Résumé
Cellulose nanocrystals (CNCs) have garnered a tremendous amount of research interest over the last decade or so for enhanced health and life sciences applications due to their special properties of unique morphology or geometrical orientation, rheological characteristics, switchable crystallinity, high values of specific surface area, high mechanical strength, barrier properties, surface chemical reactivity, biocompatibility, environmentally benign nature, low toxicity/cytotoxicity, and so on. Like CNC, other wonderful materials, namely, polyethylene oxide (PEO) and polyethylene terephthalate (PET) hydrogels, warrant significant attention in the same regard, on account of their biocompatibility, biodegradability, lack of toxicity/cytotoxicity, permeability, and so on. The present chapter discusses the emergence of CNC and PEO/PET hydrogels along with their copolymer PEO–PET as novel materials in biotechnology and biomedicine. Starting with the historical background and unique physical, chemical, and biological characteristics and properties, their establishment, as feasible and viable material in biotechnological and biomedical applications like tissue engineering, medical implants, antimicrobial activity, enzyme/protein immobilization, cancer targeting, is thoroughly discussed with selected and latest examples. Significant findings and results in this regard are also em‐phasized. Finally, new frontiers with future strategies and possible research points on these materials are also highlighted.