Correlation of the Photocatalytic Activities of Cu, Ce and/or Pt-Modified Titania Particles with their Bulk and Surface Structures Studied by Reversed Double-Beam Photoacoustic Spectroscopy

Modified titania photocatalyst powder samples were prepared using the sol-gel method for copper (Cu) and cerium (Ce) doping and impregnation for platinum (Pt) loading. Their bulk crystalline structures were investigated using X-ray diffractometry (XRD) with the Rietveld analysis. The surface/bulk structure, surface properties, and morphologies were observed using reversed double-beam photoacoustic spectroscopy (RDB-PAS), nitrogen adsorption, and scanning electron microscopy, respectively. The results from the XRD revealed that all samples were mainly anatase (ca. 80% or higher) with small amounts of rutile and non-crystalline components. The specific surface areas of all samples were in the range of 115–155 m2 g−1. Ce and Cu species were mainly distributed, while Pt was potentially loaded as a partially oxidized form on the titania surface. The results from the RDB-PAS indicated the changing of the energy-resolved distribution of electron traps (ERDT) from the original titania surface upon doping of the metals (Cu, Ce, and Pt), which altered their catalytic activities. The metals photocatalytic activities with UV irradiation were measured in two representative reactions; (a) CO2 evolution from acetic acid under the aerobic condition and (b) H2 evolution from deaerated aqueous methanol. In reaction (a), the Cu and/or Ce modification gave almost the same or slightly lower activity compared to the non-modified titania samples, while platinum loading yielded ca. 5–6 times higher activity. For reaction (b), the photocatalytic tests were divided into two sets; without (b1) and with (b2) Pt deposition during the reaction. Similar enhancements of activity from the Pt loading sample (and by Cu modification) were observed in reaction (b1) without in-situ platinum deposition, while the unmodified and Ce-doped samples were almost inactive. For the activities of reaction (b2) with in-situ platinum deposition, the unmodified samples showed the highest activity while the Cu-modified samples showed significantly lower activity.

Catalytic consequences of platinum deposition order on cobalt-based Fischer–Tropsch catalysts with low and high cobalt oxide dispersion

In this study, the effect of the presence of Pt in supported Co-based Fischer–Tropsch catalysts is investigated.

Platinum deposition in skin as a possible mechanism for peripheral sensory neuropathy (PSN) in patients (pts) with colorectal cancer (CRC) following oxaliplatin-based therapy.

685 Background: Oxaliplatin plus fluorouracil (FOLFOX) is a standard treatment for CRC pts. One of the most common and dose-limiting side effects of oxaliplatin is PSN. The mechanism of this phenomenon is poorly understood. Previous studies suggested that higher serum platinum levels were related to more severe neuropathy in testicular cancer pts. Methods: CRC pts who completed adjuvant FOLFOX at least 6 months prior to enrollment are eligible. Baseline demographic and treatment information were collected. EORTC CIPN20 (with EORTC QLQ-C30) questionnaire was used for self-reported PSN symptom assessment. Peripheral blood samples were collected for total/free platinum concentrations using high-performance liquid chromatography with tandem mass spectrometry (HPLC/MS-MS). Skin biopsies were obtained from the lower leg of consented pts. Imaging mass cytometry (IMC) was used to visualize platinum deposition (195Pt) and intra-epidermal nerve fiber (IENF) (PGP9.5-154Sm) in formalin-fixed paraffin embedded (FFPE) skin biopsy samples stained with a metal-conjugated antibody cocktail. Results: Nine patients were enrolled. Median age was 51.8 yr (range: 34.5-69.4 yr); male/ female: 5/4; mean cumulative dose of oxaliplatin was 800.7 ± 188.2 mg/m2; median time from last dose of oxaliplatin to enrollment was 48 months (range: 7.2-65.6 months). The mean sensory score from CIPN20 was 15.4 ± 4.3 (range: 10-25). Platinum was undetectable in plasma samples collected from all 9 patients. In skin samples, IMC showed significant platinum depositions and IENF. Conclusions: Severity of PSN was not related to cumulative dose of oxaliplatin or interval from last dose of oxaliplatin. Although platinum was undetectable in plasma in these patients, platinum was readily detectable in skin biopsies up to 65.6 months post completion of FOLFOX. This is the first demonstration of platinum deposition in skin post oxaliplatin treatment and it provides a possible mechanism for oxaliplatin-induced PSN.