Ferulic acid-loaded collagen hydrolysate and polycaprolactone nanofibres for tissue engineering applications

There is a great need for the progress of composite biomaterials, which are effective for tissue engineering applications. In this work, the development of composite electrospun nanofibres based on polycaprolactone (PCL) and collagen hydrolysate (CH) loaded with ferulic acid (FA) for the treatment of chronic wounds. Response Surface Methodology (RSM) has been applied to nanofibres factor manufacturing assisted by electrospinning. For wound healing applications, the authors have created the efficacy of CH, and PCL membranes can act as a stable, protective cover for wound, enabling continuous FA release. The findings of the RSM showed a reasonably good fit with a polynomial equation of the second order which was statistically acceptable at P < 0.05. The optimised parameters include the quantity of hydrolysate collagen, the voltage applied and the distance from tip-to-collector. Based on the Box-Behnken design, the RSM was used to create a mathematical model and optimise nanofibres with minimum diameter production conditions. Using FTIR, TGA and SEM, optimised nanofibres were defined. In vitro, cytocompatibility trials showed that there was an important cytocompatibility of the optimised nanofibres, which was proved by cell proliferation and cell morphology. In this research, the mixed nanofibres of PCL and CH with ferulic could be a potential biomaterial for wound healing.

Performance Optimization of Polymer Fibre Actuators for Soft Robotics

Analytical modeling of soft pneumatic actuators constitutes a powerful tool for the systematic design and characterization of these key components of soft robotics. Here, we maximize the quasi-static bending angle of a soft pneumatic actuator by optimizing its cross-section for a fixed positive pressure inside it. We begin by formulating a general theoretical framework for the analytical calculation of the bending angle of pneumatic actuators with arbitrary cross-sections, which is then applied to an actuator made of a circular polymer tube and an asymmetric patch in the shape of a hollow-cylinder sector on its outer surface. It is shown that the maximal bending angle of this actuator can be achieved using a wide range of patches with different optimal dimensions and approximately the same cross-sectional area, which decreases with pressure. We also calculate the optimal dimensions of thin and small patches in thin pneumatic actuators. Our analytical results lead to clear design guidelines, which may prove useful for engineering and optimization of the key components of soft robotics with superior features.

UV cross-linked polyvinylpyrrolidone electrospun fibres as antibacterial surfaces

Many bacteria become progressively more resistant to antibiotics and it remains a challenging task to control their overall levels. Polymers combined with active biomolecules come to the forefront for the design of antibacterial materials that can address this encounter. In this work, we investigated the photo-crosslinking approach of UV-sensitive benzophenone molecule (BP) with polyvinylpyrrolidone (PVP) polymer within electrospun fibres. The BP and PVP solutions allowed fabricating polymer mats that were subsequently functionalised with antibacterial lysozyme. The physical properties of the crosslinked electrospun fibres were investigated by scanning electron microscopy and atomic force microscopy. The average diameter of the obtained fibres decreased from 290 ± 50 nm to 270 ± 70 nm upon the addition of the crosslinking molecules and then to 240 ± 80 nm and 180 ± 90 nm after subsequent crosslinking reaction at an increasing time: 3 and 5 h, respectively. The peak force quantitative nanomechanical mapping (PF-QNM) indicated the increase of DMT modulus of obtained cross-linked fibres from 4.1 ± 0.8 GPa to 7.2 ± 0.5 GPa. Furthermore, the successful crosslinking reaction of PVP and BP solution into hydrogels was investigated in terms of examining photo-crosslinking mechanism and was confirmed by rheology, Raman, Fourier transform infrared and nuclear magnetic resonance. Finally, lysozyme was successfully encapsulated within cross-linked PVP-BP hydrogels and these were successfully electrospun into mats which were found to be as effective antibacterial agents as pure lysozyme molecules. The dissolution rate of photo cross-linked PVP mats was observed to increase in comparison to pure PVP electrospun mats which opened a potential route for their use as antibacterial, on-demand, dissolvable coatings for various biomedical applications.

Poly (ɛ-caprolactone)-chitosan-poly (vinyl alcohol) nanofibrous scaffolds for skin excisional and burn wounds in a canine model

Poly (ɛ-caprolactone)-chitosan-poly (vinyl alcohol) (PCL: Cs: PVA) nanofibrous blend scaffolds were known as useful materials for skin wound healing and would help the healing process about 50% faster at the final time point. From the previous studies by the authors, PCL: Cs: PVA (in 2: 1: 1.5 mass ratio) nanofibres showed high efficacy in healing on rat models. In this study, the scaffolds were examined in burn and excision wounds healing on dogs as bigger models. The scaffolds were applied on dorsum skin wounds (n = 5) then macroscopic and microscopic investigations were carried out to measure the wounds areas and to track healing rate, respectively. Macroscopic results showed good aspect healing effect of scaffolds compared with control wounds especially after 21 days post-operating for both cutting and burn wounds. Pathological studies showed that the healing rates of the wounds covered with PCL: Cs: PVA nanofibrous scaffolds were much rapid compared to untreated wounds in control group. The immunogenicity of the scaffolds in canine model was also investigated. The findings showed that nanofibrous blend scaffolds was not immunogenic in humoural immune responses. All these results indicated that PCL: Cs: PVA nanofibrous web could be considered as promising materials for wounds healings.