The complete plastid genome of Phoenix canariensis Chabaud (Arecaceae) and phylogenetic analysis.

Phoenix canariensis Chabaud is a vital ornamental and widely planted in the urban landscape of China. In this study, we reported the complete chloroplast genome (cpDNA) of P. canariensis, which is 158,477 bp in length, including a large single copy region (LSC) of 86,189 bp, a small single copy region (SSC) of 17,704 bp, and a pair of inverted repeats (IR) regions of 27,292 bp inserted between LSC and SSC. 132 genes are encoded, including 86 protein-encoding genes, 8 ribosomal RNA genes, and 38 transfer RNA genes. The overall GC content of the chloroplast genome is 37.22%, wherein the corresponding values in the LSC, SSC, and IR regions are 35.3%, 30.79%, and 42.35%, respectively. Phylogenetic analysis showed that P. canariensis is sister to P. dactylifera with strong bootstrap support.

Synthesis of CdTe quantum dot-conjugated CC49 and their application for in vitro imaging of gastric adenocarcinoma cells.

The purpose of this experiment was to investigate the visible imaging of gastric adenocarcinoma cells in vitro by targeting tumor-associated glycoprotein 72 (TAG-72) with near-infrared quantum dots (QDs). QDs with an emission wavelength of about 550 to 780 nm were conjugated to CC49 monoclonal antibodies against TAG-72, resulting in a probe named as CC49-QDs. A gastric adenocarcinoma cell line (MGC80-3) expressing high levels of TAG-72 was cultured for fluorescence imaging, and a gastric epithelial cell line (GES-1) was used for the negative control group. Transmission electron microscopy indicated that the average diameter of CC49-QDs was 0.2 nm higher compared with that of the primary QDs. Also, fluorescence spectrum analysis indicated that the CC49-QDs did not have different optical properties compared to the primary QDs. Immunohistochemical examination and in vitro fluorescence imaging of the tumors showed that the CC49-QDs probe could bind TAG-72 expressed on MGC80-3 cells.

The conjugates of gold nanorods and chlorin e6 for enhancing the fluorescence detection and photodynamic therapy of cancers.

Gold nanorods (AuNRs) were conjugated with chlorin e6 (Ce6), a commonly used photosensitizer, to form AuNRs-Ce6 by electrostatic binding. Due to the strong surface plasmon resonance coupling, the fluorescence of conjugated Ce6 was enhanced 3-fold and the production of singlet oxygen was increased 1.4-fold. AuNRs-Ce6 were taken up by the HeLa and KB cell lines more easily than free Ce6, enhancing the intracellular delivery of Ce6. The increased cellular amount of Ce6 leads to a 3-fold more efficient photodynamic killing of these two cell lines. This demonstrates the potential of this approach to improve photodynamic detection and therapy of cancers.

In vitro gastric cancer cell imaging using near-infrared quantum dot-conjugated CC49.

In this experiment, we developed a bioprobe label for immunofluorescence using gastric tumor-specific quantum dots (QDs) to detect gastric tumor cells in vitro. The fluorescent probe, which is capable of specifically labeling gastric tumor cells, was constructed by taking advantage of the unique and superior properties of QDs. We grafted primary QDs onto the tumor-associated glycoprotein 72 (TAG-72) monoclonal antibody CC49 to produce CC49-QDs that specifically label tumor cells. Following a series of tests on the diameter and emission spectrum of CC49-QDs, they were employed in immunofluorescence analysis. Transmission electron microscopy and fluorescence spectrum analyses indicated that CC49-QDs had a 0.25 nm higher average diameter than the primary QDs, and that the grafted CC49 had no difference in optical properties compared to the primary QDs. In cell imaging, the cells labeled with CC49-QDs generated brighter fluorescence compared with the cells of the primary QD group. The results of immunofluorescence analysis demonstrated that antibody grafting reinforced the specific binding of QDs to tumor cells. This probe may also be further applied to live gastric cancer animal models to track lymphatic metastasis. In addition, it may potentially offer theoretical support for lymphadenectomy in the treatment of gastric cancer.

