&nbