Multifunctional gentamicin supplementation of poly(γ-glutamic acid)-based hydrogels for wound dressing application

Rheological Characterization of Genipin-Based Crosslinking Pigment and O-Carboxymethyl Chitosan-Oxidized Hyaluronic Acid In Situ Formulable Hydrogels

The aim of this study was to develop a material capable of rapidly absorbing bodily fluids and forming a resilient, adhesive, viscoelastic hydrogel in situ to prevent post-surgical adhesions. This material was formulated using O-carboxymethyl chitosan (O-CMCS), oxidized hyaluronic acid (OHA), and a crosslinking pigment derived from genipin and glutamic acid (G/GluP). Both crosslinked (O-CMCS/OHA-G/GluP) and non-crosslinked hydrogels (O-CMCS/OHA) were evaluated using a HAAKE™ MARS™ rheometer for their potential as post-surgical barriers. A rheological analysis, including dynamic oscillatory measurements, revealed that the crosslinked hydrogels exhibited significantly higher elastic moduli (G'), indicating superior gel formation and mechanical stability compared to non-crosslinked hydrogels. The G/GluP crosslinker enhanced gel stability by increasing the separation between G' and G″ and achieving a lower loss tangent (tan δ < 1.0), indicating robustness under dynamic physiological conditions. The rapid hydration and gelation properties of the hydrogels underscore their effectiveness as physical barriers. Furthermore, the O-CMCS/OHA-G/GluP hydrogel demonstrated rapid self-healing and efficient application via spraying or spreading, with tissue adherence and viscoelasticity to facilitate movement between tissues and organs, effectively preventing adhesions. Additionally, the hydrogel proved to be both cost effective and scalable, highlighting its potential for clinical applications aimed at preventing post-surgical adhesions.

A Promising Compound for Green Multiresponsive Materials Based on Acyl Carrier Protein

A gel that exhibits intrinsically multiple-responsive behavior was prepared from an oligopeptide and studied. ACP(65-74) is an active decapeptide fragment of acyl carrier protein. We investigated 3% w/v ACP(65-74)-NH2 self-healing physical gels in water, glycerol carbonate (GC), and their mixtures. The morphology was investigated by optical, birefringence, and confocal laser scanning microscopy, circular dichroism, Fourier transform infrared, and fluorescence spectroscopy experiments. We found that all samples possess pH responsiveness with fully reversible sol-to-gel transitions. The rheological properties depend on the temperature and solvent composition. The temperature dependence of the gels in water shows a peculiar behavior that is similar to that of thermoresponsive polymer solutions. The results reveal the presence of several β-sheet structures and amyloid aggregates, offering valuable insights into the fibrillation mechanism of amyloids in different solvent media.

Kick-Starting Wound Healing: A Review of Pro-Healing Drugs

Cutaneous wound healing consists of four stages: hemostasis, inflammation, proliferation/repair, and remodeling. While healthy wounds normally heal in four to six weeks, a variety of underlying medical conditions can impair the progression through the stages of wound healing, resulting in the development of chronic, non-healing wounds. Great progress has been made in developing wound dressings and improving surgical techniques, yet challenges remain in finding effective therapeutics that directly promote healing. This review examines the current understanding of the pro-healing effects of targeted pharmaceuticals, re-purposed drugs, natural products, and cell-based therapies on the various cell types present in normal and chronic wounds. Overall, despite several promising studies, there remains only one therapeutic approved by the United States Food and Drug Administration (FDA), Becaplermin, shown to significantly improve wound closure in the clinic. This highlights the need for new approaches aimed at understanding and targeting the underlying mechanisms impeding wound closure and moving the field from the management of chronic wounds towards resolving wounds.

Fabrication and characterization of chicken feather keratin/polysaccharides blended polymer coated nonwoven dressing materials for wound healing applications

In this research work, three kinds of nonwoven wound dressings were developed from chicken feather keratin (CFK-NW), keratin‑sodium alginate (CFK-SA-NW) and keratin-chitosan (CFK-CS-NW) and characterized using FTIR and SEM. The physical characteristics such as air permeability, thickness and areal density test results revealed the suitability of fabricated materials for wound dressing applications. CFK-SA-NW and CFK-CS-NW indicated a positive antibacterial effect against Gram's positive Staphylococcus aureus and Gram's negative Klebsiella pneumoniae and Escherichia coli bacteria with the zone of inhibition enhanced over >2.0 cm. Moreover, the biomedical potentials of dressing materials has been investigated by cell viability and cytotoxicity tests. Further, the wound healing ability was demonstrated using in vivo model (Albino Wistar rat). The fabricated materials exhibited good support for cell viability and a strong cytocompatibility. Furthermore, the hundred percent wound healing ability of CFK-CS-NW, CFK-SA-NW, CFK-NW and untreated control rats was observed at 15, 17, 21 and 23 days, respectively, Moreover, the wound healing potential of CFK-CS-NW and CFK-SA-NW was found to be better than that of CFK-NW and control group of rats. The outcome of the present study discloses the prospective applications of the developed materials as wound dressing biomaterial.

