Composite Hydrogels with Embedded Silver Nanoparticles and Ibuprofen as Wound Dressing

Abstract

The wound healing process is often slowed down as a result of complications from bacterial infections and inflammatory reactions. Therefore, it is necessary to develop dressings with fast antibacterial and anti-inflammatory activity that shorten the wound healing period by promoting cell migration and proliferation. Chitosan (CS)-based hydrogels have been widely studied for their antibacterial and wound healing capabilities. Herein, we developed a composite hydrogel based on CS and PVA embedding silver nanoparticles (AgNPs) with antibacterial properties and ibuprofen (Ib) as an anti-inflammatory agent. The hydrogel prepared by double physical cross-linking, with oxalic acid and by freeze–thawing, loaded with 0.225 wt.% AgNPs and 0.264 wt.% Ib, displayed good mechanical properties (compressive modulus = 132 kPa), a high swelling degree and sustained drug delivery (in simulated skin conditions). Moreover, the hydrogel showed strong antibacterial activity against S. aureus and K. pneumoniae due to the embedded AgNPs. In vivo, this hydrogel accelerated the wound regeneration process through the enhanced expression of TNF alpha IP8, by activating downstream cascades and supporting the healing process of inflammation; Cox2, which enhances the migration and proliferation of cells involved in re-epithelialization and angiogenesis; MHCII, which promotes immune cooperation between local cells, eliminating dead tissue and controlling infection; the intense expression of Col I as a major marker in the tissue granulation process; and αSMA, which marks the presence of myofibroblasts involved in wound closure and indicates ongoing re-epithelialization. The results reveal the potential healing effect of CS/PVA/AgNPs/Ib hydrogels and suggest their potential use as wound dressings.

Topical Meloxicam Hydroxypropyl Guar Hydrogels Based on Low-Substituted Hydroxypropyl Cellulose Solid Dispersions

“…Analogous highly porous formations have been previously reported for different freeze-dried topical hydrogels. These structures are characteristic of SEM studies of hydrogels formed by the polymer relaxation in an aqueous medium after a freeze-drying process [ 16 , 40 ]. Scanning electron micrographs of meloxicam HMX − RM hydrogel ( Figure 6 ) exhibited a characteristic morphology of crystalline aggregates with sizes of around 10–20 µm and a smooth surface [ 41 ].…”

“…The solid dispersion hydrogel HSD − MX:LHPC (1:2.5) showed the largest changes in the structure of the freeze-dried hydrogel. The high hydration capacity of the solid dispersion presented a decrease in the pore size of the hydrogels [ 4 , 16 ]. HSD − MX: LHPC: (1:2.5) displayed an absence of MX’s crystal groups, and it is only observed the presence of small crystals (1–5 µm) within the LHPC fibers ( Figure 6 ).…”

“…The absence of other MX bands was attributed to overlapping bands of the HPG hydrogel. In addition, the lack of changes in the HMX − RM and HPM − MX:LHPC (1:2.5) FTIR spectra indicated that there was no interaction between the MX and HPG polymer [ 16 , 17 ]. Finally, HSD − MX:LPC (1:2.5) hydrogel showed a peak at 3289 cm −1 attributed to the overlap of the N–H band within the –OH band for the HPG hydrogel.…”

“…To study drug release under conditions similar to those observed on the skin surface, the different SD hydrogel formulations are evaluated with water or acetate buffer pH 5.5. These media have been commonly used in dissolution studies with different hydrogels for topical administration [ 14 , 16 ]. Furthermore, the simulated medium at pH 5.5 proved to be suitable for showing significant differences in solid dispersions of poorly soluble drugs [ 16 ].…”

“…These media have been commonly used in dissolution studies with different hydrogels for topical administration [ 14 , 16 ]. Furthermore, the simulated medium at pH 5.5 proved to be suitable for showing significant differences in solid dispersions of poorly soluble drugs [ 16 ]. Finally, the different kinetic studies of topical hydrogels are adequate to relate the dissolution profiles with the degree of drug/polymer interaction observed for the different SDs [ 2 , 17 , 18 ].…”