Microwave-assisted one-pot synthesis of water-soluble rare-earth doped fluoride luminescent nanoparticles with tunable colors.

Polyethyleneimine (PEI) functionalized multicolor luminescent LaF(3) nanoparticles were synthesized via a novel microwave-assisted method, which can achieve fast and uniform heating under eco-friendly and energy efficient conditions. The as-prepared nanoparticles possess a pure hexagonal structure with an average size of about 12 nm. When doped with different ions (Tb(3+) and Eu(3+)), the morphology and structure of the nanoparticles were not changed, whereas the optical properties varied with doped ions and their molar ratio, and as a result emission of four different colors (green, yellow, orange and red) were achieved by simply switching the types of doping ions (Eu(3+) versus Tb(3) +) and the molar ratio of the two doping ions.

Polyethyleneimine modified fluorescent carbon dots and their application in cell labeling.

Fluorescent carbon dots (CDs) were solvothermaly synthesized in water-glycol medium by using glucose as carbon source and then modified with polyethyleneimine (PEI) for the first time to improve fluorescence quality. The as-prepared CDs were monodispersed sphere particles with a diameter of about 7.5 nm, emitting strong fluorescence which is excitation wavelength-dependent, with a quantum yield of 3.5%. After PEI modification, there was a 300-fold enhancement in fluorescence intensity and also a red shift in emission wavelength. The as-prepared CDs were then conjugated with CEA8 antibody to label and image HeLa cells in vitro. We also tested the cytotoxicity of these CDs using HeLa cells. No apparent cytotoxicity was observed, demonstrating much better biosafety property compared with CdTe quantum dots.

Synthesis of NaYF(4):Yb,Er/single-walled carbon nanohorns nanocomposite and its application as cells label.

A novel nanocomposite synthesis method of amino-modified NaYF(4):Yb,Er upconversion luminescent nanoparticles and single-walled carbon nanohorns was developed via covalent linkage for the first time. The nanocomposite was covalently coupled with rabbit anti-CEA8 antibody and then used successfully as a cell labeling agent for the immunolabeling and imaging of HeLa cells.

[Biosynthesis of CdS quantum dots in Saccharomyces cerevisiae and spectroscopic characterization].

In the present work, CdS quantum dots (QDs) were successfully biosynthesized at room temperature by using saccharomyces cerevisiae yeast as a carrier. Fluorescence emission spectra, ultraviolet-visible (UV/Vis) absorption spectra, and inverted fluorescence microscope images confirmed that saccharomyces cerevisiae can be used to biosynthesize CdS QDs. The as-prepared CdS QDs show the fluorescence emission peak at 443 nm and emit blue-green fluorescence under UV light (with excitation at 365 nm). Transmission electron microscopy (TEM) was applied to characterize the as-prepared CdS QDs and the TEM results showed that the as-prepared CdS QDs had the structure of hexagonal wurtzite. Fluorescence emission spectrum and UV/Vis absorption spectrum were used as the performance indicatiors to study the effects of saccharomyces cerevisiae yeast incubation times, reactant Cd2+ concentrations and reaction times on CdS QDs synthesis. Saccharomyces cerevisiae yeast grown in early stable phase can get the highest fluorescence intensity of CdS QDs when they were co-cultured with 0.5 mmol x L(-1) of Cd2+ with 24 h incubation time. Furthermore, much more CdS QDs can be obtained by changing the culture medium during the synthesis process.

Hydrothermal synthesis of GSH-TGA co-capped CdTe quantum dots and their application in labeling colorectal cancer cells.

We have successfully synthesized GSH and TGA co-capped CdTe quantum dots (QDs) with good biological compatibility and high fluorescence intensity. The effects of different reaction time, temperature, pH value, ligand concentration and the molar ratio of GSH/TGA were carefully investigated to optimize the synthesis condition. The optical properties of as-prepared CdTe QDs were studied by UV-visible absorption spectrum and fluorescence spectrum, meanwhile their structure and morphology were characterized using transmission electron microscope (TEM), Fourier transform infrared spectra (FT-IR) and X-ray powder diffraction (XRD). Compared with the CdTe QDs that are single-capped with either GSH or TGA, the GSH-TGA co-capped CdTe QDs demonstrated significantly improved fluorescence intensity and optical stability. In addition, GSH-TGA co-capped CdTe QDs were conjugated to amonoclonal antibody ND-1. The GSH-TGA co-capped CdTe QDs-antibody probe was successfully used to label colorectal cancer cells, CCL187, in vitro.

