Generation of oxyradicals (O2. and H2O2), mitochondrial activity and induction of apoptosis of PBMC of Cyprinus carpio carpio treated in vivo with halomethanes and with recombinant HSP60 kDa and with LPS of Klebsiella pneumoniae

Halomethanes (HM) can be immunotoxic in mammals; however, in the fish immune system HM effects are unknown. In the current study, we evaluated the mitochondrial activity (MA) by MTT, induction of apoptosis by SubG0 technique and quantified serum ROS concentration (O2. and H2O2) and ROS production in PBMC of Cyprinus carpio carpio treated i.p. with CH2Cl2, CHCl3 and BrCHCl2 (0.004-40.0 mg/kg) for 96 h. Positive controls were recombinant heat shock protein of 60 kDa (rHSP60 kDa) of Klebsiella pneumoniae and its LPS. In addition, for in vitro PBMC cultures, two culture media and two sources of sera were tested. Both positive controls increased the MA more than 4-fold as well as the production of O2. (26-fold) and H2O2 (5-fold) compared to their controls. HM induced different effects on MA, ROS production and an induction of apoptosis, depending on the chlorination patterns and the dose; however, a systemic damage prevails. To fish treated with CH2Cl2, the apoptosis was related with serum ROS concentration and with MA. In contrast, in fish dosed with CHCl3 relationships were not found, deducing a systemic damage. However, in fish treated with BrCHCl2, serum O2. concentration and in vitro ROS generation performed by PBMC were involved in the induction of apoptosis of these cells but not with MA suggesting also immunotoxic effects. The current study demonstrated that HMs are immunomodulators increasing an acute inflammatory response and that rHSP60kDA of K. pneumoniae and its LPS are appropriate antigens to assess the immune response of C. c. carpio.

In situ X-ray absorption spectroscopic studies of TiO2 photocatalytic active sites for degradation of trace CHCl3 in drinking water

Toxic disinfection byproducts such as trihalomethanes (e.g. CHCl₃) are often found after chlorination of drinking water. It has been found that photocatalytic degradation of trace CHCl₃ in drinking water generally lacks an expected relationship with the crystalline phase, band-gap energy or the particle sizes of the TiO₂-based photocatalysts used such as nano TiO₂ on SBA-15 (Santa Barbara amorphous-15), TiO₂ clusters (TiO₂-SiO₂) and atomic dispersed Ti [Ti-MCM-41 (Mobil Composition of Matter)]. To engineer capable TiO₂ photocatalysts, a better understanding of their photoactive sites is of great importance and interest. Using in situ X-ray absorption near-edge structure (XANES) spectroscopy, the A₁ (4969 eV), A₂ (4971 eV) and A₃ (4972 eV) sites in TiO₂ can be distinguished as four-, five- and six- coordinated Ti species, respectively. Notably, the A₂ Ti sites that are the main photocatalytic species of TiO₂ are shown to be accountable for about 95% of the photocatalytic degradation of trace CHCl₃ in drinking water (7.2 p.p.m. CHCl₃ gTiO₂^-1 h^-1). This work reveals that the A₂ Ti species of a TiO₂-based photocatalyst are mainly responsible for the photocatalytic reactivity, especially in photocatalytic degradation of CHCl₃ in drinking water.

Chain Reduction of CHCl3 Photocatalyzed by SPEEK/PVA Films Swollen in Air-Saturated HCO2Na Solutions

Thin cross-linked films containing sulfonated poly(ether etherketone), SPEEK, and poly(vinyl alcohol), PVA, served as efficient photocatalysts for the reduction of CHCl3 when swollen in air-saturated solutions of formate buffers were photolyzed with 350 nm photons. The phototransformation generated CH2Cl2, CO2 and Cl- as products. The utilization of the continuous extraction method coupled with in situ potentiometry enabled kinetic determinations of the reaction progress. Quantum yields of halide ion formation, ϕ(Cl-), larger than 1 were obtained in the presence of air. These findings, together with the occurrence of a post-irradiation Cl- formation, indicated that the photoreduction took place via a chain process. Reductions photoinitiated by swollen films exhibited ϕ(Cl-) values between 3 and 20 times higher than the reactions induced in solutions containing the two polymers. Also, the dependencies of ϕ(Cl-) on CHCl3 or HCO2- concentration diverged significantly from the trends observed using solutions. Most findings are consistent with the occurrence of a reaction mechanism involving SPEEK radicals, •CO2- and •CHCl2 as chain carriers.