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Controlled Drug Delivery in Photodynamic Therapy and Fluorescence-Based Diagnosis of Cancer
Published in Mary-Ann Mycek, Brian W. Pogue, Handbook of Biomedical Fluorescence, 2003
Jori and coworkers were the first to study the impact of liposomes on the biodistribution of Hp following IP administration [99]. The tumor uptake of Hp encapsulated in unilamellar liposomes of dipalmitoylphosphatidylcholine (DPPC) in MS-2 fibrosarcoma bearing mice was found to be slower as compared with the free drug. However, the final tumor concentration of liposomal-formulated Hp was approximately twice as high, while uptake in normal skin was lower than with the free Hp. Similar experimental conditions were used with another photosensitizing agent, Zn(II)phthalocyanine (ZnPC), by the same group [100]. Phthalocyanine and naphthalocyanine (Nc) dyes are highly hydrophobic and belong formally to the family of tetraazaporphyrins, with four benzenoid or naphthaloid rings attached to the tetrapyrrolic skeleton, respectively. In this study, maximal tumor concentrations of 0.6 μg/g tissue at 24 hr after IP application were reported, while for the same drug IV administration resulted in 0.3 μg/g tumor tissue using approximately fourfold lower drug doses [101]. For IP administration, the maximal tumor/muscle ratio was found to be 7.5 at 24 hr postinjection, which was twice as high as for IV injection. For both administration routes, never more than 0.1 μg/g tissue was observed in the skin between 1 and 168 hr postadministration. The highest T/N ratio with this photosensitizer was observed when ZnPc was delivered in a liposomal formulation consisting of a mixture of palmitoyloleoylphosphatylcholine (POPC) and dioleoylphosphatylcholine (9:1) instead of DPPC liposomes [102]. Approximately 10 times more of the photosensitizer was found in the tumor than in the normal tissue 48 hr after IV administration in Meth-A sarcoma-bearing mice.
Synthesis of low cost organometallic-type catalysts for their application in microbial fuel cell technology
Published in Environmental Technology, 2019
A. Zerrouki, M. J. Salar-García, V. M. Ortiz-Martínez, S. Guendouz, H. Ilikti, A. P. de los Ríos, F. J. Hernández-Fernández, M. Kameche
Despite the advantages of this promising technology, there are some drawbacks that need to be overcome in order to improve its large-scale application. The main problem is the use of expensive catalysts such as noble metals that are used to obtain high performances. Many advances have been made in this field and, recently, novel non-platinum catalysts have been studied as low cost alternatives [4]. Among the most promising materials are manganese oxides and iron and cobalt chelates [8]. Lu et al. [9] studied different manganese dioxides (α-MnO2, β-MnO2 and γ-MnO2) combined with carbon nanotubes in single-chamber air-cathode MFCs. The best result was achieved with β-dioxide, in line with the data reported by Zhang et al. [10], who used graphite instead of carbon nanotubes. These catalysts were ranked as Pt > β > γ > α, β-MnO2 achieving 64% out of the performance displayed by a carbon/Pt electrode. As mentioned above, other alternatives are cobalt-carbon composites such as cobalt chelates and cobalt oxide-CoPc composites supported on carbon black. Several authors have studied the performance of MFCs using cobalt-naphthalocyanine and cobalte-porphyrin onto carbon black as supporting material. The results achieved with naphthalocyanine complex were similar to those obtained using carbon/Pt [11,12]. Iron has also been used as chelate and oxide on different carbonaceous supports in MFCs. For instance, Birry et al. [13] used clorine-Fe(III) tetramethoxyphenylporphyrin (ClFeTMPP) and Fe(II) phthalocyanine (FePc) spread onto carbon black pyrolyzed electrodes. FePc-based cathodes reached a performance in the range of 550–590 mW.m−2 at very low iron loading (0.01–0.016 mg.cm−2), which is comparable to the power generated with carbon/Pt. Other metals, such as silver combined with hybrid tungsten carbide, offered similar power performances to those achieved with Pt/C-based cathodes in double chamber MFCs [14]. On the other hand, Lefebvre et al. [15] tested several recycled scrap metals as cathode materials, showing the increasing trend W/Co > Cu/Ni > Iconel 718 > Carpenter alloy. However, due to its stability and low cost, Iconel 718 (nickel-chrome-molybdenum alloy) could be considered as a preferable option. All these works demonstrate the recent scientific interest in the optimization of this technology.