Synthesis of NaYF(4):Yb/Er/Gd up-conversion luminescent nanoparticles and luminescence resonance energy transfer-based protein detection.

High-quality NaYF4:Yb/Er/Gd up-conversion nanoparticles (UCNPs) were first synthesized by a solvothermal method using rare earth stearate, sodium fluoride, ethanol, water, and oleic acid as precursors. Doped Gd³âº ions can promote the transition of NaYF4 from cubic to hexagonal phase, shorten the reaction time, and reduce the reaction temperature without reducing the luminescence intensity of NaYF4:Yb/Er UCNPs. X-ray diffraction, infrared spectroscopy, transmission electron microscopy, and luminescence spectroscopy were applied to characterize the UCNPs. The nanoparticles exhibited small size and excellent green up-conversion photoluminescence, making them suitable for biological applications. After the surfaces of NaYF4:Yb/Er/Gd UCNPs were modified with amino groups through the Stöber method, they could be brought close enough to the analytically important protein called R-phycoerythrin (R-PE) bearing multiple carboxyl groups so that energy transfer could occur. A luminescence resonance energy transfer (LRET) system was developed using NaYF4:Yb/Er/Gd UCNPs as an energy donor and R-PE as an energy acceptor. As a result, a detection limit of R-PE of 0.5 µg/ml was achieved by the LRET system with a relative standard deviation of 2.0%. Although this approach was first used successfully to detect R-PE, it can also be extended to the detection of other biological molecules.

Novel microwave-assisted solvothermal synthesis of NaYF4:Yb,Er upconversion nanoparticles and their application in cancer cell imaging.

This work reports the novel microwave-assisted solvothermal synthesis and structural, topographic, spectroscopic characterization of NaYF(4):Yb,Er upconversion nanoparticles (UCNPs) as well as their application in the labeling of HeLa cells. The nanoparticles were prepared in ethylene glycol, with rare earth acetates as precursor and NH(4)F and NaCl as the fluorine and sodium sources. X-ray diffraction, transmission electron microscopy, and luminescence spectroscopy were applied to characterize the nanoparticles. Experimental results showed that the microwave-assisted solvothermal method is an effective approach to create highly crystalline, strongly luminescent UCNPs at a lower temperature (160 °C) and within a significantly shortened reaction time (only 1 h) compared to the traditional methods. The effect of fluorine source on the optical properties of UCNPs was investigated by using NH(4)F, NH(4)HF(2), NaF, and 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF(4)) as different fluorine sources; NH(4)F proved to be the best one, making the luminescent intensity increase at least 2 orders of magnitude. The UCNPs with four different colors (green, yellow, orange, and cyan) were successfully obtained. After being modified with amino groups and coupled with CEA-8 antibody, the obtained nanoparticles were successfully applied in the specific fluorescent immunolabeling and imaging of HeLa cells to further verify their function as a marker in immunolabeling.

Study on the sonodynamic activity and mechanism of promethazine hydrochloride by multi-spectroscopic techniques.

In this paper, the bovine serum albumin (BSA) was selected as a target molecule, the sonodynamic damage to protein in the presence of promethazine hydrochloride (PMT) and its mechanism were studied by the means of absorption, fluorescence and circular dichroism (CD) spectra. The results of hyperchromic effect of absorption spectra and quenching of intrinsic fluorescence spectra indicate that the ultrasound-induced BSA molecules damage is enhanced by PMT. The damage degree of BSA molecules increases with the increase of ultrasonic irradiation time and PMT concentration. The results of synchronous fluorescence, three-dimensional fluorescence and CD spectra confirmed that the synergistic effects of ultrasound and PMT induced the damage of BSA molecules. The results of oxidation-extraction photometry with several reactive oxygen species (ROS) scavengers indicate that the damage of BSA molecules could be mainly due to the generation of ROS and both (1)O(2) and OH are the important mediators of the ultrasound-induced BSA molecules damage in the presence of PMT.

Controllable synthesis of NaYF(4) : Yb,Er upconversion nanophosphors and their application to in vivo imaging of Caenorhabditis elegans.

