Ultra-tiny-scale technology for engineering human ear therapeutics

Ultra-tiny-scale technology representing engineered micro- and nano-scale materials has gained considerable attention for a wide range of applications, including hearing restoration. The advent of hearing loss and its recovery has been the topic of intense discussion since many decades. Although conventional treatments partially support hearing recovery, they present certain limitations such as subsequent immune response and donor site morbidity leading to even worsened sensory disturbances. Microscale- and nanoscale-based approaches such as tissue engineering, nanoparticle-assisted drug delivery systems, and micro/nanofabrication-aided auditory stimulations have been shown to play an efficient role in recovery from hearing disorders. In particular, the introduction of different biomaterials and biopolymers (natural and synthetic) with influential topographical cues and excellent biocompatibility has been found to conveniently bypass previous challenges posed by rigid human ear structures and provided a new path for improved and advanced hearing-recovery approaches. This review is focused on the development of micro/nanoengineering-based hearing recovery therapeutics and their significant impact on the future of hearing research. It discusses the physiological functions associated with the human ear and the mechanism underlying distinct hearing loss disorders as well as highlights various engineered ultra-tiny-scale-assisted strategies for developing advanced hearing therapeutics. Finally, we deliberate on commercialization aspect and future perspectives of implementing micro/nanotechnologies for hearing restoration platforms.