Regulating
cell migration dynamics is of significance in tissue
engineering and regenerative medicine. A 3D scaffold was created to
provide various topographies based on a poly(ε-caprolactone)
(PCL) self-induced nanohybrid shish-kebab structure, which consisted
of aligned PCL nanofibers and spaced PCL crystal lamellae grown on
the fibers. Electrospinning was applied followed by self-induced crystallization.
The results resembled natural collagen fibrils in an extracellular
matrix. This variable microstructure enabled control of cell adhesion
and migration. The kebab size was controlled by initial PCL concentrations.
The geometry of cells seeded on the fibers was less elongated, but
the adhesion was more polarized with a higher nuclear shape index
and faster migration speed. These results could aid in rapid endothelialization
in tissue engineering.
Polytetrafluoroethylene
(PTFE) is one of the polymers extensively applied in biomedicine.
However, the application of PTFE as a small-diameter vascular graft
results in thrombosis and intimal hyperplasia because of the immune
response. Therefore, improving the biocompatibility and anticoagulant
properties of PTFE is a key to solving this problem. In this study,
a hydroxyl group-rich surface was obtained by oxidizing a benzoin-reduced
PTFE membrane. Then, chondroitin sulfate (CS), an anticoagulant, was
grafted on the surface of the hydroxylated PTFE membrane using 3-aminopropyltriethoxysilane.
The successful modification of the membrane in each step was demonstrated
by Fourier transform infrared spectroscopy and X-ray photoelectron
spectroscopy. Hydroxylation and the grafting of CS greatly increased
the hydrophilicity and roughness of membrane samples. Moreover, the
hydroxylated PTFE membrane enhanced the adhesion ability of endothelial
cells, and the grafting of CS also promoted the proliferation of endothelial
cells and decreased platelet adhesion. The results indicate that the
PTFE membranes grafted with CS are able to facilitate rapid endothelialization
and inhibit thrombus formation, which makes the proposed method outstanding
for artificial blood vessel applications.
Despite their immiscibility, blending polylactic acid (PLA) with poly(ε-caprolactone) (PCL) provides an efficient strategy for obtaining a biopolymer blend with tailored properties due to their complementary physical properties. In this study, graphene oxide (GO) was employed as a 2-D nanofiller and nucleating agent to improve the properties of the immiscible PLA/PCL blends at 70/30, 50/50, and 30/70 weight ratios. Nanofibers of PLA/PCL blends and PLA/PCL/GO composites were investigated. It was interesting to find that the GO selectively localized in the minor phase resulting from the phase separation. The selective localization of the GO as the nucleating agent had an influence on the degree of crystallinity and crystalline morphology in the blended composites. This study also demonstrated that the molecular chains in the PLA phase oriented along the fiber axes, while in the PCL phase, the partial crystallites changed their orientation direction to be perpendicular to the fiber axes with the addition of GO.
In tissue engineering applications, a scaffold containing an interconnected porous structure is often highly desirable since these interconnected pores allow nutrients and signaling molecules to reach all of the cultured cells. In this study, microcellular injection molding, a mass production method for foamed plastic components, was combined with chemical foaming and particulate leaching methods to fabricate an interconnected porous structure using poly(ɛ-caprolactone) (PCL). Sodium bicarbonate (SB) was employed as the chemical foaming agent while carbon dioxide (CO2) was used as the physical foaming (blowing) agent. The results showed that interconnected porous structures of PCL, which depend on the composition of the materials used, could be successfully produced. Sodium bicarbonate not only generated CO2 to supplement the supercritical fluid microcellular injection molding, but also served as the nuclei for heterogeneous cell nucleation. Sodium bicarbonate and its byproduct, sodium carbonate, were also the porogens in the particulate leaching process, which further enhanced the porosity and interconnectivity. The morphologies and mechanical properties of the samples with different material compositions and porosities were discussed. The results of cell viability assays of 3T3 fibroblasts suggested that the resulting interconnected porous PCL scaffolds exhibited good biocompatibility. Cell spreading was affected by the porosity of the scaffold because of the physical restriction effect on the cell migration. Highly improved interconnectivity of the scaffold provided more space for the cells to spread.
The shish–kebab structure has been extensively applied in many fields; however, the formation mechanism is still an open question. In this study, different electrospun poly(ε‐caprolactone) (PCL) fibers are applied as the shish material in a self‐induced crystallization process, and two different self‐induced crystal structures are obtained. The PCL fibers with an ordered crystalline morphology lead to an induced crystalline structure with the crystal lamellae perpendicular to the fiber axis. However, the PCL fibers with a disordered structure induce a complicated (less ordered) crystalline lamellae morphology. Investigation of the surface crystalline structure reveals that the self‐induced nanohybrid shish–kebab (SINSK) structure follows a lattice matching and epitaxial growth mechanism. The internal crystalline structure of PCL nanofibers plays a dominant role in the formation of the SINSK structure. This study may prove helpful in screening materials for formation of the SINSK structure.
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