ABSTRACT
Iron (III) was incorporated, to the surface of a synthesized ZnO, using two nominal molar percentages of Fe (III): 1% and 5% Fe relative to ZnO. Samples dried and calcined at 200⯰C and 400⯰C for 2â¯h, were characterized by XRD, XPS, XRF, N2-adsorption-BET and (UV-vis)-DRS. Photocatalytic activities of the catalysts were assessed based on the degradation of rhodamine B (RhB) and caffeine (CAF) in aqueous solution under two irradiation conditions: UV and visible light illumination. Prior to the photocatalytic tests, the interaction of each one of the substrates with either Fe(III) or Fe(II) was studied in homogeneous medium under UV-illumination and oxygenated environment. It was found that Fe (III) can play an important role in homogeneous media in the photoassisted degradation, both of rhodamine B and caffeine, while Fe (II) does not exert a relevant role in the photoassisted degradation of the referred substrates. Fe-ZnO samples display similar or poorer performance than pure ZnO in the presence of UV light for both studied substrates. The phenomenon can be attributed to the formation of either goethite or ZnFe2O4 at the ZnO surface where the coupled Fe3+/Fe2+ can act as recombination centers for the photogenerated charges. On the contrary, all Fe-ZnO samples showed enhanced photocatalytic activity under visible illumination which seems to be independent of the iron content. In this context, the mechanisms for photoassisted degradation of both the substrates in homogeneous medium and photocatalytic degradation are discussed, as well as the role of Fe in the photodegradation processes.
Subject(s)
Caffeine/chemistry , Ferric Compounds/pharmacology , Photolysis/drug effects , Rhodamines/chemistry , Zinc Oxide/chemistry , Adsorption , Caffeine/radiation effects , Catalysis , Ferric Compounds/chemistry , Iron/chemistry , Light , Rhodamines/radiation effects , Ultraviolet Rays , WaterABSTRACT
Three new gold(I)-coumarin-based trackable therapeutic complexes and two non-trackable analogues have been synthesised and fully characterised. They all display anti-proliferative properties on several types of cancer cell lines, including those of colon, breast, and prostate. Two complexes displayed significant anti-inflammatory effects; one displayed pro-inflammatory behaviour; this highlights the impact of the position of the fluorophore on the caffeine scaffold. Additionally, the three coumarin derivatives could be visualised in vitro by two-photon microscopy.
Subject(s)
Anti-Inflammatory Agents/pharmacology , Antineoplastic Agents/pharmacology , Caffeine/analogs & derivatives , Caffeine/pharmacology , Coordination Complexes/pharmacology , Coumarins/pharmacology , Anti-Inflammatory Agents/chemical synthesis , Anti-Inflammatory Agents/chemistry , Anti-Inflammatory Agents/radiation effects , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Antineoplastic Agents/radiation effects , Caffeine/chemical synthesis , Caffeine/radiation effects , Cell Line, Tumor , Coordination Complexes/chemical synthesis , Coordination Complexes/chemistry , Coordination Complexes/radiation effects , Coumarins/chemical synthesis , Coumarins/chemistry , Coumarins/radiation effects , Fluorescence , Fluorescent Dyes/chemical synthesis , Fluorescent Dyes/chemistry , Fluorescent Dyes/pharmacology , Fluorescent Dyes/radiation effects , Gold/chemistry , HEK293 Cells , Humans , Microscopy, Fluorescence, Multiphoton/methods , Ultraviolet RaysABSTRACT
We investigated electronically excited states of caffeine and its 1:1 complex with water by using resonant two-photon ionization (R2PI) and UV-UV hole-burning techniques. Strong vibronic coupling between a pair of close-lying pi-pi* and n-pi* transitions is proposed to be responsible for the broad spectral feature observed. By comparing the experimental results with those of theoretical calculations, both the O-bonded and N-bonded forms were suggested to be initially produced for the 1:1 complex. The electronic transitions of the O-bonded complex were blueshifted in the R2PI spectrum. For the N-bonded complex, the excited state undergoes an ultrafast decay process, followed by dissociation on a repulsive potential energy surface, which gives rise to a characteristically anomalous cluster distribution in nanosecond experiments.
Subject(s)
Caffeine/chemistry , Caffeine/radiation effects , Models, Chemical , Models, Molecular , Water/chemistry , Computer Simulation , Molecular Conformation/radiation effects , Photons , Ultraviolet RaysABSTRACT
BACKGROUND: Radioimmunotherapy and other forms of biologically targeted radiopharmaceutic treatment appear to show unexpected efficacy in many patients with lymphoma, neuroblastoma, and several other types of nonepithelial malignancies. The radiobiologic mechanisms responsible for this high clinical radioresponsiveness are unclear, but must involve some sort of cytotoxic enhancement or sensitization to protracted courses of low-dose-rate radiation exposure. MATERIALS AND METHODS: A series of in vitro experiments was performed with malignant lymphoma cell lines exposed under various conditions to high-dose-rate external beam radiotherapy or low-dose-rate 90Y radiation. Data were collected on cell cycle effects, DNA fragmentation, and modulation of cytotoxicity by caffeine and treatment sequence alterations. RESULTS: The data showed that some malignant lymphoma lines are highly sensitive to low-dose-rate radiation and that a portion of the cytotoxicity appears to be mediated by the induction of radiation-associated apoptosis (programmed cell death). Cell cycle effects of low-dose-rate radiation (such as G2M block) appear to be relatively minor in this experimental system. Agents that modulate apoptosis (such as the calcium-releasing agent caffeine) significantly enhance cell kill and DNA fragmentation after 90Y treatment. CONCLUSIONS: These results suggest that radiation-associated apoptosis may be important in the radiobiology of targeted radiopharmaceutical therapy.
