The effect of ozone gas sterilization on the properties and cell compatibility of electrospun polycaprolactone scaffolds

Abstract

The growing area of tissue engineering has the potential to alleviate the shortage of tissues and organs for transplantation, and electrospun biomaterial scaffolds are extremely promising devices for translating engineered tissues into a clinical setting. However, to be utilized in this capacity, these medical devices need to be sterile. Traditional methods of sterilization are not always suitable for biomaterials, especially as many commonly used biomedical polymers are sensitive to chemical-, thermal- or radiation-induced damage. Therefore, the objective of this study was to evaluate the suitability of ozone gas for sterilizing electrospun scaffolds of polycaprolactone (PCL), a polymer widely utilized in tissue engineering and regenerative medicine applications, by evaluating if scaffolds composed of either nanofibres or microfibres were differently affected by the sterilization method. The sterility, morphology, mechanical properties, physicochemical properties, and response of cells to nanofibrous and microfibrous PCL scaffolds were assessed after ozone gas sterilization. The sterilization process successfully sterilized the scaffolds and preserved most of their initial attributes, except for mechanical properties. However, although the scaffolds became weaker after sterilization, they were still robust enough to use as tissue engineering scaffolds and this treatment increased the proliferation of L929 fibroblasts while maintaining cell viability, suggesting that ozone gas treatment may be a suitable technique for the sterilization of polymer scaffolds which are significantly damaged by other methods.

Keywords:

• Sterilization
• PCL
• electrospinning
• ozone
• tissue engineering
• scaffolds

Acknowledgments

We gratefully acknowledge Mrs Tais Cecchi (Brasil Ozônio) for the use of the ozone sterilizer, Mr Douglas Santos (IPT) for helping with the thermoanalytical assays, Mr Fernando Soares (IPT) for advice on mechanical testing, Mr Renato Gavioli and Mr Denivaldo Mota (IPT) for their help and advice with electron microscopy, and Mr Marcelo Medina (IPT) for advice on the live/dead assays. Also, we would like to thank Prof. Silvya Stuchi for the use of the plate reader and CEFAP/ICB/USP for the use of the fluorescent microscope.