Pukyong National University

Photothermal therapy (PTT) has been used as a non-invasive and effective anti-tumor treatment by localizing optical energy in the tissue. The aim of the current study was to investigate the efficacy and safety of PTT against tumor by applying multi-lens arrays (MLA) for having uniform micro-beam distributions and power modulation (MD) for sustaining constant treatment temperature in the tissue. A 1064 nm laser system delivered the equivalent energy (270 J) through two different manners (flat optical fiber; Flat and MLA) to a target under three different irradiation conditions: 1.5 W/cm2 for 180 s, 3 W/cm2 for 90 s and 3 W/cm2 for 60 s followed by 1.5 W/cm2 for 60 s (MD). In vivo tests demonstrated that MLA was able to expand a distribution of constant temperature (up to 40%) and the extent of thermal coagulation (up to two-fold) in the tumor than Flat. Irresp. of delivery method, MD maintained a constant temperature (around 60 °C) for 60 s, compared to fixed power, resulting in insignificant tumor recurrence ten days after treatment. MLA-assisted PTT with MD could enhance a therapeutic capacity against the tumor tissue by covering a wide treatment area with larger coagulative necrosis and less thermal injury.

Anthropogenic gadolinium (Gd_anth) has been reported in rivers as a result of magnetic resonance imaging. We collected seasonal water samples from the Suyeong River Basin, to investigate seasonal variations in dissolved rare earth elements (REEs) and Gd_anth in highly urbanized areas. The post-Archean Australian shale-normalized REE patterns indicate a significant influence of terrestrial source inputs during the summer. Although higher concentrations of dissolved REEs were measured in summer than in winter, the Gd_anth concentrations exhibited similar levels. During winter, the concentrations of Gd_anth showed conservative mixing trends downstream of the wastewater treatment plant (WWTP), whereas no clear trend was observed in summer. Moreover, the estimated daily discharge of Gd_anth accounts for approx. 11-22% of the number of MRI tests performed, when the WWTP treats only 6% of Busan area size. Our results suggests that the elevated Gd_anth level in the highly urbanized river basin is a major concern.

The discharge of azo-dye mols. in wastewater has raised significant environmental and health concerns. Therefore, the development of visible light-active photocatalysts to degrade the dye mols. in wastewater can be a promising solution In this study, Cu_xFeS_x derivatives were synthesized by solvo-hydrothermal method with different solvents (deionized water (Wt), ethanol-Wt (Et-Wt) and Et) to investigate their photocatalytic activity towards Direct Red 80 (DR-80) and safety in human cell lines. The physicochem. properties of the synthesized products, including crystallinity, surface morphol. and chem. properties were characterized. The results showed that Cu_xFeS_x-Wt and Cu_xFeS_x-Et-Wt produced flower-like morphol. interconnected with nanosheets, while Cu_xFeS_x-Et is produced a mixture of edged particles and nanosheets. Among them, CuxFeS_x-Et exhibited the highest photocatalytic efficiency of DR-80 at 98.76% in 195 min, compared to Cu_xFeS_x-Et-Wt (96.17% in 240 min) and Cu_xFeS_x-Wt (93.32% in 285 min). Cu_xFeS_x-Et also showed a high recyclability of 94.93%. The degradation of DR-80 dye followed the Langmuir adsorption model. Furthermore, the low cytotoxicity of Cu_xFeS_x nanocomposites to human intestinal epithelial cell line (Caco-2) and human macrophage-like cell line (differentiated THP-1) suggests that these materials are benign. This study provides new insights into the benign-by-design of Cu_xFeS_x as photocatalysts for the degradation of dye mols. in environmental remediation.