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Biomedical subjects

Tao Yi

Publications and source records attributed to Tao Yi.

At least 19 recordsLinked to original sources

Morphology-tunable and photoresponsive properties in a self-assembled two-component gel system.

Photoresponsive C3-symmetrical trisurea self-assembling building blocks containing three azobenzene groups (LC10 and LC4) at the rim were designed and synthesized. By introducing a trisamide gelator (G18), which can self-aggregate through hydrogen bonds of acylamino moieties to form a fibrous network, the mixture of LC10 (or LC4) and G18 forms an organogel with coral-like supramolecular structure from 1,4-dioxane. The cooperation of hydrogen bonding and the hydrophobic diversity between these components are the main contributions to the specific superstructure. The two-component gel exhibits reversible photoisomerization from trans to cis transition without breakage of the gel state.

Journal Article↗

Modulation of the photochromic property in an organoboron-based diarylethene by a fluoride ion.

Organoboron-based diarylethene was successfully synthesized and exhibited photochromic property. Furthermore, its photochromic property can be modulated by a fluoride ion. The absorption maximum of the photostationary state shifted from 655 to 490 nm upon addition of a fluoride ion. The modulation mechanism is attributed to the special Lewis acid-base interaction between a trivalent boron atom and a fluoride ion.

Journal Article↗

Series of new cationic iridium(III) complexes with tunable emission wavelength and excited state properties: structures, theoretical calculations, and photophysical and electrochemical properties.

A series of new cationic iridium(III) complexes [Ir(piq)2(N/\N)]+PF6- (1-6) (piq =1-phenyl-isoquinoline) containing N/\N ligands with different conjugated lengths were synthesized, where the six N/\N ligands were bipyridine, phenanthroline, 2-pyridyl-quinoline, 2,2'-biquinoline, 1,1'-biisoquinoline, and 2-(2-quniolinyl)quinoxaline. Single-crystal X-ray diffraction spectra of three complexes were studied, and the iridium(III) centers were found to adopt a distorted octahedral coordination geometry with cis metalated carbons and trans nitrogen atoms. UV-vis, photoluminescence, cyclic voltammetry, and theoretical calculations were employed for studying the photophysical and electrochemical properties. And the excited-state properties were investigated in detail. The excited state of complexes is complicated and contains triplet metal-to-ligand charge transfer (3MLCT), triplet ligand-to-ligand charge transfer (3LLCT), and ligand-centered (cyclometalated) (3LC) transitions simultaneously. Importantly, the emission wavelength can be tuned significantly from 586 to 732 nm by changing the conjugated length of N/\N ligands.

Journal Article↗

Polyaryl ether dendrimer with a 4-phenylacetyl-5-pyrazolone-based terbium(III) complex as core: synthesis and photophysical properties.

A series of novel dendritic beta-diketone ligands, 1-phenyl-3-[G-n]-4-phenylacetyl-5-pyrazolone (n = 0-3, G stands for polyaryl ether), were synthesized by introducing Fréchet-type dendritic branches. The corresponding Tb3+-cored dendritic complexes were characterized by X-ray crystallography, elemental analysis, ESI mass spectra, and FT-IR spectra. These dendritic complexes, prepared from aqueous solution, exhibit high stability. Interestingly, the study of photophysical properties shows that the luminescence quantum yields of the dendritic Tb-complexes increase from 0.1 to 2.26% with an increase of the dendritic generation from 0 to 3. Importantly, an "energy-reservoir effect" was observed in the dendritic system using the method based on the resonance energy transfer from these complexes to rhodamine 6G. With the increase of the dendritic generation, the metal-centered luminescence quantum yield was almost the same, and the energy transfer (phi(transfer)) from the ligand to Tb(3+) increased. Further measurements of the triplet state and oxygen quenching of these dendritic complexes verify that this enhancement of the energy transfer (phi(transfer)) is attributed to both an "antenna effect" and a "shell effect".

Journal Article↗

Simultaneous qualitative and quantitative analyses of the major constituents in the rhizome of Ligusticum Chuanxiong using HPLC-DAD-MS.

An HPLC-DAD-MS method was developed for the qualitative and quantitative analysis of the major constituents in Chuanxiong (the dried rhizome of Ligusticum chuanxiong Hort). Twenty compounds including phenolic constituents, alkylphthalides and phthalide dimers were identified using online ESI-MS and comparisons with literature data and standard compounds, and six of them were quantified by HPLC-DAD simultaneously. A comprehensive validation of the method including sensitivity, linearity, repeatability and recovery was conducted. The linear regressions were acquired with R(2) > 0.99 and limit of detection (LOD, S/N = 3) values were between 1.5 and 2.5 ng. The repeatability was evaluated by intra- and inter-day assays, and relative standard deviation (RSD) values were reported within 1.87%. The recovery studies for the quantified compounds were observed in the range of 96.36-102.37% with RSD values less than 2.63%. These phenolic constituents and alkylphthalides, the major constituents in Chuanxiong, are generally regarded as the index for the quality assessment of this herb. The overall procedure is accurate and reproducible, which is considered suitable for the qualitative and quantitative analyses of a large number of Chuanxiong samples.

