Synthesis, electrospinning and in vitro test of a new biodegradable gelatin-based poly(ester urethane urea) for soft tissue engineering

Evaluation of Gelatin-Based Poly(Ester Urethane Urea) Electrospun Fibers Using Human Mesenchymal and Neural Stem Cells

Previously, a new biodegradable poly(ester urethane urea) was synthesized based on polycaprolactone-diol and fish gelatin (PU-Gel). In this work, the potential of this new material for neural tissue engineering is evaluated. Membranes with randomly oriented fibers and with aligned fibers are produced using electrospinning and characterized regarding their mechanical behavior under both dry and wet conditions. Wet samples exhibit a lower Young's modulus than dry ones and aligned membranes are stiffer and more brittle than those randomly oriented. Cyclic tensile tests are conducted and high values for recovery ratio and resilience are obtained. Both membranes exhibited a hydrophobic surface, measured by the water contact angle (WCA). Human mesenchymal stem cells from umbilical cord tissue (UC-MSCs) and human neural stem cells (NSCs) are seeded on both types of membranes, which support their adhesion and proliferation. Cells stained for the cytoskeleton and nucleus in membranes with aligned fibers display an elongated morphology following the alignment direction. As the culture time increased, higher cell viability is obtained on randomfibers for UC-MSCs while no differences are observed for NSCs. The membranes support neuronal differentiation of NSCs, as evidenced by markers for a neuronal filament protein (NF70) and for a microtubule-associated protein (MAP2).

Gelatin Meshes Enriched with Graphene Oxide and Magnetic Nanoparticles Support and Enhance the Proliferation and Neuronal Differentiation of Human Adipose-Derived Stem Cells

The field of tissue engineering is constantly evolving due to the fabrication of novel platforms that promise to stimulate tissue regeneration in the scenario of accidents. Here, we describe the fabrication of fibrous nanostructured substrates based on fish gelatin (FG) and enriched with graphene oxide (GO) and magnetic nanoparticles (MNPs) and demonstrate its biological properties in terms of cell viability and proliferation, cell adhesion, and differentiation. For this purpose, electrospun fibers were fabricated using aqueous precursors containing either only GO and only MNP nanospecies, or both of them within a fish gelatin solution. The obtained materials were investigated in terms of morphology, aqueous media affinity, tensile elasticity, and structural characteristics. The biological evaluation was assessed against adipose-derived stem cells by MTT, LDH, Live/Dead assay, cytoskeleton investigation, and neuronal trans-differentiation. The results indicate an overall good interaction and show that these materials offer a biofriendly environment. A higher concentration of both nanospecies types induced some toxic effects, thus 0.5% GO, MNPs, and GO/MNPs turned out to be the most suitable option for biological testing. Moreover, a successful neuronal differentiation has been shown on these materials, where cells presented a typical neuronal phenotype. This study demonstrates the potential of this scaffold to be further used in tissue engineering applications.

Synthesis and Fabrication of a Betulin-Containing Polyolefin Electrospun Fibrous Mat for Antibacterial Applications

Biocompounds play a significant role in the area of renewable polymers in terms of sustainability, as they can be employed or converted into monomers for polymerization in a manner similar to many petroleum-derived monomers. In this work, betulin, a plant-derived triterpene with antibacterial and antiviral properties, was converted to two kinds of α,ω-diene derivatives with different methylene spacer lengths between the olefin and the ester group via an esterification reaction. Polyolefins were subsequently made by acyclic diene metathesis (ADMET) polymerization of betulin-based α,ω-diene. The polymer consists of rigid betulin and flexible unsaturated aliphatic segments, which was confirmed by NMR spectroscopy and gel permeation chromatography (GPC). The influence of different parameters including temperature, catalysts, and catalyst loading on ADMET polymerization was investigated. These polyolefins with high molar mass (up to 20.0 kg/mol) were obtained in an elevated yield (≥95%). Thermal analysis of these (co)polymers showed excellent thermal stability (up to 360 °C) and tunable glass transition temperatures depending on the nature of betulin and alkene segments. To evaluate the antimicrobial potential of betulin-containing polymers, the fabrication of polyolefin fibrous mats (ca. 400 nm diameter) via the electrospinning technique was successfully achieved. Their morphology and hydrophobicity were studied by scanning electron microscopy (SEM) and water contact angle analyses. The fibrous mats possessed broad-spectrum antibacterial property, providing a feasible strategy to design betulin-based polymeric fibers for many applications in the biomedical field.

Preparation of a sustainable bio-copolymer based on Luffa cylindrica cellulose and poly(ɛ-caprolactone) for bioplastic applications

In this research, a bio-based graft copolymer (LCC-g-PCL) based on the cellulose of Luffa cylindrica (LCC) main chain possessing poly(ɛ-caprolactone) (PCL) pendant groups is synthesized through a grafting from approach via ring-opening polymerization (ROP). For this purpose, LCC, extracted from luffa sponges by combined method, is utilized for ROP of ɛ-caprolactone (ɛ-CL) as a macro-initiator in the presence of stannous octoate as a catalyst. Fourier transform infrared (FT-IR), proton and carbon nuclear magnetic resonance (¹H NMR and ¹³C NMR) spectroscopies are utilized to structurally indicate the success of ROP, while the achieved graft copolymer is analyzed in detail by comparing with LCC and neat PCL in terms of wettability, thermal and degradation behaviors by conducting water contact angle (WCA) measurements, thermogravimetric and differential scanning calorimetry analyses (TGA and DSC) and in vitro both hydrolytic and enzymatic biodegradation tests, respectively. The results of conducted tests show that the incorporation of PCL groups on LCC provide the increasing hydrophobicity. In addition, the degradation behavior of the LCC-g-PCL copolymer is found to be more pronounced under enzymatic medium rather than hydrolytic conditions. It is anticipated from the results that LCC-g-PCL can be a potential eco-friendly material particularly in bioplastic industry.

Fabrication of ciprofloxacin-loaded chitosan/polyethylene oxide/silica nanofibers for wound dressing application: In vitro and in vivo evaluations

Silica plays an effective role in collagen creation; hence, the degradation products of silica-based materials accelerate wound healing. In this regard, chitosan/polyethylene oxide/silica hybrid nanofibers were prepared by the combining the sol-gel method with electrospinning technique to accelerate the wound healing process. Ciprofloxacin, as an antibacterial drug, was then added to the electrospinning mixture. The nanofibers were characterized by SEM, EDX, X-ray mapping, TEM, TGA, FTIR, and XRD analysis. The degradation, swelling ratio, and release of ciprofloxacin were investigated in PBS. The prepared nanofiber could absorb water, maintain its morphological integrity during the degradation process, and gradually release ciprofloxacin. The nanofibers revealed an efficient antibacterial activity against Escherichia coli and Staphylococcus aureus. Cell viability assays showed that the nanofibers had no cytotoxicity against L929 mouse fibroblast and HFFF2 human foreskin fibroblast cell lines. The potential of the chitosan/polyethylene oxide/silica/ciprofloxacin nanofiber for healing full-thickness wound was assessed by applying the scaffold in the dorsal cutaneous wounds of the Balb/C mice. The white blood cell counts of the animals indicated the nanofiber-treated mice compared with the untreated ones had less infection and inflammation. According to the histopathologic data, the prepared nanofiber accelerated and enhanced tissue regeneration by increasing fibroblast cells and angiogenesis as well as decreasing the inflammation phase. The findings suggest that the prepared antibacterial scaffold with drug delivery properties could be an appropriate candidate for many medical and hygienic applications, especially as a bio-compatible and bio-degradable wound dressing.