This study aimed to develop advanced biomaterial polysaccharide based dressings to manage pain associated with infected chronic leg ulcers in older adults. Composite carrageenan (CARR) and hyaluronic acid (HA) dressings loaded with lidocaine (LID) and AgNPs were formulated as freeze-dried wafers and functionally characterized for porous microstructure (morphology), mechanical strength, moisture handling properties, swelling, adhesion and LID release. Antimicrobial activity of AgNPs was evaluated (turbidity assay) against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus whilst cell viability studies (MTT) was performed on normal adult human primary epidermal keratinocyte cells. The wafers were soft, flexible and elegant in appearance. HA affected the wafer structure by increasing the resistance to compression but still possessed a balance between toughness and flexibility to withstand normal stresses and prevent damage to newly formed skin tissue respectively. Water uptake was influenced by HA, whilst equilibrium water content and LID release were similar for all the formulations, showing controlled release up to 6h. AgNPs loaded CARR/HA wafers were effective in inhibiting the growth of both Gram positive and Gram negative bacteria. MTT assay showed evidence that the AgNPs/LID loaded wafers did not interfere with cell viability and growth. CARR/HA wafers seem to be a promising system to simultaneously deliver LID and AgNPs, directly to infected chronic leg ulcers.
Keywords: Antimicrobial activity; Carrageenan/hyaluronate wafers; Chronic leg ulcers; Lidocaine; Silver nanoparticles; Wound healing.
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