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A novel triphenylamine derivative, 4,4′-bis-([1,10]phenanthrolin-2-yl) imidazo -triphenylamine (IPTPA) with an A-π-D-π-A structure, has been synthesized and characterized. The UV absorption, single and two-photon fluorescence spectra showed that IPTPA was highly sensitive to Ag+ with a lower detection limit of 3.97 nmoL/L and a moderate binding constant of 2.16 × 105/M at room temperature. The two-photon active cross-section of IPTPA was calculated with a value of 94.68 GM at 800 nm in the tris-HCl buffer solution. The binding mechanism between IPTPA and Ag+ were explored by the Job plot, ESI-MS and 1H NMR. The A-π-D-π-A structure of IPTPA was substituted by the A-π-D-π-D structure of IPTPA-Ag to improve the fluorescence. Furthermore, the fluorescence microscopy images indicated that IPTPA could detect Ag+ in living cells.

In recent years, conjugated polymers (CPs) and their nanoparticles (CPNs) were widely concerned and applied in many fields due to their outstanding advantages such as higher absorption coefficients, good photostability, low toxicity and good biocompatibility. However, most reports were focused on their applications, and rare attentions were given on the synthesis of CPs and the effect factors of CPNs’ morphology and properties. In this work, four CPs (P1, P2, P3, P4) with different length side chains were synthetized by Wittig–Horner reaction and further used to prepare CPNs by the nano-precipitation method. The CPs and CPNs were characterized and analyzed by Hydrogen Nuclear Magnetic Resonance (1H NMR), gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and transmission electron microscope (TEM). The absorbance and fluorescence emission spectra of CPs in tetrahydrofuran (THF) and CPNs solutions with different length side chains were investigated, and their quantum yields (Фs) were calculated by the reference method. The results showed that the synthetic CPs have narrow polydispersity index. Some interesting phenomenon appeared with the increased side chain length. The molecular weights will reduce except P3, and the absorbance and fluorescence emission spectra of CPs and CPNs are red-shifted. Фs are better and enlarged for CPs and CPNs, and better dispersion and uniform size were founded with longer side chains.

Toxoplasma gondii has a complex life cycle and pathogenic mechanisms. Acute T. gondii infections in mice often result in death, whereas in chronic infections, the parasites may persist in the host tissues as intraneuronal or intramuscular cysts. However, the virulence of T. gondii strains in mice varies with its genetic background. The present study investigated the pathogenicity and pathological lesions of two T. gondii isolates from China: namely, TgCatCHn2 (ToxoDB#17) and TgCatCHn4 (ToxoDB#9). The virulent (ToxoDB#216) and avirulent (VEG) strains were employed as controls. Toxoplasmosis was induced by inoculating BALB/c mice with oocysts of the strains of T. gondii VEG, ToxoDB#216, TgCatCHn2 (ToxoDB#17), and TgCatCHn4 (ToxoDB#9), respectively. As a result, one oocyst of ToxoDB#216 could kill a mouse within 10 days post inoculation (DPI). The survival time of the mice for T. gondii TgCatCHn2 and TgCatCHn4 was >60 DPI for 106/mL oocysts, but this concentration (106/mL oocysts) of VEG strain could kill mice within 11 DPI. Compared with the strains of T. gondii ToxoDB#216 and VEG, the lesions in the small intestines of the strains of TgCatCHn2- and TgCatCHn4-infected mice were significantly smaller (P 0.05). However, the granules in the PCs showed negative lysozyme expression in the intestines of mice infected with T. gondii TgCatCHn2 and TgCatCHn4. Thus, T. gondii strains of TgCatCHn2 (ToxoDB#17) and TgCatCHn4 (ToxoDB#9) were avirulent strains, they triggered an inhibition of lysozyme expression in the granules of PCs of the mouse intestine. These effects may in turn lead to intestinal dysbiosis, which may be related to further parasitic invasion of the intestines. The findings of the present study further expand the spectrum of the pathogenic features of various Chinese isolates of T. gondii.