Calibration↗

Determination of phenytoin sodium injection and tablets by highly accurate nephelometric titration.

A highly accurate nephelometric titration method was developed for the quantitative analysis of phenytoin sodium injection and tablets. The titration operating conditions and the validation of the method were studied. Five batches of phenytoin sodium injection and tablets were determined by the proposed method and the control experiment methods, respectively. The results of the titration are comparable to those of control experiments. The proposed method is accurate and reproducible, which is considered suitable for the quantitative analysis of a large number of samples.

Anticonvulsants↗

Application of highly accurate nephelometric titration in the assaying of phenytoin sodium.

AIM: To determine phenytoin sodium by a highly accurate nephelometric titration. METHODS: The titration operating conditions were optimized and the solubility product constant of phenytoin silver precipitation was determined. RESULTS: The result of the titration is comparable to those of control experiments. CONCLUSION: The proposed method has been found to be accurate, precise, specific, reproducible, and linear.

Nephelometry and Turbidimetry↗

Tuning the triplet energy levels of pyrazolone ligands to match the 5D0 level of europium(III).

Three pyrazolone-based ligands, namely 1-phenyl-3-methyl-4-(1-naphthoyl)-5-pyrazolone (HL1), 1-phenyl-3-methyl-4-(4-dimethylaminobenzoyl)-5-pyrazolone (HL2), and 1-phenyl-3-methyl-4-(4-cyanobenzoyl)-5-pyrazolone (HL3), were synthesized by introducing electron-poor or electron-rich aryl substituents at the 4-position of the pyrazolone ring. Their corresponding europium complexes Eu(LX)3(H2O)2 and Eu(LX)3(TPPO)(H2O) (X = 1-3) were characterized by photophysical studies. The characteristic Eu(III) emission of these complexes with at most 9.2 x 10(-3) of fluorescent quantum yield was observed at room temperature. The results show that the modification of ligands tunes the triplet energy levels of three pyrazolone-based ligands to match the 5D0 energy level of Eu3+ properly and improves the energy transfer efficiency from antenna to Eu3+, therefore enhancing the Eu(III) emission intensity. The highest energy transfer efficiency and probability of lanthanide emission of Eu(L1)3(H2O)2 are 35.1% and 2.6%, respectively, which opens up broad prospects for improving luminescent properties of Eu(III) complexes by the modification of ligands. Furthermore, the electroluminescent properties of Eu(L1)3(TPPO)(H2O) were also investigated.

Chemistry, Inorganic↗

Highly selective two-photon chemosensors for fluoride derived from organic boranes.

[reaction: see text] Three organoboron compounds are shown to be two-photon fluorescent sensors for fluoride anion with high sensitivity and selectivity. The recognition mechanism is attributed to the unique steric structure of the bulky dimesitylboryl group and the Lewis acid-base interaction between trivalent boron atom and fluoride anion.

Journal Article↗

Shift multiplexing by planar waveguide referencing.

We present a new method with which to implement shift multiplexing by planar waveguide referencing. In this method, a planar waveguide is used to steer the reference beam, and we implement shift multiplexing by shifting the recording medium. A spatial selectivity as high as 1.1 microm is obtained. By using waveguide referencing we can make a compact and simple holographic system.

Journal Article↗

Identification and comparative determination of senkyunolide A in traditional Chinese medicinal plants Ligusticum chuanxiong and Angelica sinensis by HPLC coupled with DAD and ESI-MS.

Using the HPLC/DAD/ESI/MS method, the qualitative and quantitative analysis of senkyunolide A (SA) in the rhizomes of Ligusticum chuanxiong (Rhizoma chuanxiong; CX) and roots of Angelica sinensis (DG) was established. As a result, it was found that SA is a characteristic standard compound for the quality evaluation and chemical differentiation between CX and DG. Methanol was chosen in the preparation of standard solutions and extraction of samples based on the stability data. The identity of SA in CX and DG was unambiguously determined based on the quasimolecular ions in ESI-MS. A comprehensive validation of the method, including sensitivity, linearity, reproducibility and recovery, was conducted using the optimized chromatographic conditions. The linear calibration curve was acquired with R2>0.999 and limit of detection (S/N=3) was estimated to be 12.5 mug/g. The reproducibility was evaluated by repeated sample injection and replicated analysis of samples with the relative standard deviation (RSD) value found within 0.68%. The recovery rates of SA varied within the range of 96.91-101.50% with RSD less than 2.38%. In the present work, the contents of SA were quantified within 3.94-9.14 mg/g and 0.108-0.588 mg/g for 12 batches each of CX and DG. The results demonstrated that SA is a useful standard compound for the quality evaluation and chemical differentiation between CX and DG. The analytical procedure is precise and reproducible and thus suitable for the analysis of a large number of samples.

