The Photodynamic Properties and the Genotoxicity of Heat-Treated Silicalite-1 Films

Abstract

We investigated the use of a supported silicalite-1 film (SF) as a promising coating for metallic materials used in the fabrication of prostheses. The role of carbonaceous residua present on high-temperature calcined-SF in generating singlet oxygen for future use as a sterilization method has also been addressed, and the potential genotoxicity of these residua in osteoblast-like cells has been investigated. Calcination of as-synthesized SF induced the appearance of a rather complicated mixture of aliphatic and aromatic species on its outer surface. A series of variously volatile polycyclic aromatic hydrocarbons (PAH), including naphthalene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene, were identified in micromole concentrations. Irradiation of these PAHs on calcined-SF immersed in air-saturated chloroform led to the formation of very low concentrations of singlet oxygen. However, an increased level of DNA damage was observed on calcined-SF by immunofluorescence staining of phosphorylated histone H2AX analyzed by flow cytometry.

Heat treatment dependent cytotoxicity of silicalite-1 films deposited on Ti-6Al-4V alloy evaluated by bone-derived cells

“…These results are in agreement with our previous study, which evaluated the photodynamic and genotoxic properties of SFs deposited on stainless steel 33 . In full agreement with our results, this paper showed increased induction of double-strand breaks in U-2 OS cells grown on SF-500, but not on SF-RT (labelled as SF-AS).…”

“…However, some hydrocarbon residua remained in SF-500. Line 5 at 1712 cm −1 , assigned to cyclohexanone 33 , appeared in the spectrum of this sample. The intensity of overtone band 6 of SF-500 at ~1642 cm −1 was slightly increased due to an overlap with another band of aromatic species.…”

“…The intensity of overtone band 6 of SF-500 at ~1642 cm −1 was slightly increased due to an overlap with another band of aromatic species. The shoulder 7 at ~1617 cm −1 of SF-500 belongs to physisorbed water 33 .…”

“…This study also revealed the presence of residual polycyclic aromatic hydrocarbon species (PAHs) created during the heat treatment of SF-500. A series of various PAH molecules, including naphthalene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene, were identified and quantified on the SF-500 surface 33 . The cytotoxicity and the genotoxicity of these molecules, including the genotoxicity mechanism, have been rigorously discussed in our previous study and also in studies of other authors 33,[78][79][80][81] .…”

“…As-synthesized coatings have improved the adhesion and proliferation of human osteosarcoma cell lines Saos-2 and MG-63. Interestingly, calcined films (at 500 °C) displayed lower cell numbers and an increased DNA damage response of osteosarcoma cell lines 30,33 . However, a similar increase in DNA damage was also observed in cells grown on the reference stainless steel without SFs.…”