Dual Cross-Linked Chitosan/PVA Hydrogels Containing Silver Nanoparticles with Antimicrobial Properties

Abstract

Stable chitosan/PVA-based hydrogels were obtained by combining covalent and physical cross-linking methods. As covalent cross-linkers, epoxy agents with different chain lengths were used, while freeze–thaw cycles were applied for additional physical cross-linking. The chemical structure of the hydrogel was examined by FTIR spectroscopy whereas the morphology was analyzed by SEM, showing well-defined pores with dimensions of around 50 μm in diameter. It was proved that gel fraction and the network morphology were deeply influenced by the synthesis conditions. Chitosan/PVA hydrogel showed a relative high swelling rate, reaching equilibrium in the first hour. The values obtained for the elastic modulus were relatively low (3–30 kPa); as a result, these hydrogels are soft and very flexible, and are ideal candidates for medical applications as wound or oral dressings. In addition, the natural antimicrobial activity of chitosan was enhanced by in situ generation of silver nanoparticles (AgNPs) under UV irradiation. The total amount of Ag from hydrogel was determined by elemental analyses and its crystalline state was confirmed by XRD. The CS/PVA hydrogels entrapped with AgNPs exhibited high inhibitory activity against S. aureus and K. pneumonia. The vitality tests confirmed the lack of cytotoxicity of CS/PVA hydrogels without and with AgNPs.

Chitosan/Pluronic F127 Thermosensitive Hydrogel as an Injectable Dexamethasone Delivery Carrier

“…Figure 2 II(a) shows the spectrum of chitosan with its characteristic signals: a broad absorption pick between 3500 and 3200 cm −1 attributed to the stretching vibration of O–H and N–H as well as another more discrete signal around 2900 cm −1 associated with the stretching vibration of CH. On the other hand, signals are observed at 1653 cm −1 attributed to the stretching vibration of C═O in the amide I group and at 1560 cm −1 attributed to the N–H bending and the C–N stretching vibrations in the amide II group [ 43 , 44 , 45 ]. The spectrum of Figure 2 II(b) corresponding to pluronic shows the signals associated with the functional groups present in this polymer.…”

Polysaccharide-Based Hydrogels for Wound Dressing: Design Considerations and Clinical Applications

“…The results also showed the ratio of the formulation composition influences the water retention and swelling properties ( Lou et al, 2011 ). In addition, other researchers have attempted to obtain double-networked hydrogels for more demanding wound healing by combining physical and chemical cross-linking of the hydrogels (T. Chen et al, 2018 ; Suflet et al, 2021 ). For instance, a sodium alginate-based hydrogel was developed with efficient self-healing ability (80% mechanical recovery in 6 h), high tensile strength (0.109 MPa), and ultra stretchability, which are considered as desirable properties and superior to previously reported tough and self-healing hydrogels for wound dressing applications (T. Chen et al, 2018 ).…”

“…Suflet et al synthesized stable chitosan-based hydrogels by combining covalent and physical cross-linking methods, which showed a relative high swelling rate and low elastic modulus (3–30 kPa). As a result, the hydrogels are soft and flexible, which are ideal candidates for oral dressings ( Suflet et al, 2021 ).…”

Current and Future Prospective of Injectable Hydrogels—Design Challenges and Limitations

“…These various hydrogel systems have wide applications in biomedical sciences through various means. They each have advantages and disadvantages according to their fabrication and structural design—for instance, uncontrolled biodegradation and batch-to-batch variations associated with natural polymeric material make it difficult to control their mechanical strength and properties, which in comparison with synthetic polymers usually have a well-defined 3D structure and robustness [ 16 , 17 , 18 , 19 , 20 ].…”

“…Different techniques have been utilized to generate 3D hydrogel structures either from natural or synthetic sources via chemical crosslinking (click chemistry, photo polymerization, Schiff’s base, enzyme-catalyzed or thiol-based Michael reactions) or physical crosslinking (induced through temperature, pH, ionic interactions, stereo complexation or guest–host inclusion reactions) [ 17 , 18 , 19 , 20 ]. Hydrogels generated through these methods have the capabilities of the encapsulation and release of drugs and biomolecules (DNA, gene, RNA and proteins) for various therapeutic purposes [ 21 ].…”