Alginate Biofunctional Films Modified with Melanin from Watermelon Seeds and Zinc Oxide/Silver Nanoparticles

Abstract

Bioactive films find more and more applications in various industries, including packaging and biomedicine. This work describes the preparation, characterization and physicochemical, antioxidant and antimicrobial properties of alginate films modified with melanin from watermelon (Citrullus lanatus) seeds at concentrations of 0.10%, 0.25% and 0.50% w/w and with silver and zinc oxide nanoparticles (10 mM film casting solutions for both metal nanoparticles). Melanin served as the active ingredient of the film and as a nanoparticle stabilizer. The additives affected the color, antioxidant (~90% ABTS and DPPH radicals scavenging for all melanin modified films) and antimicrobial activity (up to 4 mm grow inhibition zones of E. coli and S. aureus for both zinc oxide and silver nanoparticles), mechanical (silver nanoparticles addition effected two-fold higher tensile strength), thermal and barrier properties for water and UV-vis radiation. The addition of ZnONP resulted in improved UV barrier properties while maintaining good visible light transmittance, whereas AgNP resulted in almost complete UV barrier and reduced visible light transmittance of the obtained films. What is more, the obtained films did not have an adverse effect on cell viability in cytotoxicity screening. These films may have potential applications in food packaging or biomedical applications.

Bioactive Carboxymethyl Cellulose (CMC)-Based Films Modified with Melanin and Silver Nanoparticles (AgNPs)—The Effect of the Degree of CMC Substitution on the In Situ Synthesis of AgNPs and Films’ Functional Properties

“…The addition of silver nanoparticles led to a significant, approximately 5-fold increase in EB values. This stands in total opposition to the correlations observed for alginate [29] and polylactic acid (PLA) [46] (decrease in EB), or agar (no change in EB) [48]. On the other hand, for agar films an increase in EB values was also found [44], similarly to what was observed for PLA-based films [45], but the increases were not as significant as in this study.…”

“…All samples showed similar barrier properties against UV-Vis radiation regardless of the degree of CMC substitution used. Similar light transmission properties have also been described for such melanin-modified polymer matrices as gelatin [41], agar [40], carrageenan [42], alginate [29], cellulose [47], PBAT [43] or chitosan [50].…”

“…An opposite relationship was found for alginate films modified with silver nanoparticles synthesized using melanin. For these films, TS increased during the presence of silver nanoparticles [29]. Neither the degree of substitution nor the addition of melanin had a significant effect on the elongation at break (EB) value.…”

“…A CMC-based film sample with a degree of substitution of 0.7 modified with melanin and silver nanoparticles shows significantly higher visible radiation blocking properties than CMC 0.9 and CMC 1.2 samples modified with the same additives. modified polymer matrices as gelatin [41], agar [40], carrageenan [42], alginate [29], cellulose [47], PBAT [43] or chitosan [50]. The addition of silver nanoparticles resulted in a significant reduction in visible light transmittance and almost complete blocking of UV radiation.…”

A Comprehensive Review of Biodegradable Polymer-Based Films and Coatings and Their Food Packaging Applications

“…Organic nanoparticles are used for the targeted drug delivery of nutraceuticals in food. Three types of organic NPs are identified: lipid-based, polysaccharide-based, and protein-based [ 152 , 153 , 154 ]. These nanoparticles aid in the storage of food and the preservation of its freshness and quality [ 150 ].…”