Synthesis Of Manganese Dioxide-based Nanocomposite Fluorescent Probes And Their Application In Glutathione Determination And Cancer Therapy

Glutathione(GSH)is a kind of widespread bio-thiol in the human body.It directly affects human life and health by participating in the metabolic process and is directly related to many diseases.More importantly,GSH shows abnormally high levels in cancer cells,therefore it provides a new approach for cancer diagnosis and identification as a specific indicator in the tumor microenvironment.Combining the excellent optical absorption and GSH-stimulated degradation properties of manganese dioxide nanomaterials,and the stable,sensitive and visual advantages of imaging of fluorescent probes,MnO2-based nanocomposite fluorescent probes show superiorities in chemo-biosensing,cell imaging,drug delivery and cancer treatment.Based on electrostatic interaction and in-situ reaction,three kinds of MnO2 based nanocomposite fluorescent probes(CDs-MnO2,GQDs-MnO2,CPs@MnO2-AgNPs)were prepared with MnO2 as the matrix material in this thesis.Through the spectral overlap and fluorescence lifetime variations,the fluorescence sensing mechanisms were studied.Based on this,fluorescent turn-on methods for GSH determination were established.These probes possessed the property of fluorescence imaging for cancer cells,and can further achieved chemotherapy/photothermal therapy for integrated cancer theranostic through external near-infrared stimulation.Chapter 1:The structures and properties of MnO2 nanomaterials,the sensing principle of MnO2-based nanocomposite fluorescent probes are summarized.The synthesis methods of MnO2 nanomaterials and MnO2-based nanocomposite fluorescent probes,and their research advances in biomedicine are reviewed.Chapter 2:Using bovine serum albumin as both a bio-template and a reductant,manganese dioxide nanoparticles(MnO2 NPs)were prepared from potassium permanganate,and further combined with carbon nanodots(CDs)based on electrostatic action to synthesize CDs-MnO2 nano-fluorescent probe.MnO2 quenched the fluorescence of CDs through fluorescence resonance energy transfer,and the introduction of GSH selectively stimulated the degradation of MnO2 to restore the fluorescence.The fluorescence intensity showed a GSH concentration dependent enhancement and fluorescence recovery efficiency(?F/F0)of the system showed a good linear relationship with the concentrations of GSH in the range of 0.05?90 ?mol/L,and the detection limit was 39 nmol/L.The CDs-MnO2 nano-fluorescent probe was applied to the determination of GSH in human serum sample,and the recovery rates were in the range of 94.28%?102.77%.Further,based on the significantly higher GSH content of cancer cells compared to normal cells,the nanoprobe achieved the fluorescent turn-on imaging of cancer cells.Compared to the weak fluorescence in L02 normal cells,SMMC-7721 cancer cells showed obvious blue fluorescence after incubation with CDs-MnO2Chapter 3:Graphene quantum dots(GQDs)were prepared from citric acid through pyrolysis,and square-plate-like graphene quantum dots-manganese dioxide nano-fluorescent probe(GQDs-MnO2)were prepared through an in-situ synthesis under ultrasonication in the presence of polyallylamine hydrochloride(PAH).The connection of the fluorescent material and MnO2 was realized during the preparation process,avoiding complicated post-modification or chemical bonding.The fluorescence of GQDs was firstly quenched by MnO2 through fluorescence resonance energy transfer.After the addition of GSH,MnO2 was degraded and the fluorescence was restored.Thus,a GQDs-MnO2-based fluorescent turn-on probe was established for the determination of GSH.The linear range of this method was 0.07?70 ?mol/L with a detection limit of 48 nmol/L,and it showed good selectivity.GQDs-MnO2 nanoprobe was further applied to the determination of GSH in human serum sample,and the recovery rates were in the range of 102.67%?106.84%.Besides,the GQDs-MnO2 nanoprobe showed fluorescent imaging property to recognize cancer cells.The probe was stimulated by high concentration of GSH in SMMC-7721 cancer cells to generate fluorescence recovery,and achieved the fluorescent turn-on imaging of cancer cellsChapter 4:Carbon nanoparticles@manganese dioxide nanocomposites(CPs@MnO2)were prepared by coating manganese dioxide nano-layers on the surface of CPs by ultrasonic-assisted in-situ redox reaction.Amino groups were further modified on surface of CPs@MnO2 by coating silylating agent APTES making nanocomposite positively charged;Silver nanoparticles(AgNPs)were synthesized through a silver-mirror-like reaction method,and further anchored on CPs@MnO2 to construct CPs@MnO2-AgNPs nano-fluorescent probe.Through internal filtration effect and static quenching effect,MnO2 effectively quenched the fluorescence of AgNPs,but it was degraded under GSH stimulation and thus the fluorescence is restored.The nanoprobe showed a linear response to GSH in the concentration range of 0.8?80 ?mol/L with a detection limit of 0.55 ?mol/L.More importantly,MnO2 nanoshell can be degraded in cancer cells by GSH,which is highly expressed,leading to the fluorescence turn-on of AgNPs as well as exposure of CPs as the core.Combined with the anti-cancer effect of AgNPs themselves and the photothermal performance of CPs under the illumination of near-infrared light.CPs@MnO2-AgNPs showed the theranostic performance against cancer.Compared with L02 normal cells,SMMC-7721 cancer cells showed obvious red fluorescence after incubation with the nanoprobe.Meanwhile,CPs@MnO2-AgNPs showed higher cytotoxicity under near-infrared radiation at 808 nm.Therefore,the nanocomposite fluorescent probe achieved the integration of cancer theranostic in combination with fluorescent turn-on imaging,chemotherapy and photothermal therapy.