Papers by Author: Yue Qian Yang

Abstract: The niclel nanoparticles were prepared via polyol process with hydrazine hydrate as reductant, the optimum conditions were investigated and proposed to be the molar ratio of NiCl2: NaOH: Hydrazine hydrate =1: 2: 11, 60 °C, pH5.5. The qualified fluorescent-magnetic dual functional CdTe/Ni nanoparticles were synthesized via layer-by-layer (LBL) technique, Ni was designed to be magnetic core and CdTe was used as fluorescent shell material, the molar ratio of CdTe:Ni is 4.5:1. The morphology of the Ni nano particles and CdTe/Ni core shell dual functional nano particles were characterized by transmission electron microscopy (TEM), and optical properties were investigated with fluorescence spectrum (FS) and ultra violet spectrum (UV). The synthesized CdTe/Ni nanoparticles showed yellow fluorescence when excited at 365nm, CdTe/Ni magnetic core shell QDs can be simply precipitated with a common magnet. TEM data indicated that ~15nm of Ni nanoparticles were obtained and ~25nm of CdTe/Ni core shell dual functional nanoparticles were prepared. Red shift of maximum absorbance peak was detected via UV, and these results inferred the QDs growth, moreover, 40nm red shift of maximum emission wavelength from 530nm to 570nm was observed, and which showed the growth QDs and formation of CdTe shell. The prepared magnetic core shell CdTe/Ni nanoparticles showed excellent optical properties, and it is expected to be useful and helpful in DNA sensing based on fluorescence resonance energy transfer, biological separating, and DNA labeling process.

Abstract: The core-shell CdTe/ZnS quantum dots were prepared with an improved process in aqueous phase. CdTe QDs were synthesized under conditions of pH 9.1, 96 °C, refluxing for 5h, and which was used as core material; ZnS was formed as shell material to enhance the optical properties. Optical properties were characterized with fluorescence spectrum (FS), and morphology of QDs was investigated via transmission electron microscopy (TEM) method. Moreover, composition and formation of CdTe/ZnS core-shell QDs was characterized via x-ray diffraction (XRD) method. Optimum conditions were investigated to obtain the qualified CdTe/ZnS core-shell QDs, the results indicated QDs with high quantum yields and fluorescence intensity were achieved under conditions of pH 9.0, 45 °C, refluxing for 1h, and v/v/v ratio of CdTe/Na2S/ZnSO4 is 4/1/1. The TEM data indicated that average size of 5 nm CdTe core was prepared, and CdTe/ZnS core-shell QDs with average size of 11 nm were achieved under the optimum conditions. ca 30nm of red shift of a maximum emission wavelength from ca 530 nm (CdTe) to 560 nm (CdTe/ZnS) was observed via FS under the optimum conditions, which inferred the growth of QDs and formation of ZnS shells. Furthermore, the enhanced fluorescence intensity of CdTe/ZnS core-shell QDs was detected and over two times of fluorescence intensity was increased after formation of ZnS shell. The obtained QDs will have great potential application in biological researches and biosensing system based on fluorescence resonance energy transition (FRET).

Abstract: Quantum dots (QDs) are normally based on the semiconductor materials and widely used in biosensing, bioimaging, biolabeling, and biotreatment for their excellent properties. The ecotoxicity research of QDs correspondingly kept in rising in recent years. CdTe and CdTe/ZnS QDs were prepared via an improved process in aqueous phase, morphology of QDs was characterized with transmission electron microscopy, and optical properties were investigated via fluorescence spectrum. Ecotoxicity of CdTe and CdTe/ZnS were assayed by measuring the inhibitory growth of Rhodococcus sp. strain C1 when QDs existed in broth culture, which was screened from sewage, and its morphology was characterized with optical microscope and scanning electron microscope. CdTe QDs showed strong inhibitory effect against growth of Rhodococcus sp. strain C1, and little growth was observed after 72h cultivation. CdTe/ZnS QDs showed prophasic inhibition before 36h, and growth recovery was observed after 48h of cultivation. Enhanced optical properties and decreasing ecotoxicity were validated after ZnS shell formation, these results indicated that CdTe/ZnS QDs with core-shell structure has great potential in bio-applications.

