*Article* **Composite Fibers Based on Polycaprolactone and Calcium Magnesium Silicate Powders for Tissue Engineering Applications**

**Cristina Busuioc <sup>1</sup> , Andrada-Elena Alecu 1, Claudiu-Constantin Costea 1, Mihaela Beregoi <sup>2</sup> , Mihaela Bacalum <sup>3</sup> , Mina Raileanu 3, Sorin-Ion Jinga <sup>1</sup> and Iuliana-Mihaela Deleanu 1,\***

	- <sup>2</sup> National Institute of Materials Physics, RO-077125 Magurele, Romania
	- <sup>3</sup> National Institute of Physics and Nuclear Engineering, RO-077125 Magurele, Romania
	- **\*** Correspondence: iuliana.deleanu@upb.ro

**Abstract:** The present work reports the synthesis and characterization of polycaprolactone fibers loaded with particulate calcium magnesium silicates, to form composite materials with bioresorbable and bioactive properties. The inorganic powders were achieved through a sol–gel method, starting from the compositions of diopside, akermanite, and merwinite, three mineral phases with suitable features for the field of hard tissue engineering. The fibrous composites were fabricated by electrospinning polymeric solutions with a content of 16% polycaprolactone and 5 or 10% inorganic powder. The physico-chemical evaluation from compositional and morphological points of view was followed by the biological assessment of powder bioactivity and scaffold biocompatibility. SEM investigation highlighted a significant reduction in fiber diameter, from around 3 μm to less than 100 nm after the loading stage, while EDX and FTIR spectra confirmed the existence of embedded mineral entities. The silicate phases were found be highly bioactive after 4 weeks of immersion in SBF, enriching the potential of the polymeric host that provides only biocompatibility and bioresorbability. Moreover, the cellular tests indicated a slight decrease in cell viability over the short-term, a compromise that can be accepted if the overall benefits of such multifunctional composites are considered.

**Keywords:** polycaprolactone; diopside; akermanite; merwinite; electrospinning; bone scaffolds
