Antibacterial activity of chitosan–alginate sponges incorporating silver sulfadiazine: Effect of ladder‐loop transition of interpolyelectrolyte complex and ionic crosslinking on the antibiotic release

Abstract

ABSTRACT:Hydrogel membranes prepared from polyelectrolyte complex (PEC) have been used for repair of wounds and controlled antibacterial release. A simple method, based on homogenizing interpolyelectrolyte complex, has been developed to prepare a chitosan-alginate sponge with high stability. The spongelike chitosan-alginate hydrogel can be used as a wound dressing for the sustained release of silver sulfadiazine (AgSD) in a controlled way. In this study, we evaluated the effect of electrolyteic properties of chitosan and alginate on the characteristics of the prepared chitosan-alginate PEC. All types of the spongelike chitosan-alginate hydrogels exhibited superabsorbent properties. However, only the chitosan-alginate hydrogel prepared by the interpolyelectrolyte complex of alginate with low pH of chitosan, and that prepared by the interpolyelectrolyte complex of chitosan with high pH of alginate, can keep their stability after swelling in PBS solution. FTIR analysis suggests that the protonated amino groups on chitosan and the ionized carboxylic groups on alginate should be responsible for the formation of a stable ladder-type of chitosan-alginate PEC. Ionic crosslinking is helpful to increase the stability of the loop-type of chitosan-alginate PEC. The release of AgSD from chitosan-alginate PEC sponges could be controlled by the variation of ladder-loop structural transition of chitosan-alginate PEC and the ionic crosslinking of the chitosan-alginate complex. The antibacterial ability of AgSD-incorporated PEC sponges was examined in agar plate against Pseudomonas aeruginosa and Staphylococcus aureus. The result suggests that the PEC sponges containing antimicrobial agents should effectively suppress bacterial proliferation to protect the wound from bacterial invasion.

Recent Trends in Alginate, Chitosan and Alginate-Chitosan Antimicrobial Systems

“…In the same time with increasing of calcium ions concentration the release rate of antimicrobial compound from systems decreases, because of this, systems containing the lowest concentration of calcium ions (5%), in the conditions of the experiment, showed shortest time in reducing of number of viable bacteria cells to zero [85]. In the alginate-chitosan sponges were encapsulated antimicrobial compounds like: silver sulfadiazine [83,86], gentamicin [84] and ciprofl oxacin [85]; in result, increased the antimicrobial activity against: Staphylococcus aureus [83][84][85][86], Pseudomonas aeruginosa [83,86] and Escherichia coli [85], compared to pristine alginate-chitosan sponges.…”

“…Alginate-chitosan sponge represent a tridimensional porous scaffold, prepared by freeze-drying technique of mixture [83] or consecutively deposited one above the other layers of alginate and chitosan [84][85][86]. Pore sizes range from <100 μm [85,86], 200-400 μm [83] and approximately 500 μm [84], as a function of various factors such as cross-linking time with Ca 2+ ions -with its increasing pore sizes being reduced [83] (Figure 8).…”

“…Pore sizes range from <100 μm [85,86], 200-400 μm [83] and approximately 500 μm [84], as a function of various factors such as cross-linking time with Ca 2+ ions -with its increasing pore sizes being reduced [83] (Figure 8). In the same time with increasing of calcium ions concentration the release rate of antimicrobial compound from systems decreases, because of this, systems containing the lowest concentration of calcium ions (5%), in the conditions of the experiment, showed shortest time in reducing of number of viable bacteria cells to zero [85].…”

“…Due to these properties, alginate-chitosan antimicrobial sponges can be potentially used in wound dressing manufacturing [83,85,86] and in tissue engineering applications [84].…”

Smart polymeric gels: Redefining the limits of biomedical devices

“…For example, the stability of a PEC formed using chitosan and alginate would depend on the ionization of the carboxylate groups of the alginate macromer and of the amino groups of the chitosan macromer, forming the PEC [146][147][148][149][150]. Since alginate-chitosan matrices exhibit pH-dependent swelling, the reversible ionization/deionization of the amino groups in chitosan and the carboxylate groups of alginate would essentially determine the stability of the PEC structure.…”