Cellulose Acetate Fibers With Infiltrated ZnO Nanocrystals: Activation of Antibacterial Properties Against <i>Acne vulgaris</i> by Oxygen Plasma Treatment

In this work, we developed biodegradable cellulose acetate (CA) fibers infiltrated with ZnO nanocrystals for the Acne vulgaris (AV) treatment. The antibacterial effect (through Zn²⁺ release) was activated upon oxygen plasma treatment. CA fibers (fiber diameter ≈ 2 µm) were produced via centrifugal spinning, followed by ZnO infiltration (up to 8 wt% of Zn content) using Vapor Phase Infiltration (VPI) with varying deposition cycles. As CA fibers are naturally hydrophobic, oxygen plasma treatment was applied to turn them hydrophilic and to improve skin wetting. The combination of these steps is presented for the first time. Plasma treatment introduced oxygen-containing functional groups on the CA surface, significantly improving wettability. Scanning electron microscopy analyses of treated fibers showed no morphological damage. Detailed characterization (using X-ray photoelectron spectroscopy, Raman spectroscopy, energy dispersive X-ray fluorescence, X-ray diffraction, tranmission electron microscopy) focused on fibers with 32 and 128 VPI cycles, revealed that plasma partially oxidized and etched the surface, affecting the ZnO distribution. Plasma-modified fibers, unlike untreated ones, exhibited antibacterial activity against AV-causing bacteria (Cutibacterium acnes and Staphylococcus epidermidis), creating significant inhibition zones (up to 5 mm), demonstrating their potential as promising therapeutic modality. Overall, plasma treatment enabled effective surface functionalization, producing antibacterial fibers with enhanced surface properties suitable for application in AV management.