Supercritical Foaming and Impregnation of Polycaprolactone and Polycaprolactone-Hydroxyapatite Composites with Carvacrol

Alina Satpayeva,Irena Zizovic,María José Galotto,Marcin Tyrka,Adrián Rojas,Ewelina Ksepko

doi:10.3390/pr10030482

Abstract

Polycaprolactone (PCL) and polycaprolactone-hydroxyapatite (PCL-HA) scaffolds were produced by foaming in supercritical carbon dioxide (scCO2) at 20 MPa, as well as in one-step foaming and impregnation process using carvacrol as an antibacterial agent with proven activity against Gram-positive and Gram-negative bacteria. The experimental design was developed to study the influence of temperature (40 °C and 50 °C), HA content (10 and 20 wt.%), and depressurization rate (one and two-step decompression) on the foams’ morphology, porosity, pore size distribution, and carvacrol impregnation yield. The characterization of the foams was carried out using scanning electron microscopy (SEM, SEM-FIB), Gay-Lussac density bottle measurements, and Fourier–transform infrared (FTIR) analyses. The obtained results demonstrate that processing PCL and PCL-HA scaffolds by means of scCO2 foaming enables preparing foams with porosity in the range of 65.55–74.39% and 61.98–67.13%, at 40 °C and 50 °C, respectively. The presence of carvacrol led to a lower porosity. At 40 °C and one-step decompression at a slow rate, the porosity of impregnated scaffolds was higher than at 50 °C and two- step fast decompression. However, a narrower pore size distribution was obtained at the last processing conditions. PCL scaffolds with HA resulted in higher carvacrol impregnation yields than neat PCL foams. The highest carvacrol loading (10.57%) was observed in the scaffold with 10 wt.% HA obtained at 50 °C.

Highlights

Introduction iationsBone fractures are a global public health issue
CO2 saturation pressure was fixed at 20 MPa based on previously published results [45]
The mechanical properties of scaffolds were screened by measuring the compression work aimed to investigate theB)

Summary

Introduction

Bone fractures are a global public health issue. In the last three decades, the incidence, prevalence, and years lived with disability increased 33, 70, and 65.3%, respectively, being women and older people the groups with a higher risk of fractures [1]. Actual clinical treatments for bone repair and regeneration, autologous and allogeneic transplantations using autografts and allografts, have significant shortcoming, limitations, and complications [2,3]. Autografts possess the essential components to achieve osteoinduction and osteoconduction, but the process involves harvesting bone from the patient’s iliac crest, which leads to a second operation at the site of tissue harvest. Autologous bone transplants are very expensive procedures with surgical risks such as bleeding, inflammation and infection, and may result in significant donor site injury, morbidity, deformity, scarring, and chronic pain.

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Conclusion