ß-NaYF(4) : Yb,Er upconversion nanoparticles (UCNPs) can emit bright green fluorescence under near-infrared (NIR) light excitation which is safe to the body and can penetrate deeply into tissues. The application of UCNPs in biolabeling and imaging has received great attention recently. In this work, ß-NaYF(4) : Yb,Er UCNPs with an average size of 35 nm, uniformly spherical shape, and surface modified with amino groups were synthesized by a one-step green solvothermal approach through the use of room-temperature ionic liquids as the reactant, co-solvent and template. The as-prepared UCNPs were introduced into Caenorhabditis elegans (C. elegans) to achieve successful in vivo imaging. We found that longer incubation time, higher UCNP concentration and smaller UCNP size can make the in vivo fluorescence of C. elegans much brighter and more continuous along their body. The worms have no apparent selectivity on ingestion of the UCNPs capped with different capping ligands while having similar size and shape. The next generation of worms did not show fluorescence under excitation. In addition, low toxicity of the nanoparticles was demonstrated by investigating the survival rates of the worms in the presence of the UCNPs. Our work demonstrates the potential application of the UCNPs in studying the biological behavior of organisms, and lays the foundation for further development of the UCNPs in the detection and diagnosis of diseases.

Biosynthesis and characterization of CdS quantum dots in genetically engineered Escherichia coli.

Quantum dots (QDs) were prepared in genetically engineered Escherichia coli (E. coli) through the introduction of foreign genes encoding a CdS binding peptide. The CdS QDs were successfully separated from the bacteria through two methods, lysis and freezing-thawing of cells, and purified with an anion-exchange resin. High-resolution transmission electron microscopy, X-ray diffraction, luminescence spectroscopy, and energy dispersive X-ray spectroscopy were applied to characterize the as-prepared CdS QDs. The effects of reactant concentrations, bacteria incubation times, and reaction times on QD growth were systematically investigated. Our work demonstrates that genetically engineered bacteria can be used to synthesize QDs. The biologically synthesized QDs are expected to be more biocompatible probes in bio-labeling and imaging.

The influence of ultrasound on the fluoroquinolones antibacterial activity.

In this work, the antibacterial effect of fluoroquinolones (FQs) upon Escherichia coli (E.coli) was measured with and without application of 40 kHz ultrasound (US) stimulation. The research results demonstrated that simultaneous application of 40 kHz US apparently enhanced the antibacterial effectiveness of FQs. That is, the synergistic effect was observed and the bacterial viability was reduced when FQs and US were combined. In addition, various influencing factors, such as FQs drug concentration, US irradiation time and solution temperature, on the inhibition of E.coli were also investigated. The antibacterial activity was enhanced apparently with increasing of FQs drug concentration, US irradiation time and solution temperature. Furthermore, we discussed preliminarily the mechanism of US enhanced antibacterial activity. Results show that US can activate FQs to produce reactive oxygen species (ROS) indeed, which are mainly determined as superoxide radical anion (·O(2)(-)) and hydroxyl radical (·OH).

Upconversion nanoparticles: synthesis, surface modification and biological applications.

New generation fluorophores, also termed upconversion nanoparticles (UCNPs), have the ability to convert near infrared radiations with lower energy into visible radiations with higher energy via a nonlinear optical process. Recently, these UCNPs have evolved as alternative fluorescent labels to traditional fluorophores, showing great potential for imaging and biodetection assays in both in vitro and in vivo applications. UCNPs exhibit unique luminescent properties, including high penetration depth into tissues, low background signals, large Stokes shifts, sharp emission bands, and high resistance to photobleaching, making UCNPs an attractive alternative source for overcoming current limitations in traditional fluorescent probes. In this article, we discuss the recent progress in the synthesis and surface modification of rare-earth doped UCNPs with a specific focus on their biological applications. FROM THE CLINICAL EDITOR: Upconversion nanoparticles - a new generation of fluorophores - convert near infrared radiations into visible radiations via a nonlinear optical process. These UCNPs have evolved as alternative fluorescent labels with great potential for imaging and biodetection assays in both in vitro and in vivo applications.

Spectroscopic investigation on the synergistic effects of ultrasound and dioxopromethazine hydrochloride on protein.

