Keratin Scaffolds Containing Casomorphin Stimulate Macrophage Infiltration and Accelerate Full-Thickness Cutaneous Wound Healing in Diabetic Mice

Impaired wound healing is a major medical challenge, especially in diabetics. Over the centuries, the main goal of tissue engineering and regenerative medicine has been to invent biomaterials that accelerate the wound healing process. In this context, keratin-derived biomaterial is a promising candidate due to its biocompatibility and biodegradability. In this study, we evaluated an insoluble fraction of keratin containing casomorphin as a wound dressing in a full-thickness surgical skin wound model in mice (n = 20) with iatrogenically induced diabetes. Casomorphin, an opioid peptide with analgesic properties, was incorporated into keratin and shown to be slowly released from the dressing. An in vitro study showed that keratin-casomorphin dressing is biocompatible, non-toxic, and supports cell growth. In vivo experiments demonstrated that keratin-casomorphin dressing significantly (p < 0.05) accelerates the whole process of skin wound healing to the its final stage. Wounds covered with keratin-casomorphin dressing underwent reepithelization faster, ending up with a thicker epidermis than control wounds, as confirmed by histopathological and immunohistochemical examinations. This investigated dressing stimulated macrophages infiltration, which favors tissue remodeling and regeneration, unlike in the control wounds in which neutrophils predominated. Additionally, in dressed wounds, the number of microhemorrhages was significantly decreased (p < 0.05) as compared with control wounds. The dressing was naturally incorporated into regenerating tissue during the wound healing process. Applied keratin dressing favored reconstruction of more regular skin structure and assured better cosmetic outcome in terms of scar formation and appearance. Our results have shown that insoluble keratin wound dressing containing casomorphin supports skin wound healing in diabetic mice.     

Development of Antibacterial,Degradable and pH-Responsive Chitosan/Guar Gum/Polyvinyl Alcohol Blended Hydrogels for Wound Dressing

The present research is based on the fabrication preparation of CS/PVA/GG blended hydrogel with nontoxic tetra orthosilicate (TEOS) for sustained paracetamol release. Different TEOS percentages were used because of their nontoxic behavior to study newly designed hydrogels’ crosslinking and physicochemical properties. These hydrogels were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and wetting to determine the functional, surface morphology, hydrophilic, or hydrophobic properties. The swelling analysis in different media, degradation in PBS, and drug release kinetics were conducted to observe their response against corresponding media. The FTIR analysis confirmed the components added and crosslinking between them, and surface morphology confirmed different surface and wetting behavior due to different crosslinking. In various solvents, including water, buffer, and electrolyte solutions, the swelling behaviour of hydrogel was investigated and observed that TEOS amount caused less hydrogel swelling. In acidic pH, hydrogels swell the most, while they swell the least at pH 7 or higher. These hydrogels are pH-sensitive and appropriate for controlled drug release. These hydrogels demonstrated that, as the ionic concentration was increased, swelling decreased due to decreased osmotic pressure in various electrolyte solutions. The antimicrobial analysis revealed that these hydrogels are highly antibacterial against Gram-positive (Staphylococcus aureus and Bacillus cereus) and Gram negative (Pseudomonas aeruginosa and Escherichia coli) bacterial strains. The drug release mechanism was 98% in phosphate buffer saline (PBS) media at pH 7.4 in 140 min. To analyze drug release behaviour, the drug release kinetics was assessed against different mathematical models (such as zero and first order, Higuchi, Baker–Lonsdale, Hixson, and Peppas). It was found that hydrogel (CPG2) follows the Peppas model with the highest value of regression (R² = 0.98509). Hence, from the results, these hydrogels could be a potential biomaterial for wound dressing in biomedical applications.     

