Bio-Based Nanocomposite Films Prepared from Tamarind Seed Xyloglucan and Seed Coat–Derived Carbon Dots

Abstract

Since India is the major tamarind producer in the world, the current research focuses on tamarind kernel xyloglucan (XG) as a biodegradable polymer backbone in the fabrication of multifunctional nanocomposite films. The tamarind seed coat biomass was converted into carbon dots (CDs) and added into the XG matrix in different concentrations (1-5% w/w) to enhance functionality of films. The fluorescence spectroscopy was used to characterize the synthesized CDs. The structural, mechanical, barrier, optical and functional properties of the films were assessed in a systematic manner under the impact of CD incorporation. Spectroscopic (FTIR) and crystallographic (XRD) studies established improved intermolecular interactions, which were mainly based on the hydrogen bonding between the functional groups on the surface of the CD and the hydroxyl-containing XG chains. Such interactions led to better structural cohesion and the performance of the film in general. The nanocomposite film that had 4% of CDs had the best combination of properties among the various formulations. This formulation was characterized by higher tensile strength and elastic modulus, low water vapor permeability, high surface hydrophobicity, better UV-shielding and high antioxidant capacity. Also, the films exhibited antimicrobial activities on Escherichia coli and Bacillus subtilis. Nevertheless, with increased concentration of CD (5% w/w) partial agglomeration of nanoparticle was observed, resulting in a lower film homogeneity and performance. In general, the results indicate the potential of optimized XG/CD4% nanocomposite film as a sustainable and active food packaging material, and has promising further uses in shelf life and food safety.