Self-assembly of colloidal lignin nanosphere particles blended with chitosan composite coated bagasse paper: An eco-friendly food packaging with antimicrobial properties

Amongst the natural polymers, chitin is the second most abundant, present mainly in fungi and exoskeleton of crustaceans. It forms a major part of the seafood waste as compiled and presented in this review and is de-acetylated to produce chitosan. Structure and properties of chitosan have been described. Biocompatible and biodegradable characteristics of chitosan have been well studied. In addition to the environmental sustainability associated with its use, the malleability of chitosan due to its reactive amino and hydroxyl groups, adds to its wide repertoire in usage through various modifications. Recent publications of chitosan and derivatives have been classified into its various applications in food, pharmaceutical, biotechnology, medical, textile, paper, agriculture and environmental applications. The abundance of chitosan and diversity in modifications can be effectively utilized in various applications leading to environmental friendly solutions as highlighted in this review.

This review gives an updated overview of the current state-of-the-art for antimicrobial chitosan and chitosan derivatives and the effects of structural modifications on activity and toxicity. The various synthetic routes introduced for chemical modification of chitosan are discussed, and the most common functional groups are highlighted. Different analytical techniques used for structural characterization of the synthesized chitosan derivatives are discussed and critically evaluated. For the purpose of this review, the antimicrobial chitosan derivatives have been classified on the basis of the type of functional group conjugated to the polymer backbone. In each case, the influence of the degree of substitution on the biological properties has been examined. Finally, we have summarized the collective information and suggested future directions for further research to improve our understanding of the bioactivity and to develop more useful chitosan conjugates.

Chitosan, a versatile hydrophilic polysaccharide derived from chitin, has a broad antimicrobial spectrum to which gram-negative, gram-positive bacteria and fungi are highly susceptible. In the current review, three possible and accepted antimicrobial mechanisms for chitosan are presented and briefly discussed. The activity dependence on polymeric molecular weight (MW) and degree of acetylation (DA) are described. The chitosan minimum inhibitory concentrations (MIC) are summarized according to recent data found in the literature. The potential to improve inhibitory growth of bacteria by using water soluble chitosan derivatives is also discussed. The data indicate that the effectiveness of chitosan varies and is dependent on species of target microorganisms.