Synthesis and Application of Water-Soluble Oxazine Dyes for Detection of PHAs-Producing Bacteria.

Derivatives of oxazine dyes were synthesized on mulitigram scales via efficient synthetic strategies. One practical route was selected to prepare compounds 6, 9 and 10, especially water-soluble compound 6 was obtained in better yield than reported, and compound 10 was insoluble in aqueous media in absence of phenolic-OH. Compounds 3 and 9 were found to be clear pH-dependent between pH = 4.0 and 10.0, and could be used as acid-base indicators to measure intracellular pH. Compounds 6, 9, 10 all have carboxylic acid functionalities, which could be activated and used to conjugate the dyes to biomolecules. In addition, compounds 6 and 9 with good solubility in aqueous media were used to develop a simple, quick, safe, highly sensitive staining method to detect PHAs-producing bacteria on heat-fixed smears, which was confirmed by fluorescence images of PHAs granules of bacteria.

Dual-stimuli responsive and reversibly activatable theranostic nanoprobe for precision tumor-targeting and fluorescence-guided photothermal therapy.

The integrated functions of diagnostics and therapeutics make theranostics great potential for personalized medicine. Stimulus-responsive therapy allows spatial control of therapeutic effect only in the site of interest, and offers promising opportunities for imaging-guided precision therapy. However, the imaging strategies in previous stimulus-responsive therapies are 'always on' or irreversible 'turn on' modality, resulting in poor signal-to-noise ratios or even 'false positive' results. Here we show the design of dual-stimuli-responsive and reversibly activatable nanoprobe for precision tumour-targeting and fluorescence-guided photothermal therapy. We fabricate the nanoprobe from asymmetric cyanine and glycosyl-functionalized gold nanorods (AuNRs) with matrix metalloproteinases (MMPs)-specific peptide as a linker to achieve MMPs/pH synergistic and pH reversible activation. The unique activation and glycosyl targetibility makes the nanoprobe bright only in tumour sites with negligible background, while AuNRs and asymmetric cyanine give synergistic photothermal effect. This work paves the way to designing efficient nanoprobes for precision theranostics.

Irradiated VEGF164-modified tumor cell vaccine protected mice from the parental tumor challenge.

Vascular endothelial growth factor (VEGF) is an important regulating molecule of angiogenesis in tumor formation and progression. Cancer cells always secrete VEGF to stimulate angiogenesis that facilitate growth and invasion of the tumor. In this study, we established a VEGF164 overexpressing LL/2 lung cancer cell model and found that the postirradiated VEGF164-modified tumor cells protected the host against the challenge with LL/2 wild-type tumor cells. Histochemical assay showed that there were large areas of tumor necrosis with macrophage infiltration in the mice vaccinated with the VEGF164-modified tumor vaccine. T-cells isolated from the vaccinated mice showed cytotoxicity against the parental tumor cells in a dose-dependent manner. Meanwhile, sera from the mice vaccinated with LL/2-VEGF164 showed higher titers of antibodies against parental tumor cells compared with the nonvaccinated groups. Our results indicated that VEGF164-modified tumor vaccine could modulate host antitumor immune response and hold therapeutic potential for cancer.

A rhodamine derivative as selective fluorescent and colorimetric chemosensor for mercury (II) in buffer solution, test strips and living cells.

In this paper, we reported a new rhodamine derivative bearing 2,4-dichloroquinazoline as a selective fluorescent chemosensor for Hg(2+). The ring-opening process of spirolactam enabled the large fluorescent enhancement and colorimetric change by Hg(2+) induced configuration transformation of the rhodamine. Moreover, the fluorescence changes of the chemosensor were dramatically specific for Hg(2+) in the presence of other metal ions, which could meet the selective requirements for practical application. Under optimized experimental conditions, the linear response range covered the concentration range of Hg(2+) from 0 to 1.0×10(-6)M, and the limit of detection was calculated to be 2.7×10(-8)M. In addition, the probe was also successfully applied to the determination of Hg(2+) in water samples, test strips and living cells.

Design, synthesis and biological activity evaluation of desloratadine analogues as H1 receptor antagonists.