Preparation and Characterization of Poly Vinyl Alcohol/Poly Vinyl Pyrrolidone/Clay Based Nanocomposite by Gamma Irradiation

A series of PVA/PVP/clay nanocomposite were prepared by gamma irradiation with different clay contents of (0.15, 0.3, 1, 1.5, 3 and 5 wt%). The gelation content and swelling behavior were investigated. The morphology and structure of PVA/PVP/clay nanocomposite and dispersion of the clay nanoparticles in the polymeric matrix were examined by infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The introduction of clay into polymeric matrix was investigated by X-ray diffraction pattern (XRD) and Transmission electron microscope (TEM). It is observed that, the increase of the clay content causes a decrease in the swelling percent. The thermal stability studies confirmed that the introduction of clay lead to an increase in the thermal stability. The TEM results showed that the clay nanoparticles are interchelated or exfoliated in the polymeric matrix. Some desirable characteristics such as relatively good swelling and excellent barrier capability against microbe penetration suggested that PVA/PVP/clay nanocomposite can be a good candidate as a wound dressing.     

Perspective on “An extended Hückel theory. I. Hydrocarbons”

 The size-consistent self-consistent matrix dressing method has been applied on an open-shell single-configuration reference state. Once the reference state is converged, several low-lying roots can be obtained for the dressed configuration interaction (CI) matrices of appropriate symmetry. The CI matrices were built with a complete-active-space singles and doubles CI method in order to deal properly with multiconfiguration excited states. The vertical ionization and ionization–excitation transitions are obtained from the difference to the closed shell ground-state energy of the neutral molecule. The method has been applied to NH⁺ ₃ and N⁺ ₂ using atomic natural orbital basis sets and state-average adapted molecular orbitals. Two ²A₁ states, very similar and showing great mixing of the (2a _l ⁻¹) and (3a _l ⁻²5a _l ¹) determinants, can be assigned to the broad asymmetric band at 27.6 ± 2 eV in the photoelectron spectrum of NH₃. The possible contribution of a ²Π _g (3σ _g ⁻²1π _g ¹) state to the A shake-up peak of N₂ at 24.6 eV is also discussed. Other states, doublets and quadruplets, are reported for both systems up to 30 eV for NH₃ and 37 eV for N₂. Received: 16 September 1999 / Accepted: 3 February 2000 / Published online: 2 May 2000     

Hydrogel Complex Containing the Antimicrobial Peptide HX-12C Accelerates Healing of Infected Wounds

Bacterial infections of the wound surface can be painful for patients, and traditional dressings do not effectively address this problem. In this study, an antimicrobial wound dressing is prepared using a novel antimicrobial peptide, HX-12C. This hydrogel system is based on the natural biomaterials sodium alginate and gelatin, utilizing calcium carbonate as a source of Ca²⁺, and ionic cross-linking is facilitated by lowering the solution pH. The resulting sodium alginate/gelatin HX-12C-loaded hydrogel (CaAGEAM) has good mechanical and adhesion properties, biocompatibility and in vitro degradability. Its extraordinary antibacterial efficacy (>98%) is verified by an antibacterial experiment. More importantly, in vivo experiments further demonstrate its healing-promotion effect, with a 95% wound healing rate by day 9. Tissue staining demonstrates that the hydrogel containing antimicrobial peptides is effective in suppressing inflammation. The dressing promotes wound healing by stimulating the deposition of skin appendages and collagen. The results of this study suggest that composite hydrogels containing antimicrobial peptides are a promising new type of dressing to promote the healing of infected wounds.     

Fine tuning the assembly and gel behaviors of PEGylated polypeptide conjugates by the copolymerization of l‐alanine and γ‐benzyl‐l‐glutamate N‐carboxyanhydrides

Tuning the secondary structure of polypeptide is an effective strategy to modulate the assembly behaviors of polypeptide‐based copolymers. In this study, ring‐opening polymerization of l ‐alanine (Ala) and γ‐benzyl‐l ‐glutamate (BLG) N‐carboxyanhydrides was adopted using mPEG‐NH₂ as the initiator to prepare mPEG‐poly(l ‐alanine‐co‐γ‐benzyl‐l ‐glutamate) (PEAB) copolymers with various Ala to BLG ratios. ¹H NMR spectra and GPC test confirmed their well‐defined chemical structures. FT‐IR spectra indicated that at the powder state, all copolymers adopted both β‐sheet and α‐helical conformations. With the content of PBLG increased, the crystallization temperature and melting points of PEAB copolymers first rose then fell indicated by DSC curves. The self‐assembly of PEAB copolymers in dilute aqueous solution studied by DLS, TEM and circular dichroism spectra showed that PEAB copolymers self‐assembled into nanostructures with diverse morphologies and sizes due to distinct polypeptide conformations. Rheological analysis indicated that the alteration of the polypeptide composition can effectively modulate the modulus of PEAB assemblies in concentrated solutions. In all, copolymerization of two hydrophobic amino acid N‐carboxyanhydrides into the polypeptide block maybe an effective approach for modulating the assembly properties of PEGylated polypeptide. Besides, nanosilver‐encapsulated PEA or PEAB hydrogel showed promising antibacterial effect against Staphylococcus aureus and Bacillus subtillis. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1512–1523     

