Abstract
Gamma irradiation is able to affect various structural and biological properties of biomaterials In this study, a composite of Hap/PLGA-PEG and their ingredients were submitted to gamma irradiation doses of 25 and 50 KGy. Various properties such as molecular weight (GPC), thermal behavior (DSC), wettability (contact angle), cell viability (MTT assay), and alkaline phosphatase activity were studied for the composites and each of their ingredients. The results showed a decrease in molecular weight of copolymer with no change in the glass transition and melting temperatures after gamma irradiation. In general gamma irradiation can increase the activation energy ΔH of the composites and their ingredients. While gamma irradiation had no effect on the wettability of copolymer samples, there was a significant decrease in contact angle of hydroxyapatite and composites with increase in gamma irradiation dose. This study showed an increase in biocompatibility of hydroxyapatite with gamma irradiation with no significant effect on cell viability in copolymer and composite samples. In spite of the fact that no change occurred in alkaline phosphatase activity of composite samples, results indicated a decrease in alkaline phosphatase activity in irradiated hydroxyapatites. These effects on the properties of PLGA-PEG-hydroxyapatite can enhance the composite application as a biomaterial.
Highlights
Biodegradable polymers and bioactive ceramics are widely used for bone tissue engineering
Chain scissoring and a decrease in molecular weight are the main impact of gamma irradiation on copolymers in a dose dependent manner
Our results showed that there was a significant decrease in molecular weight of polymer with gamma irradiation which was in agreement with the results of the previous studies [15,16,17,18,19]
Summary
Biodegradable polymers and bioactive ceramics are widely used for bone tissue engineering. They combine to form a variety of composites which are able to achieve the strength of inorganic phase with the formability of organic phase at the same time [1]. Structural and biological properties of materials can be affected by gamma irradiation as well [5, 6]. In a dose dependent manner, gamma irradiation is able to reduce molecular weights of polymers due to radical production [7]. Biocompatibility and bioactivity of biomaterials can be affected, and it is shown that the bioconductivity and absorption of these materials are dependent upon irradiation dose [10]
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