Angelica↗

The construction, characterization and transfection of liposome- polycation-CDKN1B plasmid complexes.

OBJECTIVE: To develop an efficient non-viral gene delivery system in order to transfer CDKN1B gene efficiently into lung and liver carcinoma cells. METHODS: A recombinant plasmid composed of CDKN1B sequence and EYFP as reporter gene was constructed and identified. The recombinant DNA was then formulated the lipids-polycation-DNA complexes(LPDs) with protamine sulfate. Several kinds of lung and liver carcinoma cells were transfected by means of LPDs. The physicochemical properties of LPDs were investigated using PCS method and TEM, respectively. The expression of EYFP in A549 cells was observed under fluorescent microscope and evaluated by flow cytometry analysis. Finally, the production of CDKN1B protein in transfected LLC, Chang and 7721 cells was identified by Western blot analysis. RESULTS: The average diameter of the LPDs were 167 nm with the polydispersity index of 0.35. The average zeta potential of LPDs was +32.6 mV. LPDs look like a sunken sphere. The fluoresent microscope picture clearly indicated the expression of EYFP in A549 cells. The flow cytometry result showed that the transfection efficiency of LPDs in A549 cells was comparable with that of LipofectAMINE, the positive control. Western blot analysis confirmed the production of CDKN1B protein in LLC, Chang and 7721 cells transfected with LPDs, while no CDKN1B protein was detected in cells transfected with naked DNA. CONCLUSION: The construction of the recombinant plasmid is successful. LPDs can deliver the recombinant plasmid to lung carcinoma cells and liver carcinoma cells with high efficiency. Therefore, this kind of gene delivery system has the potential uses for the treatment of lung and liver cancer.

Blotting, Western↗

Combination of low-dose cisplatin and recombinant xenogeneic endoglin as a vaccine induces synergistic antitumor activities.

Angiogenesis is critical to the growth and metastasis of solid tumors, and acquired drug resistance is one of the major hindrances to chemotherapy. Thus, we sought a rational strategy using the combination of antiangiogenic biotherapy and chemotherapy for cancer therapy. We explored the efficacy of a strategy combining low-dose cisplatin and a recombinant xenogeneic endoglin as a protein vaccine, which we previously demonstrated to have effective antiangiogenic effects in several mouse models. We found that both low-dosage cisplatin and xenogeneic endoglin vaccine individually resulted in effective suppression of tumor growth in 2 tumor models via inhibition of tumor angiogenesis. Remarkably, the combination therapy resulted in not only significant antiangiogenic effects but also additional promotion of tumor cell apoptosis and inhibition of tumor cell proliferation, without any ensuing increase in host toxicity during the course of treatment, which lasted for 6 months. In addition, the combination demonstrated a synergistic relationship, which was shown in all of the synergistic indexes, i.e., tumor volume, angiogenesis, apoptosis and proliferation. Both antibodies and antibody-producing B cells against mouse self-endoglin were observed in all mice immunized by the xenogeneic endoglin vaccine (alone and combination), which suggested that low-dose cisplatin did not suppress the host immune response but potentiated the antitumor activity of the xenogeneic endoglin vaccine. These observations may provide the basis for an effective alternative strategy for cancer therapy in the near future.

Animals↗

Induction of apoptosis and tumor regression by vesicular stomatitis virus in the presence of gemcitabine in lung cancer.

Vesicular stomatitis virus (VSV) has been shown to replicate rapidly in vitro and kill selectively a variety of tumor cell lines. The present study was designed to determine whether gemcitabine potentiates the antitumor activity of VSV in vitro and in vivo. A549 human lung adenocarcinoma cells and LLC Lewis lung carcinoma cells were treated with VSV (0.1-10 plaque-forming units per cell) plus gemcitabine (20 nM to 20 microM). Mice bearing A549 or LLC were treated with VSV (5 x 10(4) to 1 x 10(8) plaque-forming units) daily for 5 days plus gemcitabine (5-125 mg/kg/day) once every 3 days for 4 times. Induction of apoptosis and effects on growth inhibition were assessed. The lung cancer cells treated with VSV plus gemcitabine displayed the apparently increased apoptotic cells compared with treatment with VSV or gemcitabine alone. The combined treatment with VSV plus gemcitabine induced the apparent antitumor activity with complete regression of the established lung cancer in both A549 and LLC lung cancer models and augmented the induction of apoptosis in lung cancer cells in vivo as well. This study suggests that the combined treatment with VSV plus gemcitabine may augment the induction of apoptosis in lung cancer cells in vitro and in vivo, and that the augmented antitumor activity in vivo may result from the increased induction of apoptosis in lung cancer cells. The present findings may be of importance to the further exploration of the potential application of this combined approach in the treatment of lung cancer.

