Study of polylactide matrices using x-ray microtomography

Three-dimensional matrices of biodegradable polymers are promising materials for regenerative medicine. They are widely used in restoring the integrity and functions of tissues and organs using bio-artificial tissue engineering structures. We present the results of studying the structure of porous bioresorbable polymer matrices for tissue engineering using X-ray microtomography. Samples were obtained by supercritical fluid plasticization of D,L-polylactide with subsequent foaming in cylindrical molds. The tomographic method makes it possible to construct a three-dimensional voxel model of the object under study and gain apart from the estimate on the integral matrix porosity (characteristic data obtained by traditional sorption procedures) additional information about the size and spatial distribution of pores thus providing a possibility of optimization of the process parameters for production of polylactide matrices required for specific biomedical applications of architectonics, as well as forecasting the processes of their bioresorption in enzymatic media. The experiments were carried out on a laboratory microtomograph (Mo anode, the scan time of the sample is 120 min, the detector pixel size is 9 μm). Tomographic reconstruction was performed by algebraic method. The binarization procedure required for calculation of the structural characteristics of studied matrices was implemented by the method with the choice of a global threshold. Calculations of the porosity and homogeneity of the porosity distribution in the bulk, as well as estimation of the specific surface area of pores revealed the isotropy of the spatial structure of polylactide matrices.

1. Sevastianov V. I. Technologies of tissue engineering and regenerative medicine / Vestn. Transplantol. Iskusstv. Organov. 2014. Vol. XVI. N 3. P. 93 – 108 [in Russian].

2. Biocompatible materials / Ed. by Sevastianov V. I., Kirpichnikov M. P. — Moscow: MIA, 2011. — 544 p. [in Russian].

3. Surguchenko V. A. The matrices for tissue engineering and hybrid organs. Biocompatible materials. — Moscow: MIA, 2011 [in Russian].

4. Antonov E. N., Bukharova T. B., Dunaev A. G., et al. New «old» polylactides for tissue engineering constructions / Perspekt. Mater. 2017. N 2. P. 14 – 25 [in Russian].

5. Karageorgiou V., Kaplan D. Porosity of 3D biomaterial scaffolds and osteogenesis / Biomaterials. 2005. Vol. 26. N 27. P. 5474 – 5491.

6. Tai H., Popov V., Shakesheff K., Howdle S. Putting the fizz into chemistry: applications of supercritical carbon dioxide in tissue engineering, drug delivery and synthesis of novel block copolymers / Biochemical Society Transactions. 2007. Vol. 35. P. 516 – 521.

7. Bogorodski S. E., Krotova L. I., Mironov A. V., Popov V. K. Fabrication of highly porous bioresorbable polymer matrices using supercritical carbon dioxide / Russ. J. Physical Chemistry B. 2013. Vol. 7. N 8. P. 916 – 923.

8. Bogorodski S. E., Vasilets V. N., Krotova L. I., Minaeva S. A., Mironov A. V., Nemets E. A., Surguchenko V. A., Popov V. K., Sevastianov V. I. Fabrication of bioactive highly porous polymer matrixes for tissue engineering / Inorganic Materials: Applied Research. 2013. Vol. 4. N 5. P. 448 – 456.

9. Buzmakov A. V., Asadchikov V. E., Zolotov D. A., et al. Laboratory Microtomographs: Design and Data Processing Algorithms / Crystallography Reports. 2018. Vol. 63. N 6. P. 1057 – 1061.

10. Chukalina M. V., Buzmakov A. V., Senin R. A., et al. Optophysical measurements: X-ray microtomography using a laboratory source: measurement technique and comparison of reconstruction algorithms / Measurement techniques. 2008. Vol. 51. N 2. P. 136 – 145.

11. Buzmakov A. V., Asadchikov V. E., Zolotov D. A., et al. Laboratory X-ray Microtomography: Ways of Processing Experimental Data / Bull. RAS. Phys. 2019. Vol. 83. N 2. P. 146 – 149.

12. Saltykov S. A. Stereometric metallography. — Moscow: Metallurgiya, 1976. — 270 p. [in Russian].

13. Burnaev E., Erofeev P., Papanov A. Influence of resampling on accuracy of imbalanced classification / Proc. SPIE 9875. 8th International Conference on Machine Vision (ICMV 2015). 2015. 987521.