| Intracellular reducing substances are involved in various reactions in the body and are closely relevant to human health,so the detections of reducing substances in living cells or in vivo are important.Among the existing detection technologies,fluorescent assay based techniques received extensive attention for its high sensitivity and selectivity.In recent years,a large number of fluorescent probes were used to detect biological small molecules and active substances in the body.However,the excitation and emission wavelength of most of these probes are in theUV-Vis region,which have some inevitable shortcomings,such as high fluorescence background,light bleaching effect and the shallow penetration depth in the tissue.The development of two-photon(TP)imaging technology promoted the researches of two-photon fluorescence probes.TP fluorescence imging are excitated by the near infrared light,which can avoid the spontaneous fluorescence interference of the organism and reduce the light scattering.Owing to these features,the TP probes can achieve deeper tissue depth imaging.Near infrared(NIR)nanomaterials as a new nanometer material have many remarkable advantages,such as deeper tissue penetration ability,weak emission of light scattering and lower fluorescence background.Up to now,a number of NIR materials have been synthesized and used for biological samples detection and imaging in tissue or in vivo.In this thesis,via the research of the TP fluorescence probes,based on fluorescence resonance energy transfer(FRET)we designed a ratiometric TP fluorescence probe(TPR-S)for the H2Sn detection and lipopolysaccharide caused acute injury of organ imaging.Based on the near-infrared quantum dots(NGs)and hydroxy cobalt oxide(CoOOH)nanomaterials,we designed and synthesized a TP probe(CoOOH-NGs),which can realize the analysis of endogenous ascorbic acid(AA)in cells and achieve deep tissue imaging.The main contents are as follows:(1)In chapter 2,by introducing 2-fluoro-5-nitro benzoic acid as recognition unit of H2Sn,based on the ratio of FRET,we designed and synthesized a model of two-photon fluorescence probe(TPR-S)to detect H2Sn.TPR-S exhibits high selectivity and sensitivity for H2Sn,with a detection limit of 0.7 ?M,TPR-S can also be used to detect the Na2S4 in cells and in tissues.More importantly,TPR-S may be used to detect H2Sn in LPS-induced organ injury samples.All of these features demonstrate that TRP-S is promising for practical applications in biological systems.(2)In chapter 3,we first synthesized the near infrared graphene quantum dots(NGs).Next we synthesised cobalt oxide nanometer sheet(CoOOH)on the surface of the NGs via situ synthesis and built an activation nanoprobe(CoOOH-NGs).In the probe,the NGs act as signal report unit and CoOOH nanoflakes act as fluorescence quenching agent can quench the fluoresecence of NGs,CoOOH also can effectively identify the ascorbic acid.In the presence of ascorbic acid(AA),the CoOOH was reduced to Co2+,resulting in the decomposition of the CoOOH nanoflakes and leading to fluorescence recovery of the NGs.Experimental results showed that the nanoprobe has uniform size and good dispersion.What's more,the influence of pH and reaction medium is small and can be effectively used in the detection of AA.(3)In chapter 4,based on the near-infrared fluorescent probe(CoOOH-NGs)we designed and synthesized in the chapter 3,we further studied the two-photon properties of graphene quantum dots,and used for the analysis of endogenous ascorbic acid in cell.The experimental results show that the probe has large two-photon absorption cross section and the advantage of both two-photon probes and near infrared probes,such as the low fluorescence background and less damage to the organization.CoOOH-NGs can achieve the tissue penetration depth of 40-320 ?m and possess good imaging ability.These result revealed that the CoOOH-NGs probe can be effectively used in the detection of endogenous ascorbic acid in the cells and used in the deep tissue imaging in the tissues. |
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