ABSTRACT

Microenvironment of majority chronic wounds exhibits pH in the range of 7.5 to 8.5, leading to poor healing prognosis. The elevated pH adds to dysregulation of healing cascade by creating hypoxia, elevating matrix metalloproteinase (MMP) activity and chances of infection. The current work focuses on fabrication of pH regulating agar-citric acid bi-layer dressing for effective management of chronic wounds. The desired pH in the range of 6 to 7 was achieved by unidirectional release of citric acid through bi-layer arrangement of agar-citric acid films in contact with wound simulating fluid of pH ~ 8.5. At lower pH (6.5), both MMP 9 and MMP 2 degraded lesser gelatin (0.11 µg/mg ± 0.003 µg/mg) as compared to higher pH (8.5) value (0.18 µg/mg ± 0.004 µg/mg). The dressing also exhibited bacteriostatic effect on Staphylococcus aureus and Pseudomonas aeruginosa bacteria cultured in-vitro. The bilayer dressing exhibited an average tensile strength of 27 MPa ± 2.5 MPa along with 52 ± 5% elongation at break. The percentage swelling and water vapor transmission rate of dressing was 112% ± 20% and 2156 g/m²/day ± 128 g/m²/day respectively.

摘要

大多数慢性伤口的微环境pH值在7.5到8.5之间，导致愈合预后不良。升高的 pH 值通过产生缺氧、提高基质金属蛋白酶 (MMP) 活性和感染机会来增加愈合级联的失调。目前的工作重点是制造 pH 调节琼脂-柠檬酸双层敷料，以有效管理慢性伤口。通过与 pH ~ 8.5 的伤口模拟流体接触的琼脂-柠檬酸薄膜的双层排列，柠檬酸的单向释放可实现 6 至 7 范围内的所需 pH 值。在较低的 pH (6.5) 下，与较高的 pH (8.5) 值 (0.18 µg/mg ± 0.004 µg/mg) 相比，MMP 9 和 MMP 2 降解较少的明胶 (0.11 µg/mg ± 0.003 µg/mg)。该敷料还对体外培养的金黄色葡萄球菌和铜绿假单胞菌具有抑菌作用。双层敷料的平均拉伸强度为 27 MPa ± 2.5 MPa，断裂伸长率为 52 ± 5%。敷料溶胀百分率和水蒸气透过率分别为112%±20%和2156 g/m² /天±128 g/m ² /天。