Interfacing Perforated Eardrums with Graphene-Based Membranes for Broadband Hearing Recovery

Advancing piezoelectric 2D nanomaterials for applications in drug delivery systems and therapeutic approaches

Precision drug delivery and multimodal synergistic therapy are crucial in treating diverse ailments, such as cancer, tissue damage, and degenerative diseases. Electrodes that emit electric pulses have proven effective in enhancing molecule release and permeability in drug delivery systems. Moreover, the physiological electrical microenvironment plays a vital role in regulating biological functions and triggering action potentials in neural and muscular tissues. Due to their unique noncentrosymmetric structures, many 2D materials exhibit outstanding piezoelectric performance, generating positive and negative charges under mechanical forces. This ability facilitates precise drug targeting and ensures high stimulus responsiveness, thereby controlling cellular destinies. Additionally, the abundant active sites within piezoelectric 2D materials facilitate efficient catalysis through piezochemical coupling, offering multimodal synergistic therapeutic strategies. However, the full potential of piezoelectric 2D nanomaterials in drug delivery system design remains underexplored due to research gaps. In this context, the current applications of piezoelectric 2D materials in disease management are summarized in this review, and the development of drug delivery systems influenced by these materials is forecast.

Comparison of healing of acute total tympanic membrane perforation between rats with and without excision of the mallear handle

Objective

We compared the histological changes and hearing restoration during the healing of acute total tympanic membrane (TM) perforations between Sprague-Dawley (SD) rats with and without excision of the mallear handle.

Materials and methods

Bilateral, acute, and total TM perforations were created in 36 male SD rats. The mallear handle was preserved in the left ear (handle-preserved ear [HPE]) and excised from the right ear (handle-excised ear [HEE]). Endoscopical examination, auditory brainstem response (ABR) thresholds, histopathological, and scanning electron microscope (SEM) analysis were performed.

Results

Endoscopic photographs showed that all perforations in the 18 SD rats were closed. The mean closure times were 6.83 ± 0.85 and 8.50 ± 0.71 days in the HPE and HEE groups, respectively (p < .001). SEM images showed radial arrangement of fiber bundles in a single direction in HPEs, although normal arrangement was not achieved. In contrast, HEEs showed disorganized arrangement. At 1 month after perforation closure, the ABR thresholds at high frequencies were significantly higher in the HEE group than in the HPE group (p = .029 and p = .017 for 16 and 32 kHz, respectively). Additionally, the changes in ABR threshold were significantly different at high frequencies (p = .011 and p = .017 for 16 and 32 kHz, respectively) before and 1 month after perforation closure between the HPE and HEE groups, although the differences were not statistically significant at the remaining frequencies.

Conclusion

Although the malleus handle may not affect the closure of total perforation in SD rats, it contributes to accelerate the perforation closure by possible guide the migration of proliferative epithelial cell on the upper halves of the annulus. Additionally, resection of the malleus handle impairs high frequency hearing recovery following spontaneous closure of the TM.

Stem cells as potential therapeutics for hearing loss

Hearing impairment is a global health problem. Stem cell therapy has become a cutting-edge approach to tissue regeneration. In this review, the recent advances in stem cell therapy for hearing loss have been discussed. Nanomaterials can modulate the stem cell microenvironment to augment the therapeutic effects further. The potential of combining nanomaterials with stem cells for repairing and regenerating damaged inner ear hair cells (HCs) and spiral ganglion neurons (SGNs) has also been discussed. Stem cell-derived exosomes can contribute to the repair and regeneration of damaged tissue, and the research progress on exosome-based hearing loss treatment has been summarized as well. Despite stem cell therapy's technical and practical limitations, the findings reported so far are promising and warrant further investigation for eventual clinical translation.

Applications of Graphene in Five Senses, Nervous System, and Artificial Muscles

Graphene remains of great interest in biomedical applications because of biocompatibility. Diseases relating to human senses interfere with life satisfaction and happiness. Therefore, the restoration by artificial organs or sensory devices may bring a bright future by the recovery of senses in patients. In this review, we update the most recent progress in graphene based sensors for mimicking human senses such as artificial retina for image sensors, artificial eardrums, gas sensors, chemical sensors, and tactile sensors. The brain-like processors are discussed based on conventional transistors as well as memristor related neuromorphic computing. The brain-machine interface is introduced for providing a single pathway. Besides, the artificial muscles based on graphene are summarized in the means of actuators in order to react to the physical world. Future opportunities remain for elevating the performances of human-like sensors and their clinical applications.