Screening of plant essential oils identifies Piper nigrum and Juniperus rigida for incorporation into carboxymethyl cellulose-polyvinyl alcohol hydrogel films as potential multifunctional wound dressings

Antimicrobial resistance and biofilm-associated chronic wounds highlight the need for natural wound-care materials with broad antimicrobial, antibiofilm, and antioxidant properties. In this study, eight plant essential oils (EOs) were initially screened for antimicrobial activity, leading to the selection of Piper nigrum and Juniperus rigida for incorporation into carboxymethyl cellulose-polyvinyl alcohol hydrogel films (EO-CMC-PVA), potentially multifunctional, infection-controlling wound dressings. Antimicrobial activity of eight EOs against Staphylococcus aureus , Escherichia coli , and Candida albicans was assessed. P. nigrum and J. rigida were further evaluated for antibiofilm and antioxidant effects. EO–CMC–PVA films were fabricated, characterized, and evaluated for functional and release properties. Among the EOs screened, P. nigrum and J. rigida exhibited the strongest antimicrobial activity. P. nigrum showed significantly lower MICs (0.125–0.25% v/v) than J. rigida (0.25–0.5% v/v; p < 0.05) and achieved ≥ 3 log10 CFU/mL reductions at 1 × MIC. P. nigrum displayed lower MBIC₅₀ (0.25% vs 0.5%) and MBEC (1.0% vs 2.0%; p < 0.05). EO-CMC-PVA films demonstrated bactericidal and fungicidal activity in time-kill assays and significantly reduced biofilm formation. Incorporation into CMC-PVA films retained the activity of EOs, producing inhibition zones of 18.2 ± 0.8 mm ( S. aureus ) and 16.1 ± 0.7 mm ( C. albicans ). The EO-CMC-PVA films were transparent with a mild yellow tint (ΔE < 6), hydrophilic (contact angle < 50°), and exhibited high swelling (~ 180 ± 8%), making them suitable for exudate absorption. Water vapour permeability ranged from 1.8 × 10⁻⁹ to 2.7 × 10⁻⁹ g mm⁻ 1 m⁻ 2 day⁻ 1 kPa⁻ 1 . FTIR confirmed EO incorporation through new C = O and C–O bands, while SEM revealed increased surface roughness and microporosity, especially at 1% EO concentration. DPPH assays demonstrated higher antioxidant activity for P. nigrum films (65 ± 3%) compared to J. rigida (50 ± 4%), and > 85% Vero cell viability confirmed biocompatibility. Both P. nigrum and J. rigida EOs exhibited strong antimicrobial, antibiofilm, and antioxidant activities, with P. nigrum showing superior efficacy ( p < 0.05). Incorporation of EOs into CMC-PVA hydrogel films preserved bioactivity and favourable physicochemical properties, supporting their potential as bioactive wound-dressing materials for infected and oxidative-stress-compromised wounds.