• Spruce bark extract and tannic acid are potential biocoatings for medical textiles. • Bark extract coatings show superior antiviral activity against CVA9 and HCoV-OC43. • Tannic acid coatings show potency against E. coli , S. aureus , and MRSA bacteria . • Draw-down coating enables the strongest antibacterial and antiviral textile efficacy. • Coating morphology and fiber–polyphenol interactions governed bioactivity. Polyphenol-rich Norway spruce bark extract, a side-stream from the forest industry, is used to create antimicrobial fiber materials for biomedical applications. Lyocell, viscose, and blend non-wovens are coated with the bark extract and commercial tannic acid (TA), which serves as a reference, using three different methods: impregnation, spray coating, and draw-down coating. The antimicrobial efficacy of the coated materials is assessed against a Gram-negative ( Escherichia coli ) and a Gram-positive ( Staphylococcus aureus ) including methicillin-resistant (MRSA) bacteria. Antiviral activity is tested against an enveloped coronavirus (HCoV-OC43) and a non-enveloped Coxsackievirus B3 (CVB3). The bark extract demonstrates strong antimicrobial activity, with the best results achieved on viscose and blended materials using draw-down or impregnation methods. Overall, draw-down coating provides the best performance regarding both antimicrobial and surface properties. Compared to tannic acid, the bark extract is markedly more effective against viruses, an effect attributed to its complex polyphenolic structure. The results indicate that Norway spruce bark extract is a promising bio-based agent for developing antimicrobial materials for healthcare.
Kunnas et al. (2026) studied this question.