The bovine serum albumin (BSA) was selected as a target molecule, the sonodynamic damage to protein in the presence of dioxopromethazine hydrochloride (DPZ) and its mechanism were studied by means of absorption and fluorescence spectra. The results of hyperchromic effect of absorption spectra and quenching of intrinsic fluorescence spectra indicated that the synergistic effects of ultrasound and DPZ could induce the damage of BSA molecules. The damage degree of BSA molecules increased with the increase of ultrasonic irradiation time and DPZ concentration. The results of synchronous fluorescence and three-dimensional fluorescence spectra further confirmed that the synergistic effects of ultrasound and DPZ induced the damage of BSA molecules. The results of oxidation-extraction photometry with several reactive oxygen species (ROS) scavengers indicated that the damage of BSA molecules could be mainly due to the generation of ROS, in which both (1)O(2) and ·OH were the important mediators of the ultrasound-inducing BSA molecules damage in the presence of DPZ.

L-Cysteine capped CdTe-CdS core-shell quantum dots: preparation, characterization and immuno-labeling of HeLa cells.

Functionalized CdTe-CdS core-shell quantum dots (QDs) were synthesized in aqueous solution via water-bathing combined hydrothermal method using L-cysteine (L-Cys) as a stabilizer. This method possesses both the advantages of water-bathing and hydrothermal methods for preparing high-quality QDs with markedly reduced synthesis time, and better stability than a lone hydrothermal method. The QDs were characterized by transmission electronic microscopy and powder X-ray diffraction and X-ray photoelectron spectroscopy. The CdTe-CdS QDs with core-shell structure showed both enhanced fluorescence and better photo stability than nude CdTe QDs. After conjugating with antibody rabbit anti-CEACAM8 (CD67), the as-prepared l-Cys capped CdTe-CdS QDs were successfully used as fluorescent probes for the direct immuno-labeling and imaging of HeLa cells. It was indicated that this kind of QD would have application potential in bio-labeling and cell imaging.

Spectroscopic investigation on protein damage by ciprofloxacin under ultrasonic irradiation.

In recent years, sonodynamic activities of many drugs have attracted more and more attention of researchers. The correlative study will promote the development of sonodynamic therapy (SDT) in anti-tumor treatment. In this work, bovine serum albumin (BSA) was used as a protein model to investigate the intensifying effects of ciprofloxacin (CPFX) ultrasonically induced protein damage by UV-vis and fluorescence spectra. Meanwhile, the conformation of BSA is changed upon the addition of CPFX and metal ions under ultrasound (US) so that the damaging site of BSA is considered. Various influencing factors, such as US irradiation time, metal ions, solution temperature and ionic strength, on the ultrasonically induced BSA damage are discussed. It was showed that CPFX could enhance ultrasonically induced BSA damage. The damage degree of BSA was aggravated with the increasing of US irradiation time, solution temperature, ionic strength as well as the addition of metal ions. Furthermore, the reactive oxygen species (ROS) in reaction system were detected by oxidation-extraction photometry (OEP). Experimental results also showed that US could activate CPFX to produce ROS, which were mainly determined as superoxide radical anion (.O2-) and hydroxyl radical (.OH).

Graphene-CuO nanocomposite.

Graphene-CuO nanocomposite was synthesized by a simple wet chemical approach. Using Cu(CH3COO)2 as the starting material, CuO was synthesized and loaded on the graphene sheets through the reaction with NH3H2O in alkaline system. Transmission electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy and Thermogravimetric analysis were employed to characterize the as-prepared sample. The detailed investigations revealed that the nanoparticles, which loaded on the graphene sheets, were pure CuO with the size of approximately 4-10 nm and possessed a monoclinic structure.

Graphene-Pd composite as highly active catalyst for the Suzuki-Miyaura coupling reaction.

The graphene-supported Pd catalyst was synthesized using the graphene-Pd salt as precursor. Transmission electron microscope and powder X-ray diffraction analysis indicated the Pd nanoparticles, which supported on the surface of the graphene sheets possessed a face-centered cubic structure and were with the size of 4-8 nm. The Suzuki-Miyaura reaction was employed to analyze the catalytic activity of the graphene-supported Pd catalyst. HPLC analysis indicated that the yield of biphenyl was 97% when the reaction only lasted 10 min. The experimental results showed the graphene sheets were great support for ligand-free Pd catalyst.