Biomaterials Made from Coiled-Coil Peptides

The development of biomaterials designed for specific applications is an important objective in personalized medicine. While the breadth and prominence of biomaterials have increased exponentially over the past decades, critical challenges remain to be addressed, particularly in the development of biomaterials that exhibit highly specific functions. These functional properties are often encoded within the molecular structure of the component molecules. Proteins, as a consequence of their structural specificity, represent useful substrates for the construction of functional biomaterials through rational design. This chapter provides an in-depth survey of biomaterials constructed from coiled-coils, one of the best-understood protein structural motifs. We discuss the utility of this structurally diverse and functionally tunable class of proteins for the creation of novel biomaterials. This discussion illustrates the progress that has been made in the development of coiled-coil biomaterials by showcasing studies that bridge the gap between the academic science and potential technological impact.

Dressing with epigallocatechin gallate nanoparticles for wound regeneration

Several reagents have been studied to overcome the problems encountered with antiseptic use, such as moderate cutaneous wound cytotoxicity and skin thinning. We successfully prepared a gelatin/chitosan/epigallocatechin gallate nanoparticle incorporated in a poly(γ-glutamic acid)/gelatin hydrogel, which comprised activated carbon fibers with gentamicin, to fabricate a sandwiched dressing to enhance wound regeneration. The inner layer of activated carbon fibers with gentamicin was designed to prevent bacterial infection, and the outer layer of gelatin/chitosan/epigallocatechin gallate nanoparticles incorporated in a poly(γ-glutamic acid)/gelatin hydrogel was designed to prevent inflammation and facilitate reepithelialization. An in vitro study demonstrated that the dressing effectively inhibited target microorganisms, and scanning electron microscope and confocal laser scanning microscope indicated that the nanoparticles were homogeneously dispersed and migrated into the hydrogel. The in vivo study reported that the sandwiched dressing, comprising the poly(γ-glutamic acid)/gelatin hydrogel, was easy to remove from the wound and facilitated wound tissue regeneration and accelerated healing process.

Active Targeted Nanoparticles for Oral Administration of Gastric Cancer Therapy

Gastric carcinogenesis is a commonly diagnosed type of cancer and has a dismal prognosis because of the rate at which it aggressively spreads and because of the lack of effective therapies to stop its progression. This study evaluated a type of oral drug delivery system of a potential target-activated nanosizer comprising a fucose-conjugated chitosan and polyethylene glycol-conjugated chitosan complex with gelatin containing encapsulated green tea polyphenol extract epigallocatechin-3-gallate, allowing oral administration of the drug through a site-specific release in gastric cancer cells. The results demonstrated that the nanoparticles effectively reduced drug release within gastric acids and that a controlled epigallocatechin-3-gallate release inhibited gastric cancer cell growth, induced cell apoptosis, and reduced vascular endothelial growth factor protein expression. Furthermore, in vivo assay results indicated that the prepared epigallocatechin-3-gallate-loaded fucose-chitosan/polyethylene glycol-chitosan/gelatin nanoparticles significantly affected gastric tumor activity and reduced gastric and liver tissue inflammatory reaction in an orthotopic gastric tumor mouse model.

Trypsin-inspired poly(urethane-urea)s based on poly-lysine oligomer segment

A new kind of biodegradable poly(urethane-urea)s based on poly-lysine oligomer used as the soft segment was synthesized and characterized. In vitro degradation behavior of poly (urethane-urea)s was investigated, and was assessed by (1)H NMR and mass loss. The results indicated that the peptide bonds in poly(urethane-urea)s were effectively cleaved in simulated pancreatic juice containing trypsin, while those in buffer solution without trypsin remained unaffected. The degradability was obviously improved by introducing poly-lysine oligomer into the main chain of poly(urethane-urea)s. The results of cells viability test indicated that the poly (urethane-urea)s showed a good biocompatibility on endothelial cells. The thermostability and hydrophilicity of poly(urethane-urea)s increased with increase in poly-lysine oligomer content.

Berberine-loaded targeted nanoparticles as specific Helicobacter pylori eradication therapy: in vitro and in vivo study

AIM

The aim of this work was to develop fucose-conjugated nanoparticles and control the release of berberine, and demonstrate that these particles come into contact with Helicobacter pylori and enhance the suppressive effect of berberine on H. pylori growth.

MATERIALS & METHODS

Fucose-chitosan/heparin nanoparticle-encapsulated berberine was prepared and delivery efficiency was monitored by confocal laser scanning microscopy. Anti-H. pylori activities were investigated by determining the calculated bacterial colonies and immunohistochemistry staining analysis.

RESULTS

Analysis of a simulated gastrointestinal medium indicated that the proposed drug carrier effectively controls the release of berberine, which interacts specifically at the site of H. pylori infection, and significantly increases berberine's suppressive effect on H. pylori growth. In an in vivo study, the berberine-loaded fucose-conjugated nanoparticles exhibited an H. pylori clearance effect.

CONCLUSION

These findings indicate that berberine-loaded fucose-conjugated nanoparticles exert an H. pylori clearance effect and effectively reduce gastric inflammation in an H. pylori-infected animal study.

Evaluation of various silver-containing dressing on infected excision wound healing study

Silver-containing dressings have been widely used for controlling wound infection. However, the relationship between different concentrations of silver in dressings and their antimicrobial activities and wound-healing efficacies remains unclear. In the present study, we (in cooperation with Bio-medical Carbon Technology) investigated various silver-containing activated carbon fibers to understand the effects of different silver concentrations on the efficacies of a silver containing dressing. Our results indicated that various silver-containing activated carbon fibers exhibited good antibacterial effects and biocompatibility in terms of cell viability and that silver concentration showed a minor influence on cell growth. The infected excision wound model indicated that compared to silver-containing activated carbon fiber and other commercial silver-containing dressings assisted wound healing by promoting granulation and collagen deposition. Meanwhile, the silver ion can only be restrained in epidermis by intact skin. During application on the wound area, a temporary increase of serum silver can be detected, but this elevated serum silver level decreased to a subtle level after the removal of silver-containing activated carbon fiber.

Tubular scaffolds of gelatin and poly(ε-caprolactone)-block-poly(γ-glutamic acid) blending hydrogel for the proliferation of the primary intestinal smooth muscle cells of rats

The proper regeneration of intestinal muscle for functional peristalsis is the most challenging aspect of current small intestine tissue engineering. This study aimed to fabricate a hydrogel scaffold for the proliferation of intestinal smooth muscle cells (ISMCs). Tubular porous scaffolds of 10-20 wt% gelatin and 0.05-0.1 wt% poly(ε-caprolactone)-block-poly(γ-glutamic acid) blending hydrogel were cross-linked by carbodiimide and succinimide in an annular space of a glass mold. The scaffolds with higher gelatin contents degraded slower in the phosphate buffer solution. In rheological measurements, the hydrated scaffolds were elastic (all tangent delta <0.45); they responded differentially to frequency, indicating a complete viscoelastic property that is beneficial for soft tissue regeneration. Isolated rat ISMCs, with the characteristic biomarkers α-SMA, calponin and myh11, were loaded into the scaffolds by using either static or centrifugal methods. The average cell density inside the scaffolds increased in a time-dependent manner in most scaffolds of both seeding groups, although at early time points (seven days) the centrifugal seeding method trapped cells more efficiently and yielded a higher cell density than the static seeding method. The static seeding method increased the cell density from 7.5-fold to 16.3-fold after 28 days, whereas the centrifugal procedure produced a maximum increase of only 2.4-fold in the same period. In vitro degradation data showed that 50-80% of the scaffold was degraded by the 14th day. However, the self-secreted extracellular matrix maintained the integrity of the scaffolds for cell proliferation and spreading for up to 28 days. Confocal microscopic images revealed cell-cell contacts with the formation of a 3D network, demonstrating that the fabricated scaffolds were highly biocompatible. Therefore, these polymeric biomaterials hold great promise for in vivo applications of intestinal tissue engineering.

Responsive poly (γ-glutamic acid) fibres for biomedical applications

A novel responsive system using a protein-based biopolymer was designed to undergo structural, geometric, and chemical changes upon temperature change or solvent interaction. Poly(γ-glutamic acid) (γ-PGA) is an attractive candidate for various biomedical applications as it is naturally produced, biocompatible and enzymatically degradable. The responsive material was fabricated using an electrospun modified γ-PGA to create a sub-micron fibrous mat. By modulating the environment responsive behaviour in a controlled manner, exciting applications such as wound dressing, compression materials and self-tightening knots are envisaged.

Development of fibroblast culture in three-dimensional activated carbon fiber-based scaffold for wound healing

This work developed a novel bi-layer wound dressing composed of 3D activated carbon fibers that allows facilitates fibroblast cell growth and migration to a wound site for tissue reconstruction, and the gentamicin is incorporated into a poly(γ-glutamic acid)/gelatin membrane to prevent bacterial infection. In an in vitro, field emission scanning electron microscopy shows that rat skin fibroblasts appeared and spread on the surface of activated carbon fibers, and penetrated the interior and exterior of the 3D activated carbon fiber construct to a depth of roughly 200 μm. An in vivo analysis shows that fibroblast cells containing the proposed 3D scaffold had the potential of a biologically functionalized dressing to accelerate wound closure. Additionally, fibroblasts migrated to the wound site in a bi-layer wound dressing containing fibroblasts, enhancing fibronectin and type I collagen expression, resulting in faster skin regeneration than that achieved with a Tegaderm™ hydrocolloid dressing or gauze.