Copper-doped Ordered Mesoporous Bioactive Glass: A Promising Multifunctional Platform for Bone Tissue Engineering †.

Francesco Baino

doi:10.3390/bioengineering7020045

Abstract

The design and development of biomaterials with multifunctional properties is highly attractive in the context of bone tissue engineering due to the potential of providing multiple therapies and, thus, better treatment of diseases. In order to tackle this challenge, copper-doped silicate mesoporous bioactive glasses (MBGs) were synthesized via a sol-gel route coupled with an evaporation-induced self-assembly process by using a non-ionic block co-polymer as a structure directing agent. The structure and textural properties of calcined materials were investigated by X-ray powder diffraction, scanning-transmission electron microscopy and nitrogen adsorption-desorption measurements. In vitro bioactivity was assessed by immersion tests in simulated body fluid (SBF). Preliminary antibacterial tests using Staphylococcus aureus were also carried out. Copper-doped glasses revealed an ordered arrangement of mesopores (diameter around 5 nm) and exhibited apatite-forming ability in SBF along with promising antibacterial properties. These results suggest the potential suitability of copper-doped MBG powder for use as a multifunctional biomaterial to promote bone regeneration (bioactivity) and prevent/combat microbial infection at the implantation site, thereby promoting tissue healing.

Highlights

Over the last years, there has been an increasing interest in investigating the biological effects that can be elicited by ionic dissolution products released by implanted biomaterials
4.0 g of Pluronic P123 were dissolved in 60.0 g of ethanol with 1.0 g of 0.5 M HCl used as a catalyst under constant stirring at room temperature; once Pluronic P123 was completely dissolved, TEOS and salts were slowly added over 3 h following this order: 6.7 g of TEOS, 1.8 or 1.425 g of Ca(NO3)2·4H2O, and 0.054 or 0.27 g of CuCl2
Aged gels were removed from the dishes and calcined in air at 650 ◦C for 5 h; the selection of calcination temperature was performed according to the results from thermogravimetric analysis (TGA) on the gels

Summary

Introduction

There has been an increasing interest in investigating the biological effects that can be elicited by ionic dissolution products released by implanted biomaterials. Copper ions exhibit good antibacterial activity against both Gram-positive and Gram-negative bacteria [8] and, very interestingly, can stimulate the formation of collagen by bone cells, thereby contributing to osteogenesis and inhibiting osteoporosis [9]. All these attractive features make copper a valuable dopant to be incorporated in bioactive ceramics and glasses for making multifunctional biomaterials, which combine osteoconduction/osteoinduction with new therapeutic extra-functionalities. Doping of sol-gel silicate glass compositions with copper has been recently proposed as an interesting approach for obtaining multifunctional biomaterials combining tissue regenerative and antibacterial capabilities [18,19,20,21]. This work reports the synthesis of copper-doped glasses via a modified sol-gel method incorporating supramolecular chemistry, which allows mesoporous bioactive materials to be obtained

Preparation

Characterization

Results and Discussion