Novel antimicrobial bioplastic based on PLA-chitosan by addition of TiO2 and ZnO

Composite cassava starch/chitosan/Pineapple Leaf Fiber (PALF)/Zinc Oxide (ZnO): Bioplastics with high mechanical properties and faster degradation in soil and seawater

Biopolymers based on starch, cellulose and proteins extracted directly from biomass with or without modification have been widely used as the natural resources to produce biodegradable plastic. Starch has several disadvantages: strong hydrophilic behavior and inferior mechanical properties when compared with synthetic polymers. Starch is also mostly soluble in water and will be decomposed before undergoing the gelatinization process. To provide resistance and mechanical strength of starch, several fillers (reinforcement) in the form of metal and natural materials are usually added to the polymer matrix. Zinc oxide (ZnO) nanoparticle and natural fiber as a lightweight material that is biocompatible, nontoxic, cost-effective and exhibit strong antibacterial activity can be considered as a reinforcement of starch-based bioplastic. The present study, the reinforcing effect of ZnO on the mechanical, antibacterial, and physical properties of bioplastic films in the form of cassava starch/chitosan/pineapple leaf fiber (PALF)/ZnO. The highest value of elongation at break is for 16 % ZnO-bioplastics which could be completely decomposed only 21 days in ordinary soil and only 18 days in seawater. The packaging tests using slice bread showed antimicrobial properties with no fungal growth for 30 days of bioplastic coatings with 10, 13, and 16 % ZnO NPs. The results in this study indicated that, the ZnO and PALF plays an important role in reinforcing the physical, mechanical, and antibacterial properties of starch/chitosan/PALF-based bioplastic.

Preparation of Cotton-Zinc Composites by Magnetron Sputtering Metallization and Evaluation of their Antimicrobial Properties and Cytotoxicity

The aim of this investigation was to evaluate the biological properties of cotton-zinc composites. A coating of zinc (Zn) on a cotton fabric was successfully obtained by a DC magnetron sputtering system using a metallic Zn target (99.9%). The new composite was characterized using scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), UV/Vis transmittance, and atomic absorption spectrometry with flame excitation (FAAS). The composite was tested for microbial activity against colonies of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and antifungal activity against Aspergillus niger and Chaetomium globosum fungal mold species as model microorganisms. Cytotoxicity screening of the tested modified material was carried out on BALB/3T3 clone mouse fibroblasts. The SEM/EDS and FAAS tests showed good uniformity of zinc content on a large surface of the composite. The conducted research showed the possibility of using the magnetron sputtering technique as a zero-waste method for producing antimicrobial textile composites.