy metal ions,such as H2o2,glucose,ascorbic acid and mercury ions.There are seven chapters in this disertation and the main contents are listed as follows:In Chapter 1,first a general introduction of MOFs was given,and then recent advances in synthesis methods,applications were briefly reviewed.Finally,the motivation and significance of this study were described.In chapter 2,novel MOFs-based solid catalysts were synthesized byencapsulating hemin into the HKUST-1 MOF materials and applied in the chemiluminescence field with an outstanding performance.The functionalized MOFs not only maintained an excellent catalytic activity inheriting from hemin,but also could be recyclably utilized as solid mimic peroxidases in the neutral condition.The synthesized Hemin@HKUST-1 composites have been used to develop practical sensors for H22 and glucose with wide response ranges and low detection limits.It was envisioned that catalyst-functionalized MOFs for chemiluminescence sensing would have promising applications in green,selective and sensitive detection of target analytes in the future.In chapter 3,we further improved the material based on the work in chapter 2.In this section,we selected wide-pH-range stable Uio-66 MOFs as the protective container of the mimic enzyme of hemin,and evaluated the protection of hemin by Uio-66 over a wide pH range(2-12)by comparing the catalytic activities of Uio-66-encapsulated hemin(i.e.Hemin@Uio-66)and those of hemin without protection.The peroxidase-like activities of Hemin@Uio-66 as well as bare hemin in acid and alkaline media were investigated by Azino-bis(3-ethyl)benzthiazoline-6-surfonic acid(ABTS)-H2O2 and luminol-H2O2 systems,respectively.The catalytic acitivities of Hemin@Uio-66 at acid,neutrual and alkaline were all higher than those of free hemin,which might result from that the encapsulation of hemin in Uio-66 protects the active moiety from dimerization and higher affinity to H2O2(lower Km)and higher cataltyic efficicency(Kcat/Km).The obvious improvement in catalytic efficiency enabled Hemin@Uio-66 to have promising applications in construction novel selective and sensitive chemiluminescent and colorimetric biosensors.In chapter 4,we looked for applications of Hemin@Uio-66 for biochemical sensing.In order to show the advantages of Hemin@Uio-66 over other reported hemin based catalysts,such as Hemin@HKUST-1,their sensing performances were investigated and compared under the same experimental conditions.Our experimental results showed that Hemin@Uio-66 had wider response ranges and lower detection limits in the detection of H2O2.The recyclability of Hemin@Uio-66 was also better than Hemin@HKUST-1.In addition,the oxygen-related radicals generated by the catalytic decomposition of H2O2 could be inhibited by ascorbic acid,based on which a new,simple,fast and sensitive method for determination of ascorbic acid in water samples was established in the neutral condition.The linear response range was from 0.01 to 5 ?M,and detection limit(S/N = 3)was 1.2 nM.In chapter 5,novel multifunctional MOFs synthesized by encapsulating hemin,luminol and glucose oxidase into the Uio-66 materials(HLG@Uio-66)were used for chemiluminescence determination of glucose by one-step method.The as-prepared multifunctional MOFs was very stable and easily available,which might be used to develop practical sensors for glucose with wide response ranges(5-100 ?M),low detection limits(1 ?M)and time-saving(5?6 min)operation procedures.This ideal sensing material would be applied in the field of biotechnology and mgith have promising applications in green,selective and sensitive detection of target analytes in the future.In chapter 6,we employed novel magnetic MOFs(zeolitic imidazolate framework-8)cladded by hemin and glucose oxidase(Fe3O4@ZIF-8@HG)to offer a high-sensitive and simple method for glucose determination with a wide response range(2.5-250 ?M),a low detection limit(1.25 ?M).Moreover,Fe3O4@ZIF-8@HG not only showed good catalytic activities inheriting from hemin and glucose oxidase but also had good magnetic property and stability,and thus excellent.In comparison with other glucose oxidase based sensors,utility of the present developed four-in-one functionalized compound sensors is more convenient,and the sensing operation can be finished within 15 min.In chapter 7,as the last chapter,novel highly fluorescent(FL)MOFs were synthesized by encapsulating CdTe quantum dots(CdTe-QDs)into the zeolitic imidazolate framework materials(ZIF-8).The as-synthesized FL-functionalized MOFs not only maintained an excellent FL activity and sensing selectivity inheriting from CdTe-QDs,but also could strongly and selectively accumulate target analytes due to the adsorption property of MOFs.The obtained CdTe@ZIF-8 composites have been used to develop an ultrasensitive and highly selective sensor for Hgig ion,with a wide response range(2 to 100 nM)and a low detection limit(1.5 nM),and have been successfully applied in the detection of Hg2+ ions in environmental water samples.