## 4 Conclusions  
Both electrospinning and 3D-printing technologies can be mixed to obtain composites meeting requirements for tissue engineering. By computer-assisted design it was possible to obtain scaffolds with a controlled pore shape that are easily printable in commercial 3D-printers working with PLA-based filaments and a well-known biocompatible and biodegradable polymer. The 3D-printer filament was also used to obtain the polymer  
Figure 12: MTT assay for cells after contact with 3D-printed/electrospun ellipsoidal (**I**) and square (**II**) composites. A control sample is a composite prepared without cover over the surface of 3D-printed pieces with fibers; and A-D are those prepared with PLA-based fibers: (A) PLA10, (B) PLA/PEG, (C) PLA/PEG/2.5 HA, and (D) PLA/PEG/5.0 HA.  
Figure 13: Selected SEM images of 3D-printed/electrospun composites cultured for 5 days with 3T3 cells. Fibroblast adhered to the 3D-printed piece are showed in (**A**,**B**). ((**A**) is a square 3D-printed/electrospun composite with PLA10 fibers, and (**B**) is the ellipsoidal composite with PLA/PEG/5.0 HA fibers). The fibroblasts which adhered to the fibrous layer of the composite are showed in (**C**,**D**). ((C) is an ellipsoidal composite with PLA10 fibers, and (**D**) is a square composite with PLA/PEG/5.0 HA fibers).  
used to prepare porous fibers by electrospinningning, and the mechanical, morphological, and wettability properties of these fibers is improved by adding small amounts of PEG and HA as additives. A composite was obtained after mixing two layers of 3D-printed scaffolds with a central layer of PLA-based fibers. These composites showed a reduced storage modulus as compared with bare 3D-printed pieces; thus, a soft composite is obtained after blending 3D-printed pieces with electrospun fibers. The culture of these composites with 3T3 cells showed a high cell viability in those prepared with 3D-printed/electrospun composites possessing an ellipsoidal pore shape, and cells were able to attach and grow both over the surface of the 3D-printed layer and electrospun fibers. The results presented in this work shows the potential of commercial PLA 3D-printer filaments to obtain biocompatible and biomimetic composites to be used in bone tissue engineering.  
The following are available online at [[https://www.mdpi.com/article/10.3390/polym13213806/s1](https://www.mdpi.com/article/10.3390/polym13213806/s1)]([https://www.mdpi.com/article/10.3390/polym13213806/s1](https://www.mdpi.com/article/10.3390/polym13213806/s1)), Figure S1: TEM of HA; Figure S2: SEM-EDS analysis of HA; Table S1: Reagents used to prepare SBF media; Table S2: Ca/P ratio analysis for samples in SBF assay obtained from SEM-EDS measurements.  
Conceptualization, P.R.-A., V.P., G.S. and M.E.F.; methodology, P.R.-A., V.P., A.N., V.C., F.P. and M.E.F.; software, P.R.-A., V.P., G.S. and M.E.F.; validation, P.R.-A., V.P. and M.E.F.; formal analysis, P.R.-A. and M.E.F.; investigation, M.E.F.; resources, G.S., F.P., P.E., I.M.-V., J.G.L. and M.E.F.; data curation, P.R.-A. and M.E.F.; writing--original draft preparation, P.R.-A. and M.E.F.; writing--review and editing, P.R.-A., V.P., A.N., V.C., F.P., P.E., G.S., J.G.L., I.M.-V. and M.E.F.; supervision, M.E.F.; project administration, M.E.F.; funding acquisition, M.E.F. All authors have read and agreed to the published version of the manuscript.  
This research was funded by ANID FONDECYT, grant number 11181029. Also, the authors thank the support of project Millennium Nucleus MULTIMAT, ICM-MINECON. This paper is based on a thesis submitted by [PERSON] and [PERSON] in partial fulfillment of the requirements for the degree of Bachelor in Dental Surgery in the School of Dentistry of the Universidad Austral of Chile in October 2021.  
We acknowledge to Unidad de Microscopia Electronica (UME) from Vicerrectoria de Investigacion y Crecacion Artistica, Universidad Austral de Chile, for the support printed in sample preparation and visualization by SEM.  
The authors declare no conflict of interest.