Both cold nitrogen radiofrequency plasma and gamma irradiation have been applied to activate and functionalize the polylactic acid (PLA) surface and the subsequent lactoferrin immobilization. Modified films were comparatively characterized with respect to the procedure of activation and also with unmodified sample by water contact angle measurements, mass loss, X-ray photoelectron spectroscopy (XPS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), and chemiluminescence measurements. All modified samples exhibit enhanced surface properties mainly those concerning biocompatibility, antimicrobial, and antioxidant properties, and furthermore, they are biodegradable and environmentally friendly. Lactoferrin deposited layer by covalent coupling using carbodiimide chemistry showed a good stability. It was found that the lactoferrin-modified PLA materials present significantly increased oxidative stability. Gamma-irradiated samples and lactoferrin-functionalized samples show higher antioxidant, antimicrobial, and cell proliferation activity than plasma-activated and lactoferrin-functionalized ones. The multifunctional materials thus obtained could find application as biomaterials or as bioactive packaging films.

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Polysaccharides are important materials in food, pharmaceutical, cosmetic and related biomedical applications. Xanthan gum is a microbial polysaccharide of great commercial significance. Lignin possesses antioxidant, antimicrobial and stabilizer properties. The aim of this study was to investigate by UV-Vis and infrared spectroscopy, wide angle X-ray scattering, differential scanning calorimetry and thermogravimetric studies, the characteristics of biodegradable superabsorbant hydrogels with high swelling rate in aqueous mediums. These were obtained by crosslinking reaction between xanthan gum and different types of lignin (aspen wood lignin, annual fibre crops lignin and lignin epoxy-modified resin) using epichlorhydrine as crosslinking agent. It is expected an increased in thermal stability, hydrophilicity, biocompatibility of hydrogel-films by lignin incorporation. Applications in the food and medical field were also found.

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