Preparation and characterization of agar/κ-carrageenan hydrogel wound dressing containing montmorillonite having controlled drug release

In this study, agar/κ-carrageenan and agar/κ-carrageenan/montmorillonite hydrogel wound dressing materials with painkiller and antibacterial property, which supply almost all requirements expected from an ideal wound dressing, were prepared. Montmorillonite clay (MMT) modified with phenyl alanine amino acid was used to improve the some properties of wound dressing materials in hydrogel form. The effects of the concentrations of ammonium persulfate (APS) used as initiator and tri(ethylene glycol) divinyl ether (TEGDE) used as crosslinker, reaction temperature and polysaccharide weight ratio (magar:mκ-karagenan) on the swelling capacity of the hydrogels were investigated and the optimum reaction conditions were determined. The experimental results indicated that the equilibrium swelling capacity of the hydrogel prepared under optimum conditions ([APS]= 5x10-4 M, ([TEGDE]= 5x10-4 M, reaction temperature T= 70 ºC and magar:mκ-carrageenan= 1:4) was 2523%. Swelling degree of hydrogels decreased with increasing MMT concentration within hydrogel matrix. An increase of the clay content within hyrogel matrix from 0% to 5% caused a decrease in the swelling amount of hydrogels from 2458% to 1250% at the end of 300 min. Besides, all hydrogels prepared using different formulations showed non-Fickian swelling behavior. The hydrogels were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), transmission electron microscope (TEM) and differential scanning calorimeter (DSC) techniques. As the content of clay increased from 0% to 5%, the hydrogel decomposition temperature increased from 256.6 ºC to 262.1 ºC. The transparency of the hydrogels was decreased slightly with increasing clay concentration within hydrogel. The opacity values of agar/κ-carrageenan and agar/κ-carrageenan/5% MMT hydrogels were determined as 0.051 and 0.132, respectively. The swelling performances of developed hydrogel wound dressing materials were systematically investigated in various simulated physiological fluids (saline water, synthetic urine, simulated wound fluid and glucose solution). It was observed that swelling degree of the hydrogel in glucose solution (2682%) was much higher than those of saline water (937%), synthetic urine (746%) and simulated wound fluid (563%) at the end of 240 min. The release of anti-inflammatory lidocaine hydrochloride (LDC) and antibacterial chloramphenicol (CLP) drugs from hydrogel systems was investigated by UV-Visible spectrophotometer and HPLC analyses. Drug release studies showed that the amount of lidocaine hydrochloride and chloramphenicol released from synthesized hydrogels can be controlled by the concentration of montmorillonite in the hydrogel composition. Ultimate compressive strength of hydrogels was increased with addition of clay and drug into hydrogel matrix. Ultimate compressive strength of agar/κ-carrageenan and agar/κ-carrageenan/5% MMT hydrogels (with LDC and CLP) was measured as 38.30 kPa and 47.70 kPa, respectively. Antibacterial tests showed that hydrogels containing chloramphenicol have high antibacterial activity against E. coli and S. aureus. According to the results of cytotoxicity experiments, hydrogels are biocompatible with MG-63 cells. The obtained experimental results revealed that synthesized agar/κ-carrageenan and agar/κ-carrageenan/montmorillonite hydrogels containing lidocaine hydrochloride and chloramphenicol have great potential for wound care applications.