Accelerating the excisional wound closure by using the patterned microstructural nanofibrous mats/gentamicin-loaded hydrogel composite scaffold.

Ideal artificial tissue scaffolds should provide an in vitro microenvironment comparable to native human skin tissue to direct cell functions, regulate tissue homeostasis, and promote tissue regeneration. A sandwich-like composite scaffold consisting of a hydrogel layer and two aligned nanofibre layers was fabricated and applied as a wound-healing dressing. Gentamicin was preloaded into the hydrogel middle layer and naturally released for antibacterial activity during the healing period. Nanofibrous layers embedded on the top and bottom surfaces of the hydrogel improved the tensile strength fivefold (1560 â€‹kPa and 465% strain) while serving as a diffusion barrier to reduce the gentamicin initial burst release (30%-15%). Inspired by the extracellular matrix (ECM), the surface of nanofibre top layer was patterned with triangular microarrays using micro-moulding approach to reflect the multidimensional structure of ECM. Biocompatibility of the scaffold is proven from cytotoxicity and haemolysis studies. Fibroblast cells revealed a highly elongated and consistent alignment modulated by the micropatterned fibrous layer and directed their migration towards the wound area. Excisional wounds treated with the scaffold promoted 97.49% wound closure with low inflammation and rapid re-epithelialization and angiogenesis. This scaffold, with its tailored functionality capable of accelerating wound healing, has high potential in tissue engineering applications.

Controlling cell elongation and orientation by using microstructural nanofibre scaffolds for accelerating tissue regeneration.

The topographic surface conditions of scaffolds can regulate cellular behaviours, such as by stimulating cellular migration and morphological changes to wound sites and have the potential to promote tissue regeneration. In this research, four types of engineered topographic surfaces, including arrays of hemisphere, pyramid, semi-cylinder, and triangle prism microstructures, were patterned on silicon moulds using microfabrication processes. The microstructural patterns were transferred onto the surface of polycaprolactone membranes and nanofibrous scaffolds by combining with the moulding approach and electrospinning technique, respectively. In vitro experimental results demonstrated that the triangular microstructural nanofibre provided a strong guiding performance to the filopodia of cultured C2C12 myoblast cells, thus inducing cellular elongation and alignment in the longitudinal direction and forming an elongated cell morphology. The cultured cells rapidly transitioned into an elongated morphology at an aspect ratio of 17.33 after 24 h of incubation, with 70% of the cell elongates aligning with the direction of triangular microstructural patterns. The cells cultured on the triangular microstructural nanofibre elongated four-fold compared with those in the flat nanofibre scaffold. Moreover, an in vivo study showed that wounds treated with the triangular microstructural nanofibre scaffold achieved 95.04% wound closure after 14 days and completed the reepithelialisation with an ordered collagen arrangement. Therefore, we believe that the engineered triangular nanofibrous scaffold may accelerate tissue regeneration and has potential for wound healing applications.

Development of Thermo-Responsive Polycaprolactone-Polydimethylsiloxane Shrinkable Nanofibre Mesh.

A thermally activated shape memory polymer based on the mixture of polycaprolactone (PCL) and polydimethylsiloxane (PDMS) was fabricated into the nanofibre mesh using the electrospinning process. The added percentages of the PDMS segment in the PCL-based polymer influenced the mechanical properties. Polycaprolactone serves as a switching segment to adjust the melting temperature of the shape memory electro-spun PCL-PDMS scaffolds to our body temperature at around 37 °C. Three electro-spun PCL-PDMS copolymer nanofibre samples, including PCL6-PDMS4, PCL7-PDMS3 and PCL8-PDMS2, were characterised to study the thermal and mechanical properties along with the shape memory responses. The results from the experiment showed that the PCL switching segment ratio determines the crystallinity of the copolymer nanofibres, where a higher PCL ratio results in a higher degree of crystallinity. In contrast, the results showed that the mechanical properties of the copolymer samples decreased with the PCL composition ratio. After five thermomechanical cycles, the fabricated copolymer nanofibres exhibited excellent shape memory properties with 98% shape fixity and above 100% recovery ratio. Moreover, biological experiments were applied to evaluate the biocompatibility of the fabricated PCL-PDMS nanofibre mesh. Owing to the thermally activated shape memory performance, the electro-spun PCL-PDMS fibrous mesh has a high potential for biomedical applications such as medical shrinkable tubing and wire.

Temporary Wettability Tuning of PCL/PDMS Micro Pattern Using the Plasma Treatments.

Surface wettability plays an important role in determining the function of a wound dressing. Dressings with hydrophobic surfaces are suitable for bacterial adsorption, however, a hydrophilic surface is needed to improve cell attachment for most anchorage-dependent cell types. Furthermore, the hydrophobicity/hydrophilicity of the surface can be used to direct cellular processes such as cell initial attachment, adhesion, and migration during wound healing. Thus, a surface with an ability to switch their surface wettability improves the practicality of the dressing. In this study, we propose a temporary surface wettability tuning for surface patterning utilizing plasma treatment. Polycaprolactone (PCL) and polydimethylsiloxane (PDMS) surfaces were treated with tetrafluoromethane (CF4), sulphur hexafluoride (SF6), and oxygen (O2) plasma, and the effects on the surface wettability, roughness, and chemical composition were investigated. Based on the contact angle measurement, CF4 plasma altered surface wettability of PCL and PDMS films to hydrophobic and hydrophilic, respectively. After CF4 treatment, better attachment of primary mouse embryonic fibroblast cell (3T3) was observed on the treated PDMS surface. Embedding PCL into PDMS generated a hydrophobic-hydrophilic pattern mixture surface, which offers great potential in the tissue engineering field such as cell patterning and guidance.