Abstract: We presented a fast, specific, and sensitive DNA sensing system, which composed of a CdTe/Fe3O4 magnetic core-shell quantum dots (energy donor), a commercial quencher (BHQ2; energy acceptor), and a designed single strand Toxoplasma gondii DNA. The designed single strand Toxoplasma gondii DNA was applied to link the energy donor and acceptor, and target DNA was detected based on mechanism of fluorescence resonance energy transfer. The CdTe quantum dots, Fe3O4 magnetic nanoparticles, CdTe/Fe3O4 magnetic core-shell quantum dots, and sensing probe were step-wisely prepared. Properties of synthesized quantum dots were investigated by transmission electron microscopy, fluorescence spectrum, nano zeta potential and submicron particle size analyzer, and X-ray diffraction, respectively. Specificity and sensitivity of sensing probe was determined by measuring the recovery of fluorescence intensity. The obtained sensing probe with magnetic properties can be simply separated or concentrated from the hybridized solution with a common magnet. The resulting data revealed the sensing system was successfully fabricated, and which has high sensitivity and specificity.

Abstract: we introduced a fast, specific, and sensitive sensing probe to detect Toxoplasma gondii DNA based on mechanism of fluorescence resonance energy transfer (FRET), and a multifunctional and magnetic-fluorescent CdTe/Ni quantum dots (mQDs) was prepared as energy donor, and BHQ2 was used as energy acceptor, respectively. CdTe/Ni mQDs were synthesized with a more simple method using Ni nanoparticles as core material and CdTe as shell material. The sensing probe was fabricated through labeling a stem-loop Toxoplasma gondii DNA oligonucleotide with CdTe/Ni mQDs at the 5′ end and BHQ2 at 3′ end, respectively, and the resulting sensing probe can be conveniently isolated and purified with a common magnet. Properties of mQDs and sensing probe were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), and fluorescence spectrum (FS) methods. The TEM data demonstrated that the size of Ni nanoparticles was estimated to be ~10nm, and size of CdTe/Ni is 15nm. XRD data showed similar spectrum of CdTe and CdTe/Ni, intensity of Ni (111) typical diffraction peak was detected, which inferred the formation of CdTe on surface of Ni core. An obvious fluorescence recovery (FR) was observed when the complete complimentary target Toxoplasma gondii DNA was introduced comparing with the target DNA with one-basepair-mismatch, this result revealed the sensing probe has high sensitivity and specificity. The current sensing probe will has great potential applications in the life science and gene diagnostics.

Abstract: A novel CdTe/Ni QDs which combined both magnetism and fluorescence was successfully synthesized and its optical properties were investigated. Ni magnetic nanoparticles (MNPs) were synthesized and used as magnetic core, CdTe quantum dots (QDs) were applied as fluorescent shell material, the qualified magnetic CdTe/Ni quantum dots (mQDs) were achieved via layer-by-layer process using 1,6-hexylenediamime as linker, surface charge types of MNPs and mQDs were confirmed with a delsa nano beckman coulter. Morphology of the prepared Ni MNPs and CdTe/Ni mQDs was characterized by transmission electron microscopy (TEM), and optical properties were investigated with fluorescence spectrum (FS). Qualified CdTe/Ni mQDs with high fluorescence and narrow maximum emission peak width were obtained under the optimum conditions. Surface zeta-potential of CdTe QDs and Ni MNPs were estimated to be -36.2 and 27.97mV, respectively. TEM data indicated that ca 20nm of Ni MNPs and ca 25nm of CdTe/Ni mQDs were prepared, respectively; the size-increasing indicated the formation of CdTe shell on the Ni MNPs core. Narrow half peak width of emission peak was detected and calculated to be about 50nm via FS. High fluorescence intensity of CdTe/Ni mQDs was determined and brilliant yellow solution was observed when excited under UV360nm. The synthesized CdTe/Ni mQDs showed excellent magnetic property, and can be magnetically concentrated with a common magnet. The obtained data indicated that the prepared bi-functional CdTe/Ni mQDs possess excellent magnetic and fluorescent properties, and it can be used as a energy donor in DNA sensing based on fluorescence resonance energy transfer (FRET).