Adenocarcinoma↗

Active immunotherapy of tumors with a recombinant xenogeneic endoglin as a model antigen.

Angiogenesis play a critical role in tumor growth and metastasis. Increasing evidence suggests that endoglin is a powerful marker of angiogenesis in solid malignancies. Thus, breaking of immune tolerance of self-endoglin-associated angiogenesis is an attractive approach to cancer therapy. To test this concept, we recombined the extracellular domains of porcine endoglin, and used it as a xenogeneic vaccine. We found that immunotherapy with porcine endoglin was effective at both protective and therapeutic anti-tumor immunity in several mouse tumor models. Autoantibodies against mouse endoglin were identified by Western blot and ELISA. IgG1 and IgG2b were substantially increased. Anti-endoglin antibody-producing B cells were detectable by ELISPOT assay. There was endothelial deposition of immunoglobulins within tumors. The anti-tumor activity was also induced by the adoptive transfer of the purified immunoglobulins. Angiogenesis was apparently inhibited within the tumor tissues and on the alginate beads. The increased apoptotic cells were found within the tumor tissues from the mice treated with porcine endoglin. The anti-tumor activity and production of autoantibodies against mouse endoglin could be abrogated by depletion of CD4(+) T lymphocytes. Remarkably, no marked toxicity was found in the immunized mice. These observations may provide an alternative rational strategy for active cancer immunotherapy.

Adoptive Transfer↗

Highly accurate nephelometric titrimetry.

A method that accurately indicates the end-point of precipitation reactions by the measurement of the relative intensity of the scattered light in the titrate is presented. A new nephelometric titrator with an internal nephelometric sensor has been devised. The work of the titrator including the sensor and change in the turbidity of the titrate and intensity of the scattered light are described. The accuracy of the nephelometric titrimetry is discussed theoretically. The titration of NaCl with AgNO(3) serves as a model. A relative error as well as deviation is within 0.2% under the experimental conditions. The applicability of the titrimetry in pharmaceutical analyses, for example, phenytoin sodium and procaine hydrochloride, is generally illustrated.

Chemistry, Pharmaceutical↗

[Constructing the tumor cell vaccine based on homologous matrix metalloproteinase-2 and exploring its effects].

OBJECTIVE: To construct the tumor cell vaccine based on homologous matrix metalloproteinase-2 (MMP-2), and explore its anti-tumor effects. METHODS: The tumor cell vaccine was constructed by transfecting chicken MMP-2 to tumor cells. MTT colorimetric assay was used to evaluate the activation of the transfectants. Then we observed the formative tumor response in vivo and evaluated the effects of the tumour cell vaccine in immunized mice rechallenged with parental cells. RESULTS: Using RT-PCR, we picked out the cell strain with the highest expression level from the transfectants. The MTT colorimetric assay revealed that the transfectants increased the expression of the MMP-2 of tumor cells while they did not change the trend of tumor cells' growth. And in animal experiments the vaccine was preliminarily found to be effective for inhibiting the tumour growth and prolonging the survival time of animals. CONCLUSION: We have constructed the tumor cell vaccine based on homologous matrix metalloproteinase-2. The experiments demonstrated that breaking the immune tolerance of MMP-2 by means of active immunity should be a useful approach to cancer therapy.

Adenocarcinoma↗

[Construction of pcDNA-BLC and expression of BLC in tumor cells].

OBJECTIVE: To establish a stable transformants of B-lymphocyte chemoattractant (BLC) with the eukaryotic expression vector for investigation of its anti-tumor function further. METHODS: The BLC full-length cDNA was amplified by RT-PCR from the total RNA isolated from the spleen of mouse. After sequence determination, the BLC full-length cDNA was cloned into the eukaryote expression vector pcDNA3.1 (+), the resulted recombinant was designated as pcDNA-BLC. Then pcDNA-BLC was transfected into murine tumor cell line colon 26 by LIPOFECTIN. The stable transformants were selected by G418 and identified by immunoblot assay. The bioactivity of BLC was confirmed by chemotaxis assay. RESULTS: The recombinant pcDNA-BLC was successfully constructed. The stable transformants of BLC can express the bioactive BLC in tumor cell lines. CONCLUSION: The stable transformants can stably express BLC in tumor cell lines. These stable transformants will be useful for further study of the BLC biological effect on tumor and for the development of cancer vaccine.

Adenocarcinoma↗