Comparative Study on Bioactive Filler/Biopolymer Scaffolds for Potential Application in Supporting Bone Tissue Regeneration

Abstract

The combination of biopolymers and bioactive inorganic particles for bone tissue regeneration has been investigated in the last decades. However, several studies report discordant results on the specific synergistic effect of the compounds. A comparative study on porous scaffolds obtained by the combination of the most promising biopolymers and bioactive inorganic particles is herein reported. Specifically, porous scaffolds have been fabricated by the Thermally Induced Phase Separation method using poly­(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly­(lactic acid) (PLA), and poly­(caprolactone) (PCL) compounded with hydroxyapatite (HAp), calcium silicate (CS), or a Mg- and Sr-rich bioglass (BG) with a nominal composition of 2.3% Na2O, 2.3% K2O, 25.6% CaO, 10.0% MgO, 10.0% SrO, 2.6% P2O5, and 47.2% SiO2. Morphological analyses revealed the formation of highly interconnected and aligned open pores. Both thermal investigations and compressive tests highlight the close similarity between PLA- and PHBV-based scaffolds in terms of the amorphous structure and stiffness when the fillers are added. On the other hand, the addition of amorphous BG in semicrystalline PCL shows a decrease of the crystallinity degree of the polymer and a consequent decrease of the compressive modulus. Preliminary in vitro investigations (direct and indirect contact tests) carried out on the composite systems revealed that all the prepared materials provide an appropriate environment for NIH 3T3 cell adhesion and proliferation, showing a total lack of cytotoxicity. The addition of all the inorganic fillers has an overall positive effect on cell proliferation, viability (Neutral Red uptake), and metabolic activity (MTT test). Interestingly, this effect is particularly evident whenever BG is added. The combination of both amorphous BGs with amorphous polymers, such as PLA and PHBV, seems to be responsible for creating the best microenvironmental cue for NIH 3T3 cell attachment and proliferation.

Further Step in the Transition from Conventional Plasticizers to Versatile Bioplasticizers Obtained by the Valorization of Levulinic Acid and Glycerol

“…In detail, PVC and PLA were initially solubilized in THF (0.67 mg·mL –1 ), whereas PHB, PHBV, and PCL were solubilized in CHCl 3 (0.67 mg·mL –1 ). All polymeric solutions were then vacuum-filtered on Celite and precipitated in a large excess of cold methanol, according to the procedure reported elsewhere …”

“…All polymeric solutions were then vacuum-filtered on Celite and precipitated in a large excess of cold methanol, according to the procedure reported elsewhere. 48 Synthesis of Glycerol Trilevulinate Plasticizer. The solvent-free synthesis of glycerol trilevulinate (GT) plasticizer was carried out in mild conditions by esterifying LA with GLY.…”

Fine Tuning of the Mechanical Properties of Bio-Based PHB/Nanofibrillated Cellulose Biocomposites to Prevent Implant Failure Due to the Bone/Implant Stress Shielding Effect

“…PHB was purchased from Sigma Aldrich (custom synthesis, M n 71,600, M w 245,100, Milan, Italy) and carefully purified in order to remove impurities before the preparation of the copolymer (detailed procedure described elsewhere [ 10 ]). PEG 4000 (PEG, synthesis grade) was purchased from Scharlau and PEG 1900 monomethyl ether (mPEG) was purchased from Alfa Aesar (Kandel, Germany), and both were used as received.…”

“…Emerging biomaterials for bone replacement and regeneration are entering the orthopedic field thanks to their set of physical, chemical, and biological properties that allow them to achieve the appropriate function, in addition to actively stimulating the desired tissue response, thus making the recovery more rapid and efficient [ 6 , 8 ]. Among them, biocompatible and bioresorbable polymer-based materials [ 9 , 10 ] can be easily 3D-manufactured in order to fabricate a patient-specific replacement of the injured area. Furthermore, polymers show easily tunable mechanical properties and, thanks to their bioresorbability, a second surgery can be avoided since the implanted material is resorbed by the body [ 9 ].…”

Sustainable PHBV/CuS Composite Obtained from Waste Valorization for Wastewater Purification by Visible Light‐Activated Photocatalytic Activity

“…For this reason, in this work, we have combined a biopolymeric supporting material for CuS particles as a visible-lightdriven photocatalyst for enhancing organic molecules degradation. Specifically, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) has been selected as supporting material, since it is one of the most promising and versatile biopolymers [24] with several potential applications [25][26][27][28][29] thanks to its higher ductility with respect to its homopolymers poly(3-hydroxybutyrate). [30] Moreover, PHBV is a fully bio-based and biodegradable polymer, that can be obtained by fermentation of vegetable waste.…”