Thermoplastic Polyurethane-Oleic Acid (TPU-OLE) Membranes for Guided Bone Regeneration

Abstract

Guided bone regeneration (GBR) is a regenerative surgical procedure in dentistry and orthopedics. The aim of this study is to fabricate a novel nano-textured, hydrophilic thermoplastic polyurethane (TPU)-based barrier membrane containing unsaturated fatty acid, oleic acid (OLE) to assist GBR. First, TPU copolymer containing OLE in different ratios was synthesized, and GBR membranes were fabricated by the solvent casting method, and then, the surface properties were improved by alkali treatment. Thus, a TPU-OLE structure was obtained with improved surface wettability, the ability to prevent bacterial adhesion, and the capability to promote cell adhesion. The contact angle reduced from 73.3° ± 1° to 30.7° ± 0.3° at TPU-OLE3, while at TPU it decreased from 121.2° ± 2.5° to 63.6° ± 0.8° after treatment with 3 M sodium hydroxide (NaOH) solution. Furthermore, plate counting assays showed that TPU-OLE membranes displayed excellent bacterial inhibition (against Escherichia coli and Staphylococcus aureus); the control group showed 6 × 10⁷ CFU/mL of E. coli bacterial colonies, while on the plates interacting with TPU-OLE1, TPU-OLE2, and TPU-OLE3 membranes, colonies of 12 × 10⁵, 12 × 10⁵, and 24 × 10⁵ CFU/mL were observed, respectively. The bacterial count on TPU-OLE1, TPU-OLE2, and TPU-OLE3 membranes decreased by 109, 164, and 12 × 10⁵ CFU/mL at 24 h, while the control group and TPU membranes showed 1300 × 10⁵ and 600 × 10⁵ CFU/mL, respectively. The obtained results indicated that either alkali treatment or OLE-modified TPU produced a more hydrophilic and promotive surface for cell attachment. Therefore, we anticipate that alkali-treated TPU-OLE membranes have a great potential in GBR in future applications.