Liposome encapsulation of thiol-capped CdTe quantum dots for enhancing the intracellular delivery.

Although water soluble thiol-capped quantum dots (QDs) have been widely used as photoluminescence (PL) probes in various applications, the negative charges on thiol terminals limit the cell uptake hindering their applications in cell imaging. The commercial liposome complex (Sofast®) was used to encapsulate these QDs forming the liposome vesicles with the loading efficiency as high as about 95%. The cell uptakes of unencapsulated QDs and QD loaded liposome vesicles were comparatively studied by a laser scanning confocal microscope. We found that QD loaded liposome vesicles can effectively enhance the intracellular delivery of QDs in three cell lines (human osteosarcoma cell line (U2OS); human cervical carcinoma cell line (Hela); human embryonic kidney cell line (293 T)). The photobleaching of encapsulated QDs in cells was also reduced comparing with that of unencapsulated QDs, measured by the PL decay of cellular QDs with a continuous laser irradiation in the microscope. The flow cytometric measurements further showed that the enhancing ratios of encapsulated QDs on cell uptake are about 4-8 times in 293 T and Hela cells. These results suggest that the cationic liposome encapsulation is an effective modality to enhance the intracellular delivery of thiol-capped QDs.

Study on the intracellular fate of Tat peptide-conjugated quantum dots by spectroscopic investigation.

The photoluminescence (PL) spectrum of water-soluble thiol-capped CdTe quantum dots (QDs) conjugated with Tat peptide in solution showed a remarkable redshift as compared to that of unconjugated QDs. After cellular uptake of the Tat-QDs conjugates, the micro-PL spectrum of Tat-QDs in lysosomes showed a spectral blueshift, which was most probably due to the fact that Tat peptide was digested by the enzymes, leaving the Tat-detached QDs in lysosomes. The reasons for the spectral changes have been discussed in detail.

Multi-functional thermosensitive composite microspheres with high magnetic susceptibility based on magnetite colloidal nanoparticle clusters.

Monodisperse organic/inorganic composite microspheres with well-defined structure were prepared through the encapsulation of silica coated superparamagnetic magnetite colloidal nanoparticle clusters (CNCs) with cross-linked poly(N-isopropylacrylamide) (PNIPAM) shell. At first, the sub-micrometer-sized CNCs were fabricated by the solvothermal process, and then a silica layer was coated on the surface of CNCs through a sol-gel process, and finally, a thermoresponsive shell of PNIPAM was deposited onto the surface of the core/shell magnetic microspheres by a precipitation polymerization. The experimental results showed that the size of Fe(3)O(4) core, the thickness of SiO(2) shell, as well as volume phase transition temperature (VPTT) of PNIPAM shell could be well controlled, and this structured modulation could satisfy different requirements. The superparamagnetic behavior, high magnetization (the saturation magnetization of Fe(3)O(4)/SiO(2)/PNIPAM microspheres with a 10% cross-linking density is 41.6 emu/g), and good thermosensitivity make these composite microspheres an ideal candidate for various important applications such as in controlled drug delivery, bioseparation, and catalysis.

Thiol-capped CdTe quantum dots with two-photon excitation for imaging high autofluorescence background living cells.

To effectively image living cells with quantum dots (QDs), particularly for those cells containing high content of native fluorophores, the two-photon excitation (TPE) with a femto-second 800 nm laser was employed and compared with the single-photon excitations (SPE) of 405 nm and 488 nm in BY-2 Tobacco (BY-2-T) and human hepatocellular carcinoma (QGY) cells, respectively. The 405 nm SPE produced the bright photoluminescence (PL) signals of cellular QDs but also induced a strong autofluorescence(AF) from the native fluorophores like flavins in cells. The AF occupied about 30% and 13% of the total signals detected in QD imaging channel in the BY-2-T and QGY cells, respectively. With the excitation of 488 nm SPE, the PL signals were lower than those excited with the 405 nm SPE, although the AF signals were also reduced. The 800 nm TPE generated the best PL images of intracellular QDs with the highest signal ratio of PL to AF, because the two-photon absorption cross section of QDs is much higher than that of the native fluorophores. By means of the TPE, the reliable cellular imaging with QDs, even for the cells having the high AF background, can be achieved.

