Sterile and Dual-Porous Aerogels Scaffolds Obtained through a Multistep Supercritical CO₂-Based Approach.

Víctor Santos-Rosales,Nilza Ribeiro,Inés Ardao,Ana Oliveira,Carlos García-González,Carmen Alvarez-Lorenzo

doi:10.3390/molecules24050871

Abstract

Aerogels from natural polymers are endowed with attractive textural and biological properties for biomedical applications due to their high open mesoporosity, low density, and reduced toxicity. Nevertheless, the lack of macroporosity in the aerogel structure and of a sterilization method suitable for these materials restrict their use for regenerative medicine purposes and prompt the research on getting ready-to-implant dual (macro + meso)porous aerogels. In this work, zein, a family of proteins present in materials for tissue engineering, was evaluated as a sacrificial porogen to obtain macroporous starch aerogels. This approach was particularly advantageous since it could be integrated in the conventional aerogel processing method without extra leaching steps. Physicochemical, morphological, and mechanical characterization were performed to study the effect of porogen zein at various proportions (0:1, 1:2, and 1:1 zein:starch weight ratio) on the properties of the obtained starch-based aerogels. From a forward-looking perspective for its clinical application, a supercritical CO2 sterilization treatment was implemented for these aerogels. The sterilization efficacy and the influence of the treatment on the aerogel final properties were evaluated mainly in terms of absence of microbial growth, cytocompatibility, as well as physicochemical, structural, and mechanical modifications.

Highlights

IntroductionThe increase in life expectancy, the popularization of physical activity in society, and the high obesity ratios have strongly increased the incidence of bone diseases and traumatic fractures.The scarcity of donor grafts and the associated clinical complications (autoimmune response) even with autologous procedures (risk of surgeries sequalae and donor morbility), have prompted the development of innovative synthetic grafts (scaffolds) [1]
The increase in life expectancy, the popularization of physical activity in society, and the high obesity ratios have strongly increased the incidence of bone diseases and traumatic fractures.The scarcity of donor grafts and the associated clinical complications even with autologous procedures, have prompted the development of innovative synthetic grafts [1]
Macroporosity of 1–2 μm in starch aerogels was induced by the addition of zein, a biocompatible porogen, without involving an extra leaching step, like in other conventional practices

Summary

Introduction

The increase in life expectancy, the popularization of physical activity in society, and the high obesity ratios have strongly increased the incidence of bone diseases and traumatic fractures.The scarcity of donor grafts and the associated clinical complications (autoimmune response) even with autologous procedures (risk of surgeries sequalae and donor morbility), have prompted the development of innovative synthetic grafts (scaffolds) [1]. Aerogels are lightweight materials with outstanding textural properties that allow the manufacturing of multishape structures from different inorganic and organic sources [5,6] Since their invention back in the 1930s [7], many different fields (e.g., electrical and chemical applications, aerospace, and building industries) [8,9,10,11] have taken advantage of their low acoustic and thermal conductivity, extremely low density, and high open porosity. Current research on bio-based aerogels has been mainly focused on drug delivery systems [6] with only few examples in the spotlight of the regenerative medicine [4,14,15,16] For the latter case, a fast ingress of body fluids in the aerogel scaffold will take place by capillarity just after implantation due their initial dry state accelerating integration of the material. There are several FDA-compliant starch varieties that have demonstrated the capacity of promotion of cell adhesion and growth and of the phenotypic expression of osteoblastic markers [18]

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Results

Conclusion