Effect of Gamma Irradiation on Structural and Biological Properties of a PLGA-PEG-Hydroxyapatite Composite

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.

Effect of hydroxyapatite nanoparticles addition on structure properties of poly(l‐lactide‐co‐glycolide) After gamma sterilization

“…This research confirmed significant decrease of polymer molecular weight due to the chain scission mechanism. They showed that gamma irradiation caused insignificant decrease of T g and T m and a slight decrease of the contact angle in this copolymer . However, there is no information about the effect of nanoparticle incorporation on the PLGA structure and its mechanical properties after sterilization by gamma irradiation.…”

“…Radiation may also be used for chemical modification of the polymer samples' surface to improve cell adhesion . Unfortunately, in some polymers, such as PLGA, sterilization by gamma radiation significantly changes the properties by reducing the molecular weight . The mechanism of degradation does not depend on the type of radiation used.…”

“…To date, the impact of gamma radiation and other methods of sterilization on the structure and properties of PLGA has been extensively studied . For example, Shahabi et al focused on the impact of different doses of gamma radiation on PLGA‐PEG/hydroxyapatite composite. This research confirmed significant decrease of polymer molecular weight due to the chain scission mechanism.…”

Desenvolvimento da metodologia de síntese e purificação dos dímeros L-lactídeo e glicolídeo para produção do poli (ácido lático-co-ácido glicólico) para utilização na produção de fontes radioativas

“…A esterilização por radiação gama é um método que tem-se mostrado bastante eficiente para tratar materiais médicos ou farmacêuticos [263][264][265]268,270]. Devido ao aumento da utilização de dispositivos médicos descartáveis nos últimos anos, houve um aumento considerável na utilização desse tipo de procedimento.…”

“…Alguns trabalhos reportam a influência da radiação nas propriedades do PLGA usando altas doses, porém, estudos mostrando a influência de baixas doses usadas para esterilização (~ 25 kGy) são escassos [264,270,272,274]. Embora a dose de 25 kGy seja considerada padrão para esterilização de dispositivos médicos, doses menores podem ser utilizadas, se a validação do processo for possível [265,271].…”