| Due to the unique structure,graphene-like nanomaterials display unexpected physicochemical and electronic properties,such as the large surface area,excellent thermal conductivity and electric conductivity,ease of functionalizing the surfaces,etc.They find wide applications in biosensing,biological imaging,drug loading and delivering,photocatalytic or electrocatalysis,and electrochemical energy and storage.However,some facile,simple and efficient approaches have been proposed to synthesize some novel graphene-like nanomaterials,which show some superior performances.And a series of functional and surface modification of graphene-like nanomaterials are utilized for development of their properties to extend its applications of graphene-like nanomaterials.Above all is the key of research field of graphene-like nanomaterials.In view of these challenges,we prepare a variety of graphene-like nanomaterials.And some new nanocomposites are obtained by functionalized modifications.Based on the different properties of these nanomaterials,they have been applied to the fields of biological detection and environmental pollution treatment so as to establish the system of biological detection or photocatalytic degradation.Details are described as below:1.The graphene quantum dots(GQDs)were prepared by ultraviolet irradiation.And bright blue luminescent GQDs with major graphitic structured nanocrystals and a photoluminescence(PL)quantum yield of 15.5%are synthesized.The as-prepared GQDs showed excitation-dependent PL and stable electrochemiluminescence(ECL)behaviors.Gold nanoparticles(AuNPs)were linked with a probe of single-stranded DNA(cp53 ssDNA)to form AuNPs-ssDNA.The ECL signal of the GQDs could be quenched by non-covalent binding of the AuNPs-ssDNA to the GQDs,due to the occurrence of an electrochemiluminescence resonance energy transfer between the GQDs and the AuNPs.When AuNPs-ssDNA was then hybridized with target p53 DNA to form AuNPs-dsDNA,the non-covalent interaction between the GQDs and the ds-DNA weakened and the ECL of the GQDs recovered.This engendered an ECL sensor for the detection of target p53 ssDNA,with a detection limit of 13 nM.The resultant ECL sensor could be used for DNA damage detection based on its different bonding ability to damaged target p53 ssDNA and cp53 ssDNA linked AuNPs.The presented method could be expanded to the development of other ECL biosensors,for the quantification of nucleic acids,single nucleotide polymorphisms or other aptamer-specific biomolecules.2.Sensitive assay and imaging multiple low-abundance microRNAs(miRNAs)in live cells remain a grand challenge.Herein,based on polyelectrolyte inducing reduction,a facile approach has been proposed to synthesize novel Mn02 nanotubes.Owing to the remarkably strong fluorescence quenching ability,low cytotoxicity and excellent colloid stability,MnO2 nanotubes are utilized for development of a nanocomplex(MnO2 NTs-ssDNA),which is a fluorescent probe.Once endocytosed into MCF-7 cells,target miRNAs will be recognized by ssDNA to form miRNA-ssDNA complexes,which could release ssDNA from the surface of MnO2 nanotubes.The quenched fluorescence signals will be recovered as "light-on" statue for illuminating the specific miRNAs in situ in living cells.Futhermore,there are some glutathione in the breast cancer cells.Upon the addition of GSH,Mn02 nanotubes is reduced to Mn2+,which could be used as a contrast agent of magnetic resonance imaging(MRI).Herein,we present the first MnO2 nanotube as a new kind of 1D nanomaterials based nanoprobe for multiple fluorescence imaging and MRI in living cells,which can serve as a noninvasive method to provide comprehensive insights on suspected tumors and assist in cancer screening and early detection.3.In order to improve the fluorescent properties of graphene quantum dots,metal porphyrin compounds(FePor)and graphene quantum dots(GQDs)are linked together attributed to van der Waals force and ?-? stacking.Glutathione(GSH)and L-cysteine(Cys)play important roles in vivo.The structure of them contains a reactive sulfhydryl(-SH),which is susceptible to oxidative dehydrogenation.So the Mn02 NTs could be decomposed Mn2+ by GSH and Cys.Based on the excellent fluorescence quenching performance of MnO2 NTs,we utilized the fluorescence resonance energy transfer(FRET)from GQDs/FePor to MnO2 NTs constructing a "turn off" fluorescence nano-system for selective and fast quantifying the level of GSH or Cys.Additionally,due to its biological compatibility and low cytotoxicity,the "turn off"fluorescence nano-system could be expended monitoring dimensional and temporal distribution of GSH in vivo.4.A novel nanocomposite of zinc porphyrin functionalized graphene quantum dots(GQDs/ZnPor)was prepared and used as a photocatalyst for the degradation of an organic pollutant under visible-light irradiation.In order to synthesise the nanocomposites,large graphene sheets were first cleaved into small pieces of graphene oxide by a mixture of concentrated H2S04 and HN03.Then GQDs/ZnPor was synthesized by a simple hydrothermal route with ZnPor and the as-synthesized graphene oxide as precursors.The resultant GQDs/ZnPor nanocomposites were characterized by transmission electron microscopy(TEM)and optical measurements.The photocatalytic activity of GQDs/ZnPor was evaluated by the degradation of methylene blue(MB)under visible-light irradiation.Enhancement of the photocatalytic activity of GQDs/ZnPor compared with pure zinc porphyrin was was explained by the increased effective contact area and the changed surface charge of zinc porphyrin due to the GQDs as well as large surface area and excellent electron conductivity of the photogenerated carriers.The photocatalytic degradation mechanism of GQDs/ZnPor was also illustrated by photoluminescence measurements of free radical and holes scavenging experiments.During the recovery experiment,GQDs/ZnPor exhibited adequate catalytic stability,performing as a genuine visible-light-driven photocatalyst to decompose aqueous organic pollutants effectively. |
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