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Natural active compounds with antioxidant properties and other potential health benefits, like quercetin (Qu), have aroused wide concern for developing bio-functional products. However, their applications are hindered by their intrinsic poor water solubility and chemical instability. In this paper, a natural antioxidant alpha lipoic acid (ALA) was grafted onto chitosan (CS) to synthesize a novel graft polymer (CS-graft-ALA). In particular, this graft-polymer could self-assemble into spherical nanomicelles in water, with a low critical micelle concentration (CMC) of 0.0076 mg/mL. As a robust and active nanocarrier, the CS-graft-ALA micelles showed high efficiency in encapsulating Qu and dispersing Qu in water. As found, the antioxidant activity of Qu was effectively enhanced when entrapped within CS-graft-ALA micelles. Moreover, CS-graft-ALA micelles could significantly improve the photo-stability and temperature-stability of Qu. The Qu/CS-graft-ALA micelles with excellent water dispersability, stability and improved antioxidant activity hold a great potential for wide applications., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Natural antioxidants are beneficial additives for active packaging due to their ability to resist oxidative damage. Polymeric micelles are effective in delivering natural antioxidants in aqueous environments. However, individual encapsulation of a single antioxidant may not be sufficient to meet the needs of modern food packaging. A dual natural antioxidant‐loaded micellar system (i.e., vitamin E [VE] and curcumin [Cur]) was developed to achieve combined functionality and high loading concentration. Chitosan‐graft‐oleic acid (CSOA) micelles were employed as carriers to co‐encapsulate VE and Cur through a facile ultrasound‐assisted self‐assembly method. The prepared VE and Cur co‐loaded micelles (CSOA/VE/Cur) exhibited a uniform spherical structure with an average particle size of 210.6 nm and a zeta potential of +29.5 mV. Moreover, the co‐encapsulation of VE and Cur showed a significant enhancement in both entrapment efficiency, loading capacity and stability as compared to the individual encapsulation of either VE or Cur. In addition, the CSOA/VE/Cur micelles showed improved antioxidant activity than free VE/Cur at the same concentrations, as evidenced by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. Moreover, the micellar materials were utilized to fabricate regenerated cellulose (RC) films with antioxidant properties, highlighting their potential as additives for antioxidant active packaging. [ABSTRACT FROM AUTHOR]

β-Carotene (β-C) is a well-established natural antioxidant agent, but its poor water-solubility, low chemical stability and low bioavailability limit its application in food, pharmaceuticals and cosmetics industries. Thus it is critical to develop an efficient method to improve the water solubility and stability of β-C. In this research, amphiphilic chitosan-graft-poly (lactide) (CS-g-PLA) copolymer was synthesized via a homogeneous ring-opening polymerization (ROP) in ionic liquid. The obtained CS-g-PLA copolymer was able to self-assemble into about 14 nm micelles in water at low concentration, and β-C loaded micelles (β-C/M) had low β-C degradation after 15 days. The antioxidant properties of the β-C/M were investigated by the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method and ferric reducing antioxidant power (FRAP) method, respectively. Significantly improved antioxidant activity was observed for β-C/M in compare with free β-C. The aqueous dispersion of β-C/M has potential to be applied in the field of functional food and cosmetics. [ABSTRACT FROM AUTHOR]

• Dynamic cross-linked composite hydrogels were prepared. • Stretchability and mechanical stability of the hydrogels were enhanced by CNF. • Good self-healing property and moldability of the hydrogels were performed. • The hydrogels exhibited antioxidant and antibacterial activities. Here, we designed a self-healing composite hydrogel with antioxidant and antibacterial activities by using cellulose nanofibrils (CNF) and tannic acid (TA) as functional additives. Excellent mechanical stability, moldability, stretchability and rapid self-healing ability without any external intervention were realized in one system due to the combined dynamic borate ester bonding between polyvinyl alcohol-borax (PB) and multi-hydrogen bonding between different components. The rheological measurements indicated the incorporation of CNF and TA to PB system substantially affected the viscoelasticity of hydrogels. The unique antioxidant and antibacterial properties were achieved due to the complexation of TA. These high performance multifunctional hydrogels opens a window for a broad application in the field of smart devices and surface engineering. [ABSTRACT FROM AUTHOR]