Journal Title: زمستان 1400
Article title: Investigation of electrical properties of graphene nanosheets used in biodegradable composite nanostructures based on polylactic acid-polycaprolactone reinforced with Hydroxyapatite nanoparticles for use in bone tissue surgery

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Article abstract:
Introduction & Objective: Metal implants are used when bone tissue is damaged. Implants available for use in bone tissue that are implanted in the body due to trauma injuries and bone injuries require a second surgery to remove the implant from the body after repairing the damaged tissue. Therefore, the purpose of this study is to design a biodegradable implant suitable for bone tissue that, in addition to having biodegradability, has sufficient mechanical strength to be used in hard tissue. In this study, mechanical properties, surface morphology, electrical properties, surface wettability and bioactivity were investigated. Finally, a scaffold was found that was suitable for use in bone tissue surgery. Materials & Methods: In this study, nano composites were fabricated by solution casting. Tensile test was taken from the samples to evaluate the mechanical properties. Field emission scanning electron microscopy was used to examine the surface morphology of the nanocomposites and to evaluate the bioactivity before and after immersion in SBF solution. The electrical conductivity test was performed by four probes to check the electrical conductivity of the samples and the surface wettability was measured by measuring the contact angle of water. Data were obtained as mean standard deviation (MEAN ± SD) and for statistical analysis SPSS software (version 16) was used and one-way analysis of variance (ANOVA) was used, the level of significant differences with (P < 0.005) was calculated. Results: It was found that the nanocomposite contained 1% graphene with a Young's modulus of 1540.5 ± 169.426MPa and the pure sample had a Young's modulus of 1194.81±215.342MPa. The rate of elongation at break of the nanostructure contained 1% graphene was 5.1±0.816%. This value was 3.8±0.944% for the pure sample. The improvement in elongation at break is due to the presence of polycaprolactone in the polymer matrix. Also, the electrical conductivity increased from 0.00158±0.0008 S / M for the graphene-free sample to 0.0092±0.0021 S / M for the sample containing 1% Graphene, which indicates that the graphene plates have opened well in the polymer field and have created electrical conduction channels. Also, the wettability of the nanostructured surface containing 1% graphene was higher than that of the polymer matrix and increased from 88° to 84°. The growth of apatite crystals on the surface of nanocomposites indicates the bioactivity of nanocomposites. Conclusions: Findings of this study showed that the presence of graphene nanoparticles in addition to improving the mechanical properties of the matrix has improved the electrical conductivity and also improved the hydrophilicity of the surface. The findings of this study showed that the optimal nanocomposite is suitable for use in spongy bone tissue surgery. Due to the Young's modulus of optimal nanostructure, this nanocomposite is suitable for use in spongy bone tissue surgery and can be a suitable alternative as biodegradable screws and plates and scaffolds for bone tissue engineering.
Article KeyWords:
Biodegradable Nanocomposites, Graphene, Hydroxyapatite, Electrical Conductivity, Biodegradable Screw
Article Authors:

	فرناز دهقانی فیروزآبادی	First Author
	دکتر احمد رمضانی سعادت آبادی	Other Author	ramazani@sharif.edu
	دکتر آزاده آصف نژاد	Other Author
	دکتر علی عبداللهی	Other Author