A series of N-substituted desloratadine analogues were designed and synthesized. They were tested for H1 antihistamine activity by inhibiting histamine-induced contraction of isolated ileum muscles of guinea-pigs in vitro and inhibiting histamine-induced asthmatic reaction in guinea-pigs in vivo. All the evaluated compounds exhibited significant antihistamine activity compared with desloratadine. Five active compounds induced no sedative effects on mouse and four of them exhibited lower anticholinergic side effects than desloratadine. Among these analogues, compound 10, (1S,4S)-4-chlorocyclohexyl desloratadine displayed the highest activity and best safety profile. And it was believed to be a potential candidate as the 3rd generation antihistamine.

Design, synthesis and antihistamine evaluations of several N-hydroxyalkyl desloratadine analogues.

Several N-hydroxyalkyl desloratadines and N-methoxyl ethyl desloratadine were prepared and evaluated for H1 antihistamine activity. The effects on isolated ileum smooth muscle tension in guinea pigs in vitro and asthma-relieving effects on the histamine-induced asthmatic reaction in guinea-pigs in vivo were examined. Most of them exhibited satisfactory H1 antihistamine activity and were obviously more potent than loratadine. Among these, Compound 3, N-(3-hydroxy)propyl desloratadine was the most active one. And it was chosen as a candidate for evaluation of acute toxicity (LD(50)= 0.876(0.784-0.980) g/kg), significantly superior to that of desloratadine (LD(50)=0.353 g/kg). Meanwhile, the experimental results demonstrated that the oxygen atom in the side carbon chain is crucial for enhancing the antihistamine activities.

Synthesis and antihistamine evaluations of novel loratadine analogues.

A series of loratadine analogues containing hydroxyl group and chiral center were synthesized. The effect of the synthesized compounds on the histamine-induced contractions of guinea-pig ileum muscles was studied. In addition, the in vivo asthma-relieving effect of the analogues in the histamine induced asthmatic reaction in guinea-pigs was determined. Most of the compounds exhibited definite H(1) antihistamine activity. The S-enantiomers, compounds 2, 4 and 8, are more potent than the R-enantiomers, compounds 1, 3 and 7. Compound 6 was the most active one among the eight synthesized compounds.

Spectrofluorimetric determination of trace nitrite with a novel fluorescent probe.

A simple, sensitive and selective fluorimetric determination for trace nitrites was developed using an unsymmetrical rhodamine with a high fluorescence quantum yield and large Stokes shift. The method is based on the reaction of the unsymmetrical rhodamine with nitrite in an acidic medium to form a nitroso product, which has much lower fluorescence because the electron-withdrawing effect of the nitroso group influences the system of p-pi conjugation between N atom and benzene ring. Under optimum conditions, the fluorescence quenching intensity is linear over a nitrite concentration range of 1.0 x 10(-8) to 3.5 x 10(-7)M. The detection limit is 2.0 x 10(-10)M (S/N=3). The method was applied to the determination of nitrite in tap water and lake water with satisfactory results. The mechanism for the reaction is also reported.

pH fluorescent probes: chlorinated fluoresceins.

A series of regiospecific chlorinated fluoresceins have been synthesized by the reaction of the regiospecific chlorinated resorcinols with chlorinated phthalic anhydride. The regioisomers were successfully separated by chromatography. The photophysical properties of the obtained chlorinated fluoresceins were examined and found their absorption and emission maxima at long wavelength with high fluorescence quantum yield. Especially, pH-dependent properties of chlorinated fluoresceins have been studied in detail. These compounds show strongly pH-sensitive range of 3.5-7.0, and have lower pK (a) values than fluorescein. Furthermore, their fluorescent intensity could reach the maximum in the physiological environment of pH range 6.8-7.4. Due to higher fluorescence quantum yield and lower pK (a) values, chlorinated fluoresceins will be expected to be used as excellent pH fluorescent probes for pH measurement of the acidic cell.

New fluorescent labels: 4- and 7-chlorofluorescein.

A new mixture of 4- and 7-chlorofluorescein were synthesized by condensation of resorcinol with 3-chlorophthalic anhydride in the presence of methanesulfonic acid or zinc chloride. These regioisomers were successfully separated by chromatography. The photophysical properties were examined and their absorption and emission maxima at long wavelength, high fluorescence quantum yield, and narrow emission bandwidth were found, highly favorable for detecting multiple target substances in the same sample. Furthermore, 4(7)-chlorofluorescein was found to be strongly pH-dependent between 4.0 and 8.0, and could be used as pH-sensitive fluorescent probe to measure intracellular pH.