Evaluation of Poly(vinyl alcohol)-Xanthan Gum Hydrogels Loaded with Neomycin Sulfate as Systems for Drug Delivery

Fabrication and characterization of physically crosslinked alginate/chitosan-based hydrogel loaded with neomycin for the treatment of skin infections caused by Staphylococcus aureus

Staphylococcus aureus is a pathogen widely involved in wound infection due to its ability to release several virulence factors that impair the skin healing process, as well as its mechanism of drug resistance. Herein, sodium alginate and chitosan were combined to produce a hydrogel for topical delivery of neomycin to combat S. aureus associated with skin complications. The hydrogel was formulated by combining sodium alginate (50 mg/mL) and chitosan (50 mg/mL) solutions in a ratio of 9:1 (HBase). Neomycin was added to HBase to achieve a concentration of 0.4 mg/mL (HNeo). The incorporation of neomycin into the product was confirmed by scanning electron microscopy, FTIR and TGA analysis. The hydrogels produced are homogeneous, have a high swelling capacity, and show biocompatibility using erythrocytes and fibroblasts as models. The formulations showed physicochemical and pharmacological stability for 60 days at 4 ± 2 °C. HNeo totally inhibited the growth of S. aureus after 4 h. The antimicrobial effects were confirmed using ex vivo (porcine skin) and in vivo (murine) wound infection models. Furthermore, the HNeo-treated mice showed lower severity scores than those treated with HBase. Taken together, the obtained results present a new low-cost bioproduct with promising applications in treating infected wounds.

Design and Synthesis of P(AAm-co-NaAMPS)-Alginate-Xanthan Hydrogels and the Study of Their Mechanical and Rheological Properties in Artificial Vascular Graft Applications

Cardiovascular diseases (CVDs) are the number one cause of mortality among non-communicable diseases worldwide. Expanded polytetrafluoroethylene (ePTFE) is a widely used material for making artificial vascular grafts to treat CVDs; however, its application in small-diameter vascular grafts is limited by the issues of thrombosis formation and intimal hyperplasia. This paper presents a novel approach that integrates a hydrogel layer on the lumen of ePTFE vascular grafts through mechanical interlocking to efficiently facilitate endothelialization and alleviate thrombosis and restenosis problems. This study investigated how various gel synthesis variables, including N,N'-Methylenebisacrylamide (MBAA), sodium alginate, and calcium sulfate (CaSO4), influence the mechanical and rheological properties of P(AAm-co-NaAMPS)-alginate-xanthan hydrogels intended for vascular graft applications. The findings obtained can provide valuable guidance for crafting hydrogels suitable for artificial vascular graft fabrication. The increased sodium alginate content leads to increased equilibrium swelling ratios, greater viscosity in hydrogel precursor solutions, and reduced transparency. Adding more CaSO4 decreases the swelling ratio of a hydrogel system, which offsets the increased swelling ratio caused by alginate. Increased MBAA in the hydrogel system enhances both the shear modulus and Young's modulus while reducing the transparency of the hydrogel system and the pore size of freeze-dried samples. Overall, Hydrogel (6A12M) with 2.58 mg/mL CaSO4 was the optimal candidate for ePTFE-hydrogel vascular graft applications due to its smallest pore size, highest shear storage modulus and Young's modulus, smallest swelling ratio, and a desirable precursor solution viscosity that facilitates fabrication.

Cryostructuring of Polymeric Systems: 67 Properties and Microstructure of Poly(Vinyl Alcohol) Cryogels Formed in the Presence of Phenol or Bis-Phenols Introduced into the Aqueous Polymeric Solutions Prior to Their Freeze-Thaw Processing

Poly(vinyl alcohol) (PVA) physical cryogels that contained the additives of o-, m-, and p-bis-phenols or phenol were prepared, and their physico-chemical characteristics and macroporous morphology and the solute release dynamics were evaluated. These phenolic additives caused changes in the viscosity of initial PVA solutions before their freeze-thaw processing and facilitated the growth in the rigidity of the resultant cryogels, while their heat endurance decreased. The magnitude of the effects depended on the interposition of phenolic hydroxyls in the molecules of the used additives and was stipulated by their H-bonding with PVA OH-groups. Subsequent rinsing of such "primary" cryogels with pure water led to the lowering of their rigidity. The average size of macropores inside these heterophase gels also depended on the additive type. It was found also that the release of phenolic substances from the additive-containing cryogels occurred via virtually a free diffusion mechanism; therefore, drug delivery systems such as PVA cryogels loaded with either pyrocatechol, resorcinol, hydroquinone, or phenol, upon the in vitro agar diffusion tests, exhibited antibacterial activity typical of these phenols. The promising biomedical potential of the studied nanocomposite gel materials is supposed.

Antimicrobial Activity of Artemisia dracunculus Oil-Loaded Agarose/Poly(Vinyl Alcohol) Hydrogel for Bio-Applications

In this study, the potential use of Artemisia dracunculus essential oil in bio-applications was investigated. Firstly, the phytochemicals from Artemisia dracunculus were analyzed by different methods. Secondly, the Artemisia dracunculus essential oil was incorporated into the hydrogel matrix based on poly(vinyl alcohol) (PVA) and agar (A). The structural, morphological, and physical properties of the hydrogel matrix loaded with different amounts of Artemisia dracunculus essential oil were thoroughly investigated. FTIR analysis revealed the successful loading of the essential oil Artemisia dracunculus into the PVA/A hydrogel matrix. The influence of the mechanical properties and antimicrobial activity of the PVA/A hydrogel matrix loaded with different amounts of Artemisia dracunculus was also assessed. The antimicrobial activity of Artemisia dracunculus (EO Artemisia dracunculus) essential oil was tested using the disk diffusion method and the time-kill assay method after entrapment in the PVA/A hydrogel matrices. The results showed that PVA/agar-based hydrogels loaded with EO Artemisia dracunculus exhibited significant antimicrobial activity (log reduction ratio in the range of 85.5111-100%) against nine pathogenic isolates, both Gram-positive (S. aureus, MRSA, E. faecalis, L. monocytogenes) and Gram-negative (E. coli, K. pneumoniae, S. enteritidis, S. typhimurium, and A. salmonicida). The resulted biocompatible polymers proved to have enhanced properties when functionalized with the essential oil of Artemisia dracunculus, offering opportunities and possibilities for novel applications.