Controlled release of bioactive copper (I) acylthiourea complexes through immobilization onto electrospun PCL/lignin...

This study presents the first development of Cu (I) acylthiourea complexes (C1-C5) incorporated polycaprolactone/lignin (PCL/Lig) electrospun nanofiber composites (PCL/Lig@Cu(I)). Electrospinning conditions and mass ratios of PCL and lignin were optimized, followed by the incorporation of varying concentrations of Cu(I) complexes. Structural, morphological, and thermal properties were characterized using SEM, TEM, FT-IR, XRD, TGA and WCA analyses. Mechanical properties, release behavior and antibacterial activity were also assessed. Results confirmed the successful incorporation of Cu-complex into PCL/Lignin nanofiber composites. The PCL/Lig@Cu(I) composite membranes exhibited excellent thermal stability. After incorporating Cu complex into PCL/Lig membranes, the hydrophobicity was found to be enhanced by approximately 5 %. The PCL/Lig@C4 exhibited a stable and continuous release of Cu-complex until the initial 12 h, but after that there was a decrease in the release by 21.27, 26.07 and 24.41 % was observed for the samples PCL/Lig@C4-1%, 2 % and 3 % respectively. To our delight, the PCL/Lig@C4-1% showed a very controlled and steady release of bioactive Cu(I)-complex for a very long period of time (20 days). Overall, our study demonstrates the feasibility of using acylthiourea Cu (I) complexes (C1-C5) immobilized PCL/Lig nanofiber composites for biomedical applications requiring controlled release and antibacterial activity.