Citation: Almeida, S.D.; Silva, J.C.; Borges, J.P.M.R.; Lança, M.C. Characterization of a Biocomposite of Electrospun PVDF Membranes with Embedded BaTiO 3 Micro- and Nanoparticles. Macromol 2022, 2, 531–542. https://doi.org/10.3390/ macromol2040034 Academic Editor: Dimitrios Bikiaris Received: 21 September 2022 Accepted: 14 November 2022 Published: 17 November 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Article Characterization of a Biocomposite of Electrospun PVDF Membranes with Embedded BaTiO 3 Micro- and Nanoparticles Sérgio D. Almeida 1 , Jorge C. Silva 2 , João P. M. R. Borges 1, * and M. Carmo Lança 1, * 1 CENIMAT|i3N, Departmentof Materials Science, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal 2 CENIMAT|i3N, Department of Physics, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal * Correspondence: jpb@fct.unl.pt (J.P.M.R.B.); mcl@fct.unl.pt (M.C.L.) Abstract: Damage to bone tissue is a common health issue that tends to increase in severity with age and other underlying conditions. To take advantage of the piezoelectric effect on bone remodulation, piezoelectric materials can be used to fill patients bone defects. Polyvinylidene fluoride (PVDF) and barium titanate (BaTiO 3 ) are both well-known polymeric and ceramic biomaterials, respectively, as well as piezoelectric at room temperature. To mimic the extracellular matrix, PVDF membranes were produced by electrospinning onto a rotating drum to promote the alignment of fibers and micro- and nano-sized tetragonal BaTiO 3 particles were embedded into these membranes to try to enhance the piezoelectric response and, therefore, bioactivity. After defining the best deposition parameters to produce pure PVDF membranes, the same parameters were carried over for the embedded membranes and both were characterized, revealing that the proposed method for obtaining β- phase PVDF (the polymer phase with highest piezoelectric coefficient) through electrospinning is viable, producing fibers with coherent diameters and alignment. The presence of barium titanate conferred bioactivity to the membranes and caused a decrease in fibers’ diameter and in superficial charge density. Keywords: PVDF; electrospinning; piezoelectricity; BaTiO 3 ; bone regeneration; functional biomaterials 1. Introduction Bone tissue regeneration is unique as it leaves, in many situations, no scar tissue unlike other processes of tissue regeneration, so the new tissue is in no way inferior and indistin- guishable to the preceding tissue. Old age and several serious health conditions cause the regenerative capabilities of the bone tissue to be diminished leading to significant losses of bone mass. This aggravates the possibility of fractures or injuries to occur. Furthermore, recovery needs more time to fully grow and heal the fractured bone, and the frequency of impaired healing caused by misalignments and other factors tends to be higher, causing a great decrease in life quality of the patients [1,2]. Bone is not a homogenous tissue, being composed mainly of living cells inside a biomineral medium made of 30% organic segments and 70% inorganic segments, while the organic part of the biomineral medium is composed of 90% collagen fibers. On the other hand, the inorganic segment is composed of hexagonal hydroxyapatite crystals (Ca 10 (PO 4 ) 6 (OH) 2 ) that can attract free ions of Ca 2+ and (PO 4 ) 3− in the body through electrostatic and surface-binding interactions. Throughout the years, a substantial number of different strategies have been developed and investigated that can be divided into three main, often overlapping, strategies: synthetic substitutes, scaffolds, and functionalized materials. The process of bone regrowing has been reported to be linked to its piezoelectric properties [3–6] as the mechanical stress applied to the skeletal structure from everyday movement creates electrical signals for cells to initiate bone remodelling. Consequently, a validated strategy for enhancing bone Macromol 2022, 2, 531–542. https://doi.org/10.3390/macromol2040034 https://www.mdpi.com/journal/macromol