Mesoporous silica films as a novel biomaterial: applications in the middle ear

Abstract

In this tutorial review we present the process of the development of functional implants using mesoporous silica. The different steps from chemical synthesis and physicochemical characterization followed by in vitro testing in cell culture assays to clinically relevant in vivo animal studies are examined. Since the end of the 1990s, mesoporous silicas have been considered as biomaterials. Numerous investigations have demonstrated their non-toxic and biocompatible properties. These qualities in combination with the unique properties of high surface area and pore volume, uniform and tunable pore sizes and chemical modifiability are the reasons for the great scientific interest in this field. Here we show that besides bulk materials or mesoporous silica nanoparticles, mesoporous silica films are highly promising as coatings on medical prostheses or implants. We report on the development of functionalized mesoporous silica materials specifically for middle ear applications. Middle ear prostheses are used to restore the sound transmission through this air-filled cavity when the small bones of the middle air (the ossicular chain) have been destroyed by disease or by accidents. In addition to optimal restoration of sound transmission, this technique bears several challenges, e.g. an ongoing bacterial infection or the displacement of the prosthesis due to insufficient fixation. To improve the healing process, a mesoporous silica coating was established on ceramic middle ear prostheses, which then served as a base for further functionalizations. For example, the bone growth factor BMP2 was locally attached to the coating in order to improve the fixation of the prosthesis by forming a bony connection to the remainder of the ear bones. Further, an implant-based local drug delivery system for the antibiotic ciprofloxacin was developed with the aim of fighting bacterial infections. Further possibilities using mesoporous silica nanoparticles as part of a composite on an implant are briefly discussed. Key learning pointsThe way from clinical problems to improved implant materials: materials development, in vitro and in vivo testing. Establishment of mesoporous thin silica films on ceramic surfaces. Degradation of mesoporous silica films in physiological medium. Implant-carried mesoporous silica films as drug delivery systems. Implant-based delivery of biomolecules using mesoporous silica coatings.

Facile Synthesis of Yolk-Shell-Structured Triple-Hybridized Periodic Mesoporous Organosilica Nanoparticles for Biomedicine

“…[12][13][14] The enhanced therapeutic efficacy, reduced side effects, little biotoxicity, and degradation of mesoporous silica in the biomedical applications have been preliminary demonstrated. [15][16][17][18][19][20][21] However, the Si-O-Si frameworks of mesoporous silica still have some limitations and drawbacks in the biobehaviors and performance, and their medical translation is still a big challenge.…”

pH-responsive release of chlorhexidine from modified nanoporous silica nanoparticles for dental applications

“…Nanoporous silica materials have been investigated intensely, either as nanoparticles [18][19][20][21] or as implant surface coatings [22][23][24][25] since their first application as drug delivery platform in 2001 [26]. Nanoporous silica features various properties, which make this material interesting for a controlled release system.…”

Nanoporous Silica Films as Novel Biomaterial: Applications in the Middle Ear

“…The results obtained should be easily transferable to other types of prostheses and implants. These results have recently been summarized in a tutorial review [1].…”

“…Its functioning was established by effectively combating an intentionally placed infection of Pseudomonas aeruginosa. Furthermore, the bone growth factor BMP2 could be immobilized on the nanoporous coating under preservation of the biological activity of the protein [1].…”

“…We thank all our co-workers in the work package D1 for their enthusiasm and willingness to cooperate; they are named in the references referring to our original papers as given in ref. [1]. This work has also profited from discussions with partners from the Excellence Cluster "Hearing4All".…”