Trends in Biotechnology
ReviewSurface biotechnology for refining cochlear implants
Section snippets
Cochlear implants and surface biotechnology
Implants are widely regarded as one of the greatest accomplishments of modern medicine. Very few surgical implants better exemplify the success that can be achieved through synergistic clinical and technological innovations than the cochlear implant. The cochlear implant is essentially a highly miniaturized electronic device that has become the standard of care for hearing restoration in patients with severe to profound sensorineural hearing loss (see Glossary). In less than 30 years, this
Enhancing cochlear implants: substitute biomaterials
The most convenient approach for implanting surface biotechnology is to simply substitute the current implant surface material with a distinctive and superior biomaterial.
Depending on their origins and chemical constituents, implant surface biomaterials can be synthetic or natural, organic or inorganic. Among the four types of biomaterial (synthetic organic, synthetic inorganic, natural organic, and natural inorganic), synthetic polymers undoubtedly have attracted the largest amount of
Enhancing cochlear implants: surface modification
In contrast to substituting with novel and high-performing biomaterials, modifying native implant surfaces makes it possible to engineer biofunctionality at the material–tissue interface for the purpose of modulating biological responses without altering material bulk attributes. Three types of surface modification have been explored: topographical, chemical, and biological (Box 1).
Topographical modification, the most exhaustively investigated approach, can be further divided into approaches
Enhancing cochlear implants: coating
In contrast to surface modifications, which involve alterations to the geometry, molecules, or compounds on the surface, coatings normally consist of an entirely different material from the underlying support (Box 1).
The most intensively studied coating type is synthetic organic (Table 1). Rapid progress within this field has revolved around three key emerging entities: conducting polymers, CNTs, and hydrogels. Conducting polymers have high electrical conductivity and tunable electrochemical
Enhancing cochlear implants: drug delivery
The fields of inner ear pharmacology and surface biotechnology progressed for many years in parallel with no substantial interaction, until the emergence of the cochlear implant, which opened the door to genuinely local and sustainable drug delivery.
The success of a cochlear implant largely depends on the proximity and availability of SGNs to the electrode. At least three methods have been used to reduce the distance between them. The first uses a surgical approach, in which a perimodiolar
Minimizing cochlear implantation-related complications
Not only can surface biotechnology enhance the performance of cochlear implants, it can also facilitate the minimization of surgical risks and complications (Box 3). Reducing intracochlear trauma caused by electrode insertion contributes significantly to the success of intraoperative hearing preservation and lessens subsequent degeneration of inner ear excitability. This goal can be pursued using two disparate strategies. The first decreases the insertion force, using either a less-invasive
Concluding remarks
The conspicuous trend in the advancement of implant biotechnology over the past half-decade is the merging of cochlear implantation and surface biotechnology into an auditory treatment based on the prosthesis–tissue interface. This new scientific endeavor focuses on maintaining stable long-term performance, impeding peri-electrode fibrous tissue formation, and promoting neurite outgrowth.
Future research will continue to refine current strategies and devise novel systems (Box 4). Intelligent all
Acknowledgment
MA-R and FT are supported by Science Foundation Ireland (grant no. 08/SRC/11411).
Glossary
- Extracellular matrix (ECM)
- tissue-specific dynamic environment that not only provides topographic architecture and mechanical support but also contains a reservoir of cell-signaling motifs and growth factors. The ECM provides the blueprint for surface biotechnology, and the balance between cell–cell and cell–ECM interactions directs auditory differentiation.
- Neurotrophin family
- this includes four members — brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin 3 (NT3),
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