Macromolecular Architecture of Self-Healing Bio-Films Incorporating Cryoprotective Additives: Biopolymer Design Strategies for Plant Wound and Frost Management — A Comprehensive Review

Plant wounds created by pruning, grafting, mechanical damage, or pest activity remain persistently vulnerable to microbial invasion and environmental stress, particularly during cold and transitional seasons. Most traditional wound sealants are inert, petroleum based and unable to adapt to the changing conditions that plants encounter following wounding. This review outlines another approach: the design of bio-based macromolecular systems, which are able to physically protect plant wounds, and also serve as integrated cryoprotection against frost damage. Combining current knowledge on the structural biology of antifreeze proteins (AFPs) and their ice-binding mechanisms, on the self-healing chemistry of biopolymer networks (chitosan, alginate, bacterial cellulose and curli-fiber composite), and on the macromolecular composition of microbial extracellular polymeric substances (EPS), we arrive at a present knowledge about how these macromolecular building blocks could be combined into multifunctional systems for wound protection. PubMed, Web of Science and Scopus (2000–2025) databases were searched systematically: The search terms were ‘antifreeze proteins’, ‘self-healing hydrogels’, ‘biopolymer wound dressings’, ‘extracellular polymeric substances’ and ‘plant cryoprotection’. We critically examine AFP structural features particularly the β-roll ice-binding domains of cereal AFPs and the leucine-rich repeat (LRR) motifs of carrot AFP and compare their thermal hysteresis (TH) and ice recrystallisation inhibition (IRI) activities. We then review the dynamic covalent and supramolecular mechanisms underlying self-healing in biopolymer networks (Schiff base, disulfide, hydrogen bonding, catechol metal coordination). The integration of AFPs into hydrogel matrices is discussed as a proposed research direction, with honest acknowledgement that combined AFP hydrogel systems have not yet been validated in plant wound contexts. Key challenges including AFP production cost, in planta stability, phytotoxicity risk, and regulatory considerations are addressed directly. This review positions the International Journal of Biological Macromolecules readership to identify the specific macromolecular design questions that must be answered before these integrated systems can advance from concept to application.