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- Karlsson, P G, et al.
(författare)
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Interfacial properties of the nanostructured dye-sensitized solid heterojunction TiO2/RuL2(NCS)(2)/CuI
- 2004
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 120:23, s. 11224-11232
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Tidskriftsartikel (refereegranskat)abstract
- The interfaces of the nanostructured dye-sensitized solid heterojunction TiO2/Ru-dye/CuI have been studied using photoelectron spectroscopy of core and valence levels, x-ray absorption spectroscopy and atomic force microscopy. A nanostructured anatase TiO2 film sensitized with RuL2(NCS)(2) [cis-bis(4,4'-dicarboxy-2,2'-bipyridine)-bis(isothio-cyanato)-ruthenium(II)] was prepared in a controlled way using a novel combined in-situ and ex-situ (Ar atmosphere) method. Onto this film CuI was deposited in-situ. The formation of the dye-CuI interface and the changes brought upon the dye-TiO2 interface could be monitored in a stepwise fashion. A direct interaction between the dye NCS groups and the CuI is evident in the core level photoelectron spectra. Concerning the energy matching of the valence electronic levels, the photoelectron spectra indicate that the dye HOMO overlaps in energy with the Cu 3d-I 5p hydrid states. The CuI grow in the form of particles, which at the initial stages displace the dye molecules causing dye-TiO2 bond breaking. Consequently, the very efficient charge injection channel provided by the dye-TiO2 carboxylic bonding is directly affected for a substantial part of the dye molecules. This may be of importance for the functional properties of such a heterojunction. (C) 2004 American Institute of Physics.
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- Lukes, Daniel J, et al.
(författare)
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Early onset of rejection in concordant hamster xeno hearts display signs of necrosis, but not apoptosis, correlating to the phosphocreatine concentration.
- 2003
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Ingår i: Transplant immunology. - 0966-3274. ; 12:1, s. 29-40
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The importance of apoptosis contra necrosis for ischemia/reperfusion (RP) and acute rejection in concordant rodent xenotransplantation is largely unknown. We explored this question by comparing rodent allo and concordant xenotransplants with different morphological methods to detect apoptosis and biochemical data on the levels of high-energy phosphates obtained with in vitro 31Phosphorous Magnetic Resonance Spectroscopy (31P MRS). More specifically, we applied a hitherto unused method in transplantation research, apoptosis specific biotin labeled oligonucleotides designed with a 10 base pair stem region and a 20 nucleotides large loop that form a hairpin like shape. The results obtained with this method were compared to results obtained with the more widely used in situ 3'-end labeling of DNA (TUNEL) assay and extraction and gel electrophoresis of labeled DNA (DNA laddering). METHODS: Cervical heart transplantations were performed between inbred Lewis (L) (RT1l) to L, L to DA (RT1a) rats, hamster (H) to H and H to L (X) (n=5 for all groups except for X, n=9). All hearts were subjected to 30 min of cold ischemia (+4 degrees C) and 6 h of RP before explantation. In vitro 31P MRS was used to determine the phosphocreatine (PCr), beta-adenosine triphosphate (beta-ATP) concentrations and the PCr/beta-ATP ratio of the transplants. We correlated the biochemical data to haematoxylin and eosin (H & E) stained tissue slides scored for rejection, infiltration of antibodies and complement depositions, DNA extraction and gel electrophoresis of labeled DNA (DNA laddering), in situ 3'-end labeling of DNA (TUNEL) and the apoptosis specific hairpin probe assays scoring. RESULTS: The rejection score of the xeno grafts differed significantly compared to their syngeneic hamster to hamster controls (2.40 +/- 0.25 vs. 1.20 +/- 0.20; P=0.005) and they had a significantly higher TUNEL score, 228 +/- 15 vs. 2.44 +/- 0.32 (P=0.009), that correlated to changes in PCr concentration (P<0.001) and to the PCr/beta-ATP ratio (P=0.01). The uptake was mainly (90-95%) located to 1-2 microm large extra cellular 'granule'. A picture resembling early necrosis was seen on the H & E stainings and reflected in the Billingham rejection score above. CONCLUSIONS: After 6 h of RP the onset of acute rejection in the concordant hamster xeno hearts displayed features of early, possibly mitochondrial, necrosis, but not apoptosis, which correlated to changes in the PCr concentration and the PCr/beta-ATP ratio. The mechanism for the early rejection observed is unclear and might be caused by other factors in the sera apart from cellular components, antibodies and complement factors. Identification of the underlying mechanisms could enable us to design rational therapies that prevent activation of the recipient's innate immune response.
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