Injectable Human Hair Keratin–Fibrinogen Hydrogels for Engineering 3D Microenvironments to Accelerate Oral Tissue Regeneration

Traumatic injury of the oral cavity is atypical and often accompanied by uncontrolled bleeding and inflammation. Injectable hydrogels have been considered to be promising candidates for the treatment of oral injuries because of their simple formulation, minimally invasive application technique, and site-specific delivery. Fibrinogen-based hydrogels have been widely explored as effective materials for wound healing in tissue engineering due to their uniqueness. Recently, an injectable foam has taken the spotlight. However, the fibrin component of this biomaterial is relatively stiff. To address these challenges, we created keratin-conjugated fibrinogen (KRT-FIB). This study aimed to develop a novel keratin biomaterial and assess cell–biomaterial interactions. Consequently, a novel injectable KRT-FIB hydrogel was optimized through rheological measurements, and its injection performance, swelling behavior, and surface morphology were investigated. We observed an excellent cell viability, proliferation, and migration/cell–cell interaction, indicating that the novel KRT-FIB-injectable hydrogel is a promising platform for oral tissue regeneration with a high clinical applicability.

Low Concentration and High Transparency Keratin Hydrogel Fabricated via Cryoablation

Keratins are highly attractive for medical applications due to their inherent self-assemblies characteristics and biocompatibility. However, nearly all researches have focused on the properties of hybrid hydrogels which was prepared from human hair keratin with other materials, and the preparation methods and properties of pure keratin hydrogels are rarely studied. Thus, we extracted keratins from rabbit hair, and a low concentration and high purity RHK hydrogel was then prepared by a simple freeze–thaw cycle and used to study gelation and the optical properties. The results indicated that RHK keratin hydrogel is a reversible thixotropic system and elastic modulus the storage modulus (G′) substantially improves with freeze–thaw cycles. The systematic assessments including microstructural observation, porosity, and the secondary structure confirmed that the structure and properties of keratin hydrogels can be changed by controlling freeze–thaw cycles. Meanwhile, it is found that RHK hydrogel had high optical transmittance, and still maintained its fluorescent properties, which would be useful to observe the wound healing and locate the drug delivery process.

Human Hair Keratin Composite Scaffold: Characterisation and Biocompatibility Study on NIH 3T3 Fibroblast Cells

The aim of this study was to transform human hair keratin waste into a scaffold for soft tissue engineering to heal wounds. The keratin was extracted using the Shindai method. Keratin and polyvinyl alcohol (PVA) was cross-linked with alginate dialdehyde and converted into a scaffold by the freeze-drying method using gentamycin sulphate (GS) as a model drug. The scaffold was subjected to Fourier transform infrared spectra (FTIR), swelling index, porosity, water absorption, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), drug release, and cell viability (MTT) analysis. The scaffold was tested for keratinocyte growth using the murine fibroblast cell line (NIH 3T3 cells). The outcome from the keratin had a molecular weight band between 52–38 kDa in SDS-PAGE (Sodium dodecylsulfate-Polyacrylamide gel electrophoresis). A porous scaffold was capable of water absorption (73.64 ± 14.29%), swelling ability (68.93 ± 1.33%), and the release of GS shown as 97.45 ± 4.57 and 93.86 ± 5.22 of 1:4 and 1:3 scaffolds at 16 h. The physicochemical evaluation revealed that the prepared scaffold exhibits the proper structural integrity: partially crystalline with a strong thermal property. The scaffold demonstrated better cell viability against the murine fibroblast cell line (NIH 3T3 cells). In conclusion, we found that the prepared composite scaffold (1:4) can be used for wound healing applications.

Investigating the molecular mechanisms and mechanical properties of epithelial keratin and trichocyte keratin using multiscale modelling

Establishing a deeper understanding of the molecular mechanisms and mechanical properties of materials can help improve engineering processes and also contribute to establishing a better understanding of diseases and how they can be treated. A better understanding of the exact structures and mechanisms of a material and how they affect a material's properties, can lead to the development of new, novel materials that can respond to societal needs. Assistant Professor Chia-Ching Chou, Institute of Applied Mechanics, National Taiwan University, Taiwan, is working to better understand the intricacies of materials by taking inspiration from nature, with a particular focus on two types of keratin. Chou and her team are using molecular modelling to investigate the molecular mechanisms and mechanical properties of epithelial keratin and trichocyte keratin. Trichocyte keratin, otherwise known as hair keratin, is durable and has had a number of applications in engineering for many years, while epithelial keratin, which is also known as skin keratin, cannot sustain the same load as hair keratin, but has a greater ability to be stretched, and is therefore of interest to the team. Chou and the team are investigating how the molecular compositions of trichocyte keratin and epithelial keratin affect the mechanical properties. To do this, the researchers are performing molecular dynamics simulation using atomistic and multiscale computational modelling, which allows them to explore the composition, structure and behaviour of keratin at the molecular level. Ultimately, the researchers want to determine how sequence and chemical bonding affect the microscopic, mesoscopic and macroscopic level properties of materials.