Marcela Arango-Ospina <marcela.arango@fau.de>

I was born in Pereira, Colombia; I have a bachelor degree in Engineering Physics and a Master in Biomedical Engineering from the National University of Colombia. Additionally, I did a Master in Advanced materials and processes at the University of Erlangen Nuremberg. Currently, I am in my first year of doctoral studies working in the field of bioactive glasses for bone tissue regeneration.

Design and development of Ag-doped mesoporous bioactive glass based scaffolds derived from natural marine sponges
*Marcela Arango-Ospina, Francesca Ciraldo & Aldo R. Boccaccini
Institute of Biomaterials, Department of Material Science and Engineering, University of Erlangen-Nuremberg, Cauerstr.6, 91058 Erlangen, Germany 

Currently, countries worldwide are experiencing an exceedingly high demand for functional bone grafts. Annually in the United States, more than half a million patients experience bone defect repair. In 2020 this number is expected to double due to factors such as increased life expectancy and improvement of life conditions1.

Considerable limitations and complications of current clinical treatments for bone repair and regeneration are reported, autologous and allogeneic transplantations using autografts and allografts are among them1–3.  Therefore bone defect repair using the bone tissue engineering approach is of great interest since it offers the possibility to develop biological substitutes that restore, maintain and improve the tissue function4.

In bone reconstruction surgeries, bacterial infection is the main complication. Conventional treatments include systemic antibiotic administration, nevertheless this approach is not always efficient, and the patients may suffer from extra surgeries. An alternative approach to solve the problem is to introduce a local drug or therapeutic ion release system into the implant site, which could lead to high delivery efficiency and reduced toxicity5,6.

A variety of biomaterials are used for bone tissue engineering applications, including bioactive glasses, that have the ability to react with body fluids and to form a layer of hydroxycarbonate apatite, which is chemically and structurally equivalent to the mineral phase in bone and is responsible for interfacial bonding78. In the same way, mesoporous materials have attracted great attention owing to their significant features of a large surface area, ordered mesoporous structure, tunable pore size and volume, and well-defined surface property. They have many potential applications, in catalysis, adsorption/separation process, and as carriers of therapeutic drugs and ions9. Additionally, different kinds of bioactive ions could be effectively released from mesoporous bioactive glasses with a controlled release kinetics6.

In the framework of this research project, 45S5 Bioglassâ scaffolds with enhanced mechanical properties were prepared via the foam replica technique using natural marine sponges as sacrificial templates. The goal of the integration of an ordered mesoporous glass coating doped with silver ions was to provide antibacterial properties to the system. Porosity of around 79 % and 76 % before and after the coating were obtained respectively. The coated scaffolds showed high bioactive behaviour and compressive strength of ~4 MPa and after four weeks of immersion in SBF ~1.2 MPa.

The antibacterial activity of the scaffolds was assessed and exhibited a larger bacterial inhibition area after three days of immersion in SBF against E.coli than against S.carnosus bacteria. Preliminary cell studies confirm that cells can grow and attach to scaffolds struts on both the inhalant and exhalant surfaces.

Results obtained in this thesis suggest that marine sponge-derived bioactive glass based scaffolds coated with silver doped mesoporous glass are promising structures for bone regeneration applications due to their release of active molecules and antibacterial ions.

A graphical summary of the research conducted in the framework of this thesis is shown below.

References:
1. Amini, A. R., Laurencin, C. T. & Nukavarapu, S. P. Bone Tissue Engineering: Recent Advances and        Challenges. Crit. Rev. Biomed. Eng. 40, 363–408 (2012).

2. Baroli, B. From natural bone grafts to tissue engineering therapeutics: Brainstorming on pharmaceutical formulative requirements and challenges. Journal of Pharmaceutical Sciences 98, 1317–1375 (2009).

3. Jones, J. R., Ehrenfried, L. M. & Hench, L. L. Optimising bioactive glass scaffolds for bone tissue engineering. Biomaterials 27, 964–973 (2006).

4. Langer, R. & Vacanti, J. P. Tissue engineering. Science 260, 920–6 (1993).

5. Mourino, V. & Boccaccini, A. R. Bone tissue engineering therapeutics: controlled drug delivery in three-dimensional scaffolds. J. R. Soc. Interface 7, 209–227 (2010).

6. Wu, C. & Chang, J. Multifunctional mesoporous bioactive glasses for effective delivery of therapeutic ions and drug/growth factors. J. Control. Release 193, 282–295 (2014).

7 .Philippart, A. Design and development of mesoporous glass- based biomaterials for bone tissue engineering and drug release systems. 1–154 (2016).

8. Jones, J. R. Reprint of: Review of bioactive glass: From Hench to hybrids. Acta Biomaterialia 23, S53–S82 (2015).

9. .Wu, C. & Chang, J. Mesoporous bioactive glasses: structure characteristics, drug/growth factor delivery and bone regeneration application. Interface Focus 2, 292–306 (2012).