Poly(caprolactone)/Lignin-based 3D-printed Dressings Loaded with a Novel Combination of Bioactive Agents for Wound-healing Applications

Curcumin (CUR) has been shown to possess significant anti-inflammatory properties and significant wound healing potential. Additionally, lignin (LIG) is a renewable biomacromolecule with well-known antioxidant and antimicrobial properties, which makes this biomacromolecule a good candidate to be included in medical materials, such as wound dressings. Although many of the wound dressings used at present have interesting features, some are limited in terms of antibacterial properties. To address these limitations, in the present work, both CUR and LIG were combined with poly(caprolactone) (PCL), a biocompatible polymer, to obtain dressings with antioxidant and antimicrobial properties for wound healing treatment. Moreover, D-Panthenol (DPA) was included in the composite materials formulation due to its skin regenerative ability by enhancing epidermal differentiation. Semi-solid extrusion (SSE) 3D printing was used to manufacture wound dressings without the use of any solvents. 3D-printed dressings provided a sustained DPA and CUR release for periods of up to 4 and 35 days, respectively. A DPPH (2,2-diphenyl-1-picrylhydrozyl) assay was performed confirming that the presence of LIG and CUR provided antioxidant properties to the 3D-printed dressings. Additionally, these 3D-printed materials showed a marked resistance to adherence of Staphylococcus aureus when compared to the PCL control 3D-printed samples, resulting in substantial reductions of up to 89.9% and 98.9% after incubation periods of 4 h and 24 h respectively. Although, all of the 3D-printed materials were able to provide a supportive environment for cellular attachment, viability and growth, the combination of both bioactive compounds CUR and DPA exhibited the most significant values for cell viability and proliferation. In vivo wound healing study performed in Wistar rats showed that dressings containing these novel two compounds CUR and DPA exhibited marked improvement at any stage of the treatment process.