The main objective of this study was to obtain chitosan functionalized viscose fabric with improved antibacterial properties and washing durability. In this regard carboxyl and aldehyde groups, as binding points for irreversible chitosan attachment into/onto viscose fabric, were introduced by two different pretreatments: 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) oxidation and coating with TEMPO oxidized cellulose nanofibrils (TOCN). The Fourier transform infrared spectroscopy, elemental analysis, zeta potential measurements, scanning electron microscopy, breaking strength and antibacterial testing were used to evaluate the influence of these pretreatments on chitosan binding, but also on chemical, electrokinetic, morphological, mechanical and antibacterial properties of pretreated and chitosan functionalized viscose fabrics. Washing durability of chitosan functionalized viscose was monitored through changes in the chitosan content, electrokinetic and antibacterial properties after multiple washing. TOCN coating improves mechanical properties of fabric, while TEMPO oxidation deteriorates them. The results show that both pretreatments improve chitosan adsorption and thus antibacterial properties, which are highly durable to washing. After five washings, the chitosan functionalized pretreated viscose fabrics preserve their antibacterial activity against Staphylococcus aureus, while antibacterial activity against Escherichia coli was lost. TOCN coated and chitosan functionalized viscose fabric is a high value-added product with simultaneously improved antibacterial and mechanical properties, which may find application as medical textiles.

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Nanostructured and bio-active polysaccharide-based thin films were manufactured by means of subsequent spin-coated deposition of a regenerated cellulose (RC) layer and a 2,2,6,6-Tetramethylpiperidine-1-oxyl radical (TEMPO) oxidised cellulose nanofibril (TOCN) layer. The bio-activity of the bilayer was achieved by addition of chitosan (CS). The chitosan was either mixed with the TOCN (TOCN+CS) and deposited on the RC layer by spin-coating, or deposited on the RC and TOCN bilayer by pumping its aqueous solution with various pH over the surface of the bilayer. The water content of the thin films and the CS interactions with the bilayer during deposition were studied in situ by means of a quartz crystal microbalance with dissipation (QCM-D). The pH dependent charging behaviour of the TOCN, TOCN+CS and CS dispersions was evaluated by pH-potentiometric titrations. The surface morphology of the thin films was characterised by atomic force microscopy (AFM). The bio-activity of the thin films was evaluated by studying their protein-repellent properties in situ with a continuous flow of bovine serum albumin (BSA) by means of QCM-D and by evaluating their antibacterial properties in vitro against Staphylococcus aureus and Escherichia coli. These polysaccharide-based thin films are high value-added products because of their multifunctionality, high water absorbance capacity, protein-repellence and antimicrobial activity, and have the potential for medical application as a wound dressing material.

This research proposed two pretreatments of viscose fabrics: oxidation with 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) and coating with TEMPO-oxidized cellulose nanofibrils (TOCN), to introduce functional groups (COOH and CHO) suitable for irreversible binding of chitosan nanoparticles without and with embedded zinc (NCS and NCS + Zn, respectively) and consequently achieving washing durable antibacterial properties of the chitosan nanoparticles functionalized fabrics. The characterizations of pretreated and chitosan nanoparticles functionalized fabrics were performed by FTIR and XPS spectroscopy, elemental analysis, inductively coupled plasma optical emission spectrometry, zeta potential measurements, scanning electron microscopy, determination of COOH and CHO groups content, and antimicrobial activity under dynamic contact conditions. Influence of pretreatments on NCS and NCS + Zn adsorption, chemical, electrokinetic, and antibacterial properties as well as morphology, and washing durability of NCS and NCS + Zn functionalized fabrics were studied and compared. Washing durability was evaluated through changes in the chitosan and zinc content, zeta potential, and antibacterial activity after 1, 3, and 5 washing cycles. Pretreatments improved washing durability of antibacterial properties of chitosan nanoparticles functionalized fabrics. The NCS and NCS + Zn functionalized pretreated fabrics preserved antibacterial activity against S. aureus after five washing cycles, while antibacterial activity against E. coli was preserved only after one washing cycle in the case NCS + Zn functionalized pretreated viscose fabrics.