Electrospun Lipid Binding Proteins Composite Nanofibers with Antibacterial Properties

Electrospinning is here used for the first time to prepare nanofibers including a host/guest complex in a keratin/poly(ethylene oxide) matrix. The host is a lipid binding protein and the guest is an insoluble bactericidal molecule, irgasan, bound within the protein internal cavity. The obtained nanofibers, characterized by scanning electron microscopy, exhibit excellent antibacterial activity toward Gram positive and negative bacteria, even with a moderate protein/irgasan cargo. Solution NMR studies, employed to provide molecular information on the cargo system, points to a micromolar affinity, compatible with both the electrospinning process and slow guest release. The versatility of the carrier protein, capable of interacting with a variety of druggable hydrophobic molecules, is exploitable for the development of innovative biomedical devices, whose properties can be tuned by the selected guest.

     

Hemostatic and Absorbent PolyHIPE–Kaolin Composites for 3D Printable Wound Dressing Materials

A novel hemostatic and absorbent wound dressing material compatible with 3D printing is developed to address deficiencies in current wound dressing protocol. The design involves an open celled, microporous hydrogel foam via a high internal phase emulsion (HIPE) template with biocompatible components and tunable hemostatic character by kaolin loading, the viscosity and cure kinetics of which are tailored for 3D printing applications. The use of nontoxic mineral oil organic phase results in cytocompatability with human dermal fibroblasts. Kaolin distribution is shown by X‐ray diffraction and elemental dispersive spectroscopy to be exfoliated and dispersed in the hydrogel dressing. In addition to demonstrating high fluid absorption and noncytotoxicity of relevant cell lines, the high internal phase emulsion polymers (polyHIPEs) also match the hemostatic performance of commercial wound dressing materials. Furthermore, the polyHIPEs display the requisite rheological properties for 3D printing that result in the fabrication of a prototype dressing with hierarchical porosity and a large number of controllable form factors.     

Generalized dressing method for the extended two-dimensional Toda lattice hierarchy and its reductions

In this paper, we solve the extended two-dimensional Toda lattice hierarchy (ex2DTLH) by the generalized dressing method developed in Liu-Lin-Jin-Zeng (2009). General Casoratian determinant solutions for this hierarchy are obtained. In particular, explicit solutions of soliton-type are formulated by using the τ-function in the form of exponential functions. The periodic reduction and one-dimensional reduction of ex2DTLH are studied by finding the constraints. Many reduced systems are shown, including the pe...     

Vibrational study on the interactions between yak keratin fibres and glyoxylic acid

Raman and IR spectroscopy were used to investigate the changes induced in yak hair keratin by the straightening treatment based on glyoxylic acid. The amino acidic residues that appeared involved in the reaction with glyoxylic acid were serine and lysine; the involvement of the latter was deduced by the spectroscopic detection of iminic species, resulting from the reaction between the aminic group of lysine and the carbonyl group of glyoxylic acid. The reaction with glyoxylic acid induced conformational rearrangements that mainly involved the fibre bulk rather than the cuticle. Changes in the average tyrosine environment and its hydrogen‐bonding state were detected: at increasing glyoxylic acid incorporation, the tyrosine residues appeared more exposed, probably because of H‐bond interactions with the COOH group. The distribution of the disulfide bridge conformation was also affected, although no cleavage of the S–S bond was detected, in agreement with the shiny and healthy appearance of the fibres. Copyright © 2014 John Wiley & Sons, Ltd.