Synthesis and characterization of polymer eight-coordinate (enH2)[YIII(pdta)(H2O)](2)·10H2O as well as the interaction of [YIII(pdta)(H2O)]2(2-) with BSA.

The eight-coordinate (enH2)[YIII(pdta)(H2O)](2)·10H2O (en=ethylenediamine and H4pdta=1,3-propylenediamine-N,N,N',N'-tetraacetic acid) was synthesized, meanwhile its molecular and crystal structures were determined by single-crystal X-ray diffraction technology. The interaction between [Y(III)(pdta)(H2O)]2(2-) and bovine serum albumin (BSA) was investigated by UV-vis and fluorescence spectra. The results indicate that [YIII(pdta)(H2O)]2(2-) quenched effectively the intrinsic fluorescence of BSA via a static quenching process with the binding constant (Ka) of the order of 10(4). Meanwhile, the binding and damaging sites to BSA molecules were also estimated by synchronous fluorescence. Results indicate that the hydrophobic environments around Trp and Tyr residues were all slightly changed. The thermodynamic parameters (ΔG=-25.20 kJ mol(-1), ΔH=-26.57 kJ mol(-1) and ΔS=-4.58 J mol(-1) K(-1)) showed that the reaction was spontaneous and exothermic. What is more, both ΔH and ΔS were negative values indicated that hydrogen bond and Van der Waals forces were the predominant intermolecular forces between [YIII(pdta)(H2O)]2(2-) and BSA.

Multifunctional nanocomposites of superparamagnetic (Fe3O4) and NIR-responsive rare earth-doped up-conversion fluorescent (NaYF4 : Yb,Er) nanoparticles and their applications in biolabeling and fluorescent imaging of cancer cells.

A new kind of magnetic/luminescent multifunctional nanoparticles was synthesized by covalently linking multiple carboxyl-functionalized superparamagnetic Fe(3)O(4) nanoparticles and individual amino-functionalized silica-coated fluorescent NaYF(4) : Yb,Er up-conversion nanoparticles (UCNPs). The resultant nanocomposites bear active carboxylic and amino groups on the surface that were proved to be chemically active and useful for further facile bioconjugation with biomolecules. The UCNPs in the nanocomposite particles can emit visible light in response to the irradiation by near infrared (NIR) light, enabling the application of the nanocomposites in bioimaging. X-Ray diffraction, infrared spectroscopy, transmission electron microscopy, luminescence spectroscopy, and magnetometry were applied to characterize the multifunctional nanocomposites. The nanocomposites exhibited good superparamagnetic and excellent green up-conversion photoluminescent properties that can be exploited in magnetic separation and guiding as well as bioimaging. Due to the presence of active functional groups on the nanocomposite surface, the Fe(3)O(4)/NaYF(4) : Yb,Er magnetic/luminescent nanocomposites were successfully conjugated with a protein called transferrin, which specifically recognizes the transferrin receptors overexpressed on HeLa cells, and can be employed for biolabeling and fluorescent imaging of HeLa cells. Because NIR light can penetrate biological samples with good depth without damaging them and can avoid autofluorescence from them, the presence of both NIR-responsive UCNPs and superparamagnetic nanoparticles in the nanocomposite particles will enable the practical application of the nanocomposites in bioimaging and separation.

Spectrometric studies on the sonodynamic damage of protein in the presence of levofloxacin.

Taking bovine serum albumin (BSA) as typical molecules, the sonodynamic damage of protein in the presence of Levofloxacin (LVFX) and its mechanism were studied by fluorescence and UV-vis spectra. Various influencing factors such as ultrasonic irradiation time, pH value, ionic strength and solution temperature on the damage of BSA were also discussed. The results showed that ultrasound can enhance the damage of LVFX on BSA. The damage degree of BSA was aggravated with the increase of ultrasonic irradiation time, solution temperature and ionic strength, whereas decreased with the increase of solution pH value. Furthermore, the reactive oxygen species (ROS) in reaction system were studied by oxidation and extraction photometry. Experimental results showed that the amounts of superoxide anion radical (·O(2)(-)) and hydroxyl radical (·OH) were significantly more than that of singlet oxygen ((1)O(2)) in the presence of LVFX under ultrasonic irradiation.