Wenping Jia

A DNA-stabilized silver nanoclusters/graphene oxide-based platform for the sensitive detection of DNA through hybridization chain reaction.

A silver nanoclusters (AgNCs)/graphene oxide (GO)-based fluorescence sensor was developed for label-free DNA detection through hybridization chain reaction (HCR). A DNA sequence associated with the human immunodeficiency virus (HIV) was selected as a model target. Two DNA probes, hairpin probe 1 (H1) and hairpin probe 2 (H2), were partially complementary. GO was used as an adsorption material to capture the hairpin probes and a selective fluorescence quencher was used to reduce the background signal. Upon addition of AgNO3 and NaBH4, the AgNCs were synthesized at the terminals of the H1 and H2 probes. In the absence of target DNA (THIV), hybridization chain reaction (HCR) could not be triggered due to the stability of H1 and H2 probes. The hairpin probe-protected AgNCs attached to the GO surface, efficiently quenching fluorescence of the AgNCs. Therefore, the system showed very low background. In presence of THIV, the target triggered the chain-like assembly of H1 and H2 through HCR, generating a long chain of H1 and H2 complexes. The HCR product (AgNCs nanowires) could not be adsorbed on the surface of GO; hence, it generated a strong fluorescent signal based on the concentration of the target. Under the optimized conditions, the detection limit of the fluorescence sensor was 1.18nM, and hence it can be applied to clinical samples.

The synthesis and characterization of monodispersed chitosan-coated Fe3O4 nanoparticles via a facile one-step solvothermal process for adsorption of bovine serum albumin.

Preparation of magnetic nanoparticles coated with chitosan (CS-coated Fe3O4 NPs) in one step by the solvothermal method in the presence of different amounts of added chitosan is reported here. The magnetic property of the obtained magnetic composite nanoparticles was confirmed by X-ray diffraction (XRD) and magnetic measurements (VSM). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) allowed the identification of spherical nanoparticles with about 150 nm in average diameter. Characterization of the products by Fourier transform infrared spectroscopy (FTIR) demonstrated that CS-coated Fe3O4 NPs were obtained. Chitosan content in the obtained nanocomposites was estimated by thermogravimetric analysis (TGA). The adsorption properties of the CS-coated Fe3O4 NPs for bovine serum albumin (BSA) were investigated under different concentrations of BSA. Compared with naked Fe3O4 nanoparticles, the CS-coated Fe3O4 NPs showed a higher BSA adsorption capacity (96.5 mg/g) and a fast adsorption rate (45 min) in aqueous solutions. This work demonstrates that the prepared magnetic nanoparticles have promising applications in enzyme and protein immobilization.

Luminescent properties of CdTe quantum dots synthesized using 3-mercaptopropionic acid reduction of tellurium dioxide directly

A facile one-step synthesis of CdTe quantum dots (QDs) in aqueous solution by atmospheric microwave reactor has been developed using 3-mercaptopropionic acid reduction of TeO2 directly. The obtained CdTe QDs were characterized by ultraviolet–visible spectroscopy, fluorescent spectroscopy, X-ray powder diffraction, multifunctional imaging electron spectrometer (XPS), and high-resolution transmission electron microscopy. Green- to red-emitting CdTe QDs with a maximum photoluminescence quantum yield of 56.68% were obtained.

Fluorogenic boronate-based probe-lactulose complex for full-aqueous analysis of peroxynitrite

A selective fluorogenic boronate-based probe-lactulose complex was evaluated for the rapid analysis of peroxynitrite (ONOO-) based on a reaction-based indicator displacement assay (RIA). The probe was synthesised by a simple nucleophilic substitution reaction between a boronic acid moiety and a well known laser dye, DCM. Fluorescence analyses showed that the probe had an off-on response to lactulose, forming a fluorogenic probe-lactulose complex. The subsequent addition of ONOO- selectively quenched the fluorescence of the complex over other Reactive Oxygen/ Nitrogen Species (ROS/RNS) tested. The complex can be applied for the rapid determination of ONOO- in full aqueous solution with good linear range, and has also proven suitable for monitoring ONOO- in living cells and real water samples.

Facile synthesis of folate-conjugated magnetic/fluorescent bifunctional microspheres.