Photochemical instability of thiol-capped CdTe quantum dots in aqueous solution and living cells: process and mechanism.

The process and mechanism of photochemical instability of thiol-capped CdTe quantum dots (QDs) in aqueous solution were experimentally studied. After laser irradiation, the corresponding Raman bands of the Cd-S bond decreased obviously, indicating bond breaking and thiol detachment from the QD surfaces. Meanwhile, a photoinduced aggregation of QDs occurred with the hydrodynamic diameter increased to hundreds of nanometers from an initial 20 nm, as detected with dynamic light scattering measurements. The bleaching of the photoluminescence of QDs under laser irradiation could be attributed to the enhanced nonradiative transfer in excited QDs caused by increased surface defects due to the losing of thiol ligands. Singlet oxygen (1O2) was involved in the photooxidation of QDs, as revealed by the inhibiting effects of 1O2 quenchers of histidine or sodium azide (NaN3) on the photobleaching of QDs. The linear relationship in Stern-Volmer measurements between the terminal product and the concentration of NaN3 demonstrated that 1O2 was the main pathway of the photobleaching in QD solutions. By comparing the photostability of QDs in C2C12 cells with and without NaN3 treatment, the photooxidation effect of 1O2 on photobleaching of cellular QDs was confirmed.

Time-dependent photoluminescence blue shift of the quantum dots in living cells: effect of oxidation by singlet oxygen.

Time-dependent photoluminescence (PL) enhancement, blue shift, and photobleach were observed from the thiol-capped CdTe quantum dots (QDs) ingested in mouse myoblast cells and human primary liver cancer cells. It was revealed that the PL blue shift resulted from the photooxidation of the QD core by singlet oxygen molecules formed on the QD core surface.

Transfection of mEpo gene to intestinal epithelium in vivo mediated by oral delivery of chitosan-DNA nanoparticles.

AIM: To prepare the chitosan-pmEpo nanoparticles and to study their ability for transcellular and paracellular transport across intestinal epithelia by oral administration. METHODS: ICR mice were fed with recombinant plasmid AAV-tetO-CMV-mEpo (containing mEpo gene) or pCMVbeta(containing LacZ gene), whether it was wrapped by chitosan or no. Its size and shape were observed by transmission electron microscopy. Agarose gel electrophoresis was used to assess the efficiency of encapsulation and stability against nuclease digestion. Before and after oral treatmant, blood samples were collected by retro-orbital puncture, and hematocrits were used to show the physiological effect of mEpo. RESULTS: Chitosan was able to successfully wrap the plasmid and to protect it from DNase degradation. Transmission electron microscopy showed that freshly prepared particles were approximately 70-150 nm in size and fairly spherical. Three days after fed the chitosan-pCMVbeta complex was fed, the mice were killed and most of the stomach and 30% of the small intestine were stained. Hematocrit was not modified in naive and 'naked' mEpo-fed mice, a rapid increase of hematocrit was observed during the first 4 days of treatment in chitosan-mEpo-fed animals, reaching 60.9+/-1.2% (P<0.01), and sustained for a week. The second feed (6 days after the first feed) was still able to promote a second hematocrit increase in chitosan-mEpo-fed animals, reaching 65.9+/-1.4% (P<0.01), while the second hematocrit increase did not appear in the 'naked' mEpo-second-fed mice. CONCLUSION: Oral chitosan-DNA nanoparticles can efficiently deliver genes to enterocytes, and may be used as a useful tool for gene transfer.