Advanced biotechnological applications of bacterial nanocellulose-based biopolymer nanohybrids: A review

Abstract

Bacterial nanocellulose (BNC), as a natural polymer, produced in vivo by bacteria and in vitro by the cell-free enzymes system, is comprised of nano-sized fibers. The pristine BNC possesses unique structural, physiological, and biological properties. Its fibrous and porous morphology allows the incorporation of natural and synthetic polymers, nanomaterials, clays, etc., while the presence of free hydroxyl (OH) groups allows its chemical modification with a variety of functional groups to form nanohybrids. These hybrids not only have superior properties to those of pristine BNC but possess additional functionalities imparted by the reinforcement materials. The properties of BNC-based nanohybrids can be tuned at macro, micro, and nano-scales as well as controlled at molecular levels. This review consolidates the current knowledge on the synthesis of β-(1,4)-glucan chains, their excretion and organization into high-ordered nano-sized fibers, as well as functionalization, both at physiological and molecular levels. It comparatively discusses the microbial and cell-free synthesis of cellulose and discusses the potential merits and limitations of each method. It further explores the methods used for developing BNC-based hybrids and discusses the synthesis-structure-properties relationship of BNC-based hybrids to justify their use for targeted biotechnological applications. A large portion of this review is devoted to discussing the recent trends in the preparation of BNC-based nanohybrids for their biotechnological applications, including biomedical (i.e., wound healing, cardiovascular devices, neural tissues, bone and cartilage tissues, dental implants, and drug delivery) and non-biomedical (biosensing, cosmetics, food, bio- and optoelectronics, environment, energy, and additive manufacturing). Finally, it provides an outlook on the future BNC research for human welfare.