*3.1. Morphology*

The morphology of ES PLA95/β-TCP fibrous membranes are shown in Figure 3. The average fiber diameter for this ES PLA95/β-TCP membrane was 2.37 ± 0.86 μm. The ES PLA95/β-TCP membranes were prepared using dip-coating technique with a dimension of 3.0 <sup>×</sup> 4.0 cm<sup>2</sup> (width <sup>×</sup> length), thickness of 0.3–0.4 mm, suture pull-out force of >200 gf, average porosity of 53.0 ± 4.5%, and average pore size of 25.0 ± 1.0 μm. Unlike the ES PLA95/β-TCP-N with contact angle of 122.6 ± 0.1◦, the PEO (polyethylene oxide) dip-coated ES PLA95/β-TCP-T revealed the contact angle of 50.7 ± 0.2◦ [22]. The hydrophilic surface would help cell adhesion to prevent the membrane expose and avoid infection during healing process.

The typical criteria for ideal GTR membranes are known as cell-occlusive, space making, tissue integrative, clinically manageable and biocompatible [23]. Among the fabrication processes electrospinning, a versatile physical processing technology that does not affect the inherent material properties, has substantially more advantages to manufacture membranes for biomedical and tissue-engineering applications due to their high surface area-to-volume ratio, porosity, and three-dimensional (3-D) structure to mimic an extracellular matrix for enhancing cell-surface interactions [24]. The fiber morphology and diameter of electro-spun poly lactic acid (PLA) fibers were mainly affected by solution properties and process parameters [25,26]. In recent years, growth factors [27–29], doxycycline [30,31], and bio-ceramic materials [32,33] have been incorporated into the GTR membranes to improve bioactivity and antibacterial properties. Hydroxyapatite (HAp), β-tricalcium phosphate (β-TCP), and calcium sulfate (CaSO4), are osteo-conductive bio-ceramics additives that are widely used in orthopedic and dental applications.

**Figure 3.** Scanning electron micrographs of the four electro-spun fibrous membranes: (**a**) ES PLA95-N, (**b**) ES PLA95-T, (**c**) ES PLA95/β-TCP-N and (**d**) ES PLA95/β-TCP-T. (N: Without polyethylene oxide (PEO) dip-coating treatment, T: PEO dip-coating treatment). Images courtesy of [22].

The control group chosen in this study is Epi-Guide®, a porous three-layer self-supporting poly-d,l-lactic acid (DL-PLA) barrier for up to 20 weeks with complete bio-resorption between 6–12 months. The Epi-Guide® barrier is claimed to be a hydrophilic membrane that quickly absorbs blood fluid and supports healthy clot formation to maintain gingival flap viability and coverage.
