Engineering of electrospun PCL/Algal polysaccharide/HKUST-1 nanocomposites for potential biomedical applications

Abstract In this study, polycaprolactone (PCL), algal-derived polysaccharides, and HKUST-1 were used to fabricate fibrous nanocomposites via electrospinning as a structural platform for potential biomedical applications. Algal polysaccharides were extracted and purified from Chlorella and Tetraselmis . HKUST-1 was prepared using a hydrothermal method, with Cu(NO₃)₂·3H₂O and Cu(CH₃COO)₂·H₂O as copper precursors. HKUST-1, showed a uniform polyhedral morphology and average particle diameters of approximately 45–50 nm. BET analysis showed mesoporous structures with surface areas of 59.74 and 141.66 m²/g for the nitrate- and acetate-derived MOFs, respectively. PCL solutions with concentrations of 10, 15, 20, and 35% (w/v) were prepared, along with HKUST-1/PCL solutions containing 0.5, 1, 3, 4, and 5 wt% HKUST-1 relative to PCL. To fabricate the nanocomposites, the PCL solutions were initially electrospun to form the fibrous substrate. The three-layer PCL/algal polysaccharide/HKUST-1 nanocomposites were subsequently fabricated by adding the algal polysaccharide of Chlorella and Tetraselmis and HKUST-1 onto the PCL nanofibers. The average fiber diameters ranged from 70–1000 nm. Key fabrication parameters, including solvent type and ratio, solution concentration, and electrospinning conditions, were optimized to obtain uniform and homogeneous nanofibrous structure. The results indicated that the synthesized nanofibers exhibited nanoscale dimensions and a uniform morphology. Incorporating of polysaccharides into the PCL nanofibers increased the surface contact angle from 118° to 130–134°, indicating enhanced surface hydrophobicity. This increase was attributed to the compact molecular structure of the polysaccharides and their limited exposure at the fiber surface during electrospinning. Antibacterial tests revealed that HKUST-1 exhibited antibacterial activity against both E. coli and S. aureus , with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 3.75 and 7.5 mg/mL, respectively. The Tetraselmis -derived polysaccharide exhibited bacteriostatic activity against S. aureus , with an MIC of 25 mg/mL. None of the tested samples exhibited detectable DPPH radical-scavenging activity, which may have been obscured by color interference from the samples at high concentration. This work presents the single-platform nanocomposites combining PCL, Chlorella - and Tetraselmis -derived polysaccharides, and HKUST-1 MOFs.