Novel three‐dimensional scaffolds of poly(L‐lactic acid) microfibers using electrospinning and mechanical expansion: Fabrication and bone regeneration

Abstract

Poly(L-lactic acid) (PLLA) microfibrous scaffolds with three-dimensional (3D) structures were fabricated using an electrospinning technique with a subsequent mechanical expansion process. To achieve a 3D fibrous structure, the fusion at the contact points of the as-spun PLLA microfibers was avoided using an appropriate binary solvent system of methylene chloride and acetone. The solvent composition was optimized based on the solvent power, volatility, and viscosity (methylene chloride:acetone = 9:1 volume ratio). The final 3D structure of the electrospun scaffolds was obtained after mechanical expansion of the electrospun microfibrous mats. The pore sizes of the scaffolds were controlled by varying the degree of expansion of the nonbonded microfibrous mats, and they were in the range of several microns up to 400 μm. The 3D scaffolds were examined for their morphological properties and their potential use for the proliferation of osteoblasts. Generally recognized electrospun 2D nanofibrous membranes were also tested in order to compare the cell behaviors using different scaffold geometries. The 3D scaffolds demonstrated a high level of osteoblast proliferation (1.8-fold higher than nanofibrous membranes in a week). The osteoblasts actively penetrated the inside of the 3D scaffold and showed a spatial cell distribution, as confirmed by SEM and H&E staining, while a monolayer formed in the case of the 2D nanofibrous membranes with limited cell infiltration. In vivo results further showed that 3D electrospun microfibrous matrices were a favorable substrate for cell infiltration and bone formation after 2 and 4 weeks, using a rabbit calvarial defect model. In this study, the 3D microfibrous PLLA scaffolds fabricated using electrospinning techniques might be an innovative addition to tissue engineering applications.

Direct laser writing-mediated generation of standardized topographies for dental implant surface optimization

“…The differentiation-promoting effects of three-dimensional growth of osteoblast (-like) cells induced by the presence of artificial 3D scaffolds have been demonstrated by others. [18][19][20] Since proper osteogenesis requires a delicate balance between proliferation and differentiation, further studies are needed to analyze the influence of our scaffolds on hallmarks of osteoblast differentiation, such as alkaline phosphatase activity, osteocalcin secretion, or hydroxyapatite deposition.…”

Biodegradable polymers for dental tissue engineering and regeneration

“…Then, PLLA is modified or copolymerized with other degradable polymers to reduce degradation time, as shown by the use of radiations to create radicals in the ester alpha carbon which, upon rearrangement, shortens the polymer backbone through the removal of an ester bond and the release of carbon dioxide [100,101]. PLLA is used as bone fixator, scaffold for bone [102,103], cartilage [104], tendon [105], neural [106], and vascular [107] regeneration. Similarly, PDLLA is an amorphous polymer with the random positions of its two isomeric monomers within the polymer chain.…”

Recent Applications of Coaxial and Emulsion Electrospinning Methods in the Field of Tissue Engineering

“…Shim et al showed it is possible to modify sheets of nanofibers post-production to expand them into three dimensions. 130 Specifically, this group used a small metal comb to pull the nanofibers apart to decrease the overall nanofiber density and increase porosity of the PLLA scaffolds. Blakeney et al approached the dimensionality issue by modifying the nanofiber collector, altering the structure of a PCL nanofiber scaffold as the nanofibers were deposited.…”