In this paper, we investigated the functional imaging properties of magnetic microspheres composed of magnetic core and CdTe quantum dots in the silica shell functionalized with folic acid (FA). The preparation procedure included the preparation of chitosan-coated Fe3O4 nanoparticles (CS-coated Fe3O4 NPs) prepared by a one-pot solvothermal method, the reaction between carboxylic and amino groups under activation of NHS and EDC in order to obtain the CdTe-CS-coated Fe3O4 NPs, and finally the growth of SiO2 shell vent the photoluminescence (PL) quenching via a Stöber method (Fe3O4-CdTe@SiO2). Moreover, in order to have a specific targeting capacity, the magnetic and fluorescent bifunctional microspheres were synthesized by bonding of SiO2 shell with FA molecules via amide reaction (Fe3O4-CdTe@SiO2-FA). The morphology, size, chemical components, and magnetic property of as-prepared composite nanoparticles were characterized by ultraviolet-visible spectroscopy, fluorescent spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning transmission electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM), respectively. The results show that the magnetic and fluorescent bifunctional microspheres have strong luminescent which will be employed for immuno-labeling and fluorescent imaging of HeLa cells.

Facile synthesis of Ag@Fe3O4@C-Au core-shell microspheres for surface-enhanced Raman scattering

In this paper, a facile approach has been developed to synthesize the novel multifunctional Ag@Fe3O4@C-Au magnetic core-shell microspheres that display a highly efficient surface-enhanced Raman scattering (SERS) substrate with high stability and reproducibility. The morphology, size, chemical component, and magnetic property of as-prepared composite microspheres were characterized by scanning transmission electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectra (XPS), and vibrating sample magnetomerter (VSM), respectively. The enhancement effect on the Raman active was investigated by using rhodamine-b (RdB) as a probe molecule. The result shows that the well-designed Ag@Fe3O4@C-Au core-shell microspheres have uniform sphere size and high magnetization, and the SERS signals of RdB on the Ag@Fe3O4@C-Au microspheres were much stronger than those on both Ag@Fe3O4 and Fe3O4@C-Au microspheres.

Highly efficient and porous TiO2-coated Ag@Fe3O4@C-Au microspheres for degradation of organic pollutants

In this paper, we reported a novel hierarchical porous Ag@Fe3O4@C-Au@TiO2 core@shell microspheres with a highly photocatalytic activity and magnetically separable properties. The synthesis method is included of a Fe3O4 magnetic embedded Ag core (Ag@Fe3O4), an interlayer of carbon modified by PEI to form sufficient amounts of amine functional groups (Ag@Fe3O4@C-PEI), the grafting of Au nanoparticles on the surface of Ag@Fe3O4@C-PEI (Ag@Fe3O4@C-Au), and an ordered porous TiO2 structured shell. As an example of the applications, the photocatalytic activities of the samples were investigated by the reduction of Rhodamine B (RhB) under visible-light irradiation. The results show that the porous Ag@Fe3O4@C-Au@TiO2 core@shell microspheres display higher adsorption and photocatalytic activities compared to the pure porous TiO2 and Ag@Fe3O4@C@TiO2 microspheres, which are attributed to the local surface plasmon resonance (LSPR) by the Ag and Au nanoparticles and the high specific surface area.

FACILE SOLVOTHERMAL SYNTHESIS OF MESOSTRUCTURED CHITOSAN-COATED Fe3O4 NANOPARTICLES AND ITS FURTHER MODIFICATION WITH FOLIC ACID FOR IMPROVING TARGETED DRUG DELIVERY

Mesostructured chitosan-coated Fe3O4 nanoparticles (CS-coated Fe3O4 NPs) were synthesized by a facile one-step solvothermal method via using chitosan as a surface-modification agent. Subsequently, the surfaces of CS-coated Fe3O4 NPs were successfully conjugated with folic acid (FA) molecules to obtain FA–CS-coated Fe3O4 NPs for improving targeted drug delivery. The morphology, chemical component and magnetic property of as-prepared composite nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), scanning transmission electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and vibrating sample magnetometer (VSM). Furthermore, doxorubicin hydrochloride (DOX) as a model drug was encapsulated for investigating drug release pattern in vitro. The results show that the magnetization saturation value of FA–CS-coated Fe3O4 NPs was about 28.5 emu/g, exhibiting superparamagnetic properties and mesostructure. DOX could be loaded to FA–CS-coated Fe3O4 NPs with high capacity about 27.9%, and the release rate of DOX could be adjusted by the pH value. This work demonstrates that the prepared magnetic nanoparticles have potential applications in the treatment of cancer as targeting drug delivery carriers.