Silver/poly(vinyl alcohol)/graphene hydrogels for wound dressing applications: Understanding the mechanism of silver, antibacterial agent release

Abstract

Long‐term wound healing and chronic wound care represent significant challenges for biomaterials science and engineering with many diverse requirements for the wound dressing properties, as well as antibacterial efficacy and antibacterial agent release to prevent and treat persistent infections. Silver nanoparticles, as a wide‐spectrum antibacterial agent that does not induce bacterial resistance, are very convenient for use as an active component in antibacterial hydrogel wound dressing materials with the controlled release ability. In this work, we aim to perform a comprehensive analysis of silver release from poly(vinyl alcohol)‐based hydrogels with electrochemically synthesized antibacterial silver nanoparticles (AgNPs), aimed for wound dressing applications. Different AgNPs concentrations were loaded in hydrogel matrices using the green electrochemical reduction method, and thus synthesized nanocomposite hydrogels were characterized by different techniques (scanning electron microscopy, Fourier‐transform infrared and Raman spectroscopy, and differential scanning calorimetry), in order to assess their physico‐chemical and thermal properties. Silver release was monitored for 28 days in physiologically‐relevant conditions (phosphate buffered medium, pH 7.4, 37°C). The obtained experimental data were evaluated against several theoretical release models (Korsmeyer‐Peppas, Higuchi, Makoid‐Banakar, Kopcha, and early‐time approximation), which confirmed the predominantly diffusion‐controlled mechanism of release. Finally, AgNP‐loaded hydrogels were assessed for antibacterial activity against Staphylococcus aureus TL and Escherichia coli ATCC25922 bacterial strains, to prove their strong potential for wound dressing applications.

Nanoparticle-Containing Wound Dressing: Antimicrobial and Healing Effects

“…Nešović et al [ 24 ] studied an AgNPs-containing hydrogel with 40–60 nm particles based on polyvinyl alcohol. The germ-kill effect against S. aureus (the TL strain) and E. coli (the ATCC 25922 strain) was observed within 24 h. In that publication the role of the stabilizing agent was played by polyvinyl alcohol, which prevented the agglomeration and the bioactivity loss of AgNPs.…”

“…According to the authors, the silver-containing hydrogel can be applied for wound healing for a prolonged period of time since it releases the silver slowly and maintains the required concentration thereof for 28 days. However, the authors of paper [ 24 ] did not study the mechanical properties of the hydrogel.…”

Emerging treatment strategies in wound care

“…Generally, wound dressings containing graphene‐based nanomaterials are used for several basic reasons including antibacterial activity, increasing mechanical properties, wound moisture retention, biocompatibility and promoting cell proliferation, adhesion, differentiation and growth. 122 , 123 , 124 , 125 Also, graphene‐based nanomaterials alone or in combination with biopolymers have been used in various studies as a drug carrier. 125 , 126 …”

Progress in Antibacterial Hydrogel Dressing

“…Yang et al developed a slow-release antibacterial hydrogel based on branched polyethyleneimine (PEI), stabilized GO-AgNPs, and Pluronic F127 for a more stable and sustained antibacterial effect [ 183 , 184 ]. Kang et al prepared a temperature-sensitive antibacterial hydrogel NIPOM-CG/GM with antibacterial properties based on vinyl carboxymethyl chitosan (CG), silane dispersed graphene (GM), and N-isopro polyacrylamide (NIPAM) [ 185 ].…”