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.

Green synthesis of nanoparticles for use in food packaging or biomedical applications is attracting increasing interest. In this study, the effect of the degree of substitution (0.7, 0.9 and 1.2) of a carboxymethylcellulose polymer matrix on the synthesis and properties of silver nanoparticles using melanin as a reductant was investigated. For this purpose, the mechanical, UV-Vis barrier, crystallinity, morphology, antioxidant and antimicrobial properties of the films were determined, as well as the color and changes in chemical bonds. The degree of substitution effected noticeable changes in the color of the films (the L* parameter was 2.87 ± 0.76, 5.59 ± 1.30 and 13.45 ± 1.11 for CMC 0.7 + Ag, CMC 0.9 + Ag and CMC 1.2 + Ag samples, respectively), the UV-Vis barrier properties (the transmittance at 280 nm was 4.51 ± 0.58, 7.65 ± 0.84 and 7.98 ± 0.75 for CMC 0.7 + Ag, CMC 0.9 + Ag and CMC 1.2 + Ag, respectively) or the antimicrobial properties of the films (the higher the degree of substitution, the better the antimicrobial properties of the silver nanoparticle-modified films). The differences in the properties of films with silver nanoparticles synthesized in situ might be linked to the increasing dispersion of silver nanoparticles as the degree of CMC substitution increases. Potentially, such films could be used in food packaging or biomedical applications.

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

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.

Antimicrobial, Antibiofilm, and Antioxidant Activity of Functional Poly(Butylene Succinate) Films Modified with Curcumin and Carvacrol.

The use of food industry waste as bioactive compounds in the modification of biodegradable films as food packaging remains a major challenge. This study describes the preparation and bioactivity characterization of poly(butylene succinate) (PBS)-based films with the addition of the bioactive compounds curcumin (CUR) and carvacrol (CAR). Films based on PBS modified with curcumin and carvacrol at different concentration variations (0%/0.1%/1%) were prepared by solvent casting method. The antioxidant, antimicrobial, and antibiofilm properties were investigated against bacteria (Escherichia coli, Staphylococcus aureus) and fungi (Candida albicans). As a result of the modification, the films exhibited free radicals scavenging (DPPH up to 91.47% and ABTS up to 99.21%), as well as antimicrobial (6 log, 4 log, and 2 log reductions for E. coli, S. aureus, and C. albicans, respectively, for samples modified with 1% CUR and 1% CAR) activity. Moreover, antibiofilm activity of modified materials was observed (8.22-87.91% reduction of biofilm, depending on bioactive compounds concentration). PBS films modified with curcumin and carvacrol with observed bifunctional properties have many potential applications as active packaging.

Development and Characterization of Bioactive Poly(butylene-succinate) Films Modified with Quercetin for Food Packaging Applications.

The preparation of biodegradable active packaging materials is still a major challenge. Here, we report the fabrication and characterization of poly(butylene succinate)-based (PBS) films enriched with a natural polyphenolic antioxidant-quercetin. The PBS-based films with various quercetin content (0.05; 0.10; 0.25 and 0.50 pph on PBS) were prepared via a solvent casting method. Physical (optical, mechanical, thermal, moisture and water sorption, water vapor and UV-vis barrier) and biofunctional (antioxidant and antibacterial against Escherichia coli and Staphylococcus aureus) film properties were tested. The migration of quercetin into model food liquid systems was determined. As a result of quercetin addition, significant changes in color, opacity and UV-blocking effect were observed. The presence of the active substance did not significantly affect the thermal properties of the PBS matrix. However, the mechanical properties of the films were slightly decreased. The films exhibited excellent free radicals (DPPH, ABTS, O2-) scavenging and some bactericidal activities. PBS-quercetin films with superior functional properties have many possibilities for active food packaging applications.