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.
Highlights
Appropriate selection of implant biomaterials is a key factor for the long-term success of implants.Implant biomaterials should be selected to reduce the negative biological response, while maintaining adequate function
The addition of methanol accelerated the decay of O2 (1 ∆g ) (Figure 5c), which corresponds with the literature data (τ∆ ~10 μs for methanol) [52], in comparison with τ∆ ~170 μs for chloroform. These results clearly show that polycyclic aromatic hydrocarbons (PAH) were released into the solvents, where they can sensitize the production of O2 (1 ∆g )
High temperature (500 ◦ C) calcination of silicalite-1 films liberated its microporous structure, which is potentially prospective in its applicability as an anticorrosive coating of implant metallic material
Summary
Appropriate selection of implant biomaterials is a key factor for the long-term success of implants. The PAHs may act as an O2 (1 ∆g ) sensitizer activated by irradiation [31,32], but they could be cytotoxic or genotoxic The last both properties would make calcined-SF inapplicable as a prosthetic material. PAH molecules undergo metabolic activation, catalyzed by cytochrome P450 enzymes or by aldo-reductases or keto-reductases, forming reactive metabolites (e.g., dihydrodiol epoxides or o-quinones, respectively) [34,35]. These metabolites can interact directly with cell proteins and DNA. We focused our attention on identifying PAH species in calcined-SF and on estimating their concentration and distribution between the outer surface and microporous structure of the samples
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