Preparation and evaluation of antibacterial wound dressing based on vancomycin-loaded silk/dialdehyde starch nanoparticles

Recent advances in nanostructured delivery systems for vancomycin

Despite the development of new generations of antibiotics, vancomycin remained as a high-efficacy antibiotic for treating the infections caused by MRSA. Researchers have explored various nanoformulations, aiming to enhance the therapeutic efficacy of vancomycin. Such novel formulations improve the effectiveness of drug cargoes in treating bacterial infections and minimizing the risk of adverse effects. The vast of researches have focuses on enhancing the permeation ability of vancomycin through different biological barriers especially those of gastrointestinal tract. Increasing the drug loading and tuning the drug release from nanocarrier are other important goal for many conducted studies. This study reviews the newest nano-based formulations for vancomycin as a key antibiotic in treating hospitalized bacterial infections.

Prokaryotic Expression, Purification, and Biological Properties of a Novel Bioactive Protein (PFAP-1) from Pinctada fucata

Pinctada fucata meat is the main by-product of the pearl harvesting industry. It is rich in nutrition, containing a lot of protein and peptides, and holds significant value for both medicine and food. In this study, a new active protein was discovered and expressed heterogeneously through bioinformatics analysis. It was then identified using Western blot, molecular weight, and mass spectrometry. The antibacterial activity, hemolysis activity, antioxidant activity, and Angiotensin-Converting Enzyme II (ACE2) inhibitory activity were investigated. An unknown functional protein was screened through the Uniprot protein database, and its primary structure did not resemble existing proteins. It was an α-helical cationic polypeptide we named PFAP-1. The codon-optimized full-length PFAP-1 gene was synthesized and inserted into the prokaryotic expression vector pET-30a. The induced expression conditions were determined with a final isopropyl-β-d-thiogalactoside (IPTG) concentration of 0.2 mM, an induction temperature of 15 °C, and an induction time of 16 h. The recombinant PFAP-1 protein, with low endotoxin and sterility, was successfully prepared. The recombinant PFAP-1 protein exhibited strong antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) in vitro, and the diameter of the inhibition zone was 15.99 ± 0.02 mm. Its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were 37.5 μg/mL and 150 μg/mL, respectively, and its hemolytic activity was low (11.21%) at the bactericidal concentration. The recombinant PFAP-1 protein significantly inhibited the formation of MRSA biofilm and eradicated MRSA biofilm. It also demonstrated potent 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH) scavenging activity with a half-maximal inhibitory concentration (IC50) of 40.83 μg/mL. The IC50 of ACE2 inhibition was 5.66 μg/mL. Molecular docking results revealed that the optimal docking fraction of PFAP-1 protein and ACE2 protein was -267.78 kcal/mol, with a confidence level of 0.913. The stable binding complex was primarily formed through nine groups of hydrogen bonds, three groups of salt bridges, and numerous hydrophobic interactions. In conclusion, recombinant PFAP-1 can serve as a promising active protein in food, cosmetics, or medicine.

Silk fibroin-based dressings with antibacterial and anti-inflammatory properties

Silk fibroin is a fibrillar protein obtained from arthropods such as mulberry and non-mulberry silkworms. Silk fibroin has been used as a dressing in wound treatment for its physical, chemical, mechanical, and biological properties. This systematic review analyzed studies from PubMed, Web of Science, and Scopus databases to identify the molecules preferred for functionalizing silk fibroin-based dressings and to describe their mechanisms of exhibiting anti-inflammatory and antibacterial properties. The analysis of the selected articles allowed us to classify the dressings into different conformations, such as membranes, films, hydrogels, sponges, and bioadhesives. The incorporation of various molecules, including antibiotics, natural products, peptides, nanocomposites, nanoparticles, secondary metabolites, growth factors, and cytokines, has allowed the development of dressings that promote wound healing with antibacterial and immunomodulatory properties. In addition, silk fibroin-based dressings have been established to have the potential to regenerate wounds such as venous ulcers, arterial ulcers, diabetic foot, third-degree burns, and neoplastic ulcers. Evaluation of the efficacy of silk fibroin-based dressings in tissue engineering is an area of great activity that has shown significant advances in recent years.

Recent advances on the preparation conditions, structural characteristics, physicochemical properties, functional properties and potential applications of dialdehyde starch: A review

Starch, a natural storage polysaccharide of plant kingdom, has many industrial applications. However, native starch has some inherent shortages, which can be overcome by structural modification. Dialdehyde starch, one kind of oxidized starch produced by periodate oxidation, has good physical properties and bioactivities with wide applications in different fields. Dialdehyde starch is typically achieved by oxidizing native starch slurry through periodate oxidation under controlled reaction conditions. Several factors including the source of starch, the type of oxidant, the molar ratio of oxidant to starch, reaction temperature, reaction time and solution pH value can influence the synthesis of dialdehyde starch. Dialdehyde starch shows different spectroscopic/chromatographic characters and physicochemical properties from native starch. Moreover, dialdehyde starch exhibits good antioxidant activity, antimicrobial activity and cross-linking property. Based on these functional properties, dialdehyde starch has shown application potentials in food packaging, thermoplastic production, enzyme immobilization, heavy metal ion adsorption, drug delivery, wood adhesion and leather tanning. In this review, the preparation conditions, structural characteristics, physicochemical properties, functional properties and potential applications of dialdehyde starch are summarized for the first time. The future research and development prospects of dialdehyde starch are also discussed.

Fabrication and characterization of bilayer scaffolds made of decellularized dermis/nanofibrous collagen for healing of full-thickness wounds

Skin tissue engineering has progressed from simple wound dressings to biocompatible materials with desired physico-chemical properties that can deliver regenerative biomolecules. This study describes using a novel biomimetic hybrid scaffold of decellularized dermis/collagen fibers that can continuously deliver stromal cell-derived factor-1 alpha (SDF-1α) for skin regeneration. In diabetic rat models, the idea that sustained SDF-1α infusion could increase the recruitment of CXCR4-positive cells at the injury site and improve wound regeneration was investigated. The morphology of the scaffold, its biocompatibility, and the kinetics of SDF-1 release were all assessed. SDF-1α was successfully incorporated into collagen nanofibers, resulting in a 200-h continuous release profile. The microscopic observations exhibited that cells are attached and proliferated on proposed scaffolds. As evaluated by in vivo study and histological examination, fabricated scaffold with SDF-1α release capacity exhibited a remarkably more robust ability to accelerate wound regeneration than the control group. Besides, the SDF-1α-loaded scaffold demonstrated functional effects on the proliferation and recruitment of CD31 and CXCR4-positive cells in the wound bed. Additionally, no adverse effects such as hyperplasia or scarring were found during the treatment period. It may be concluded that the fabricated hybrid scaffold based on natural polymer opens up a new option for topical administration of bioactive molecules. We believe the SDF-1α-loaded hybrid scaffold has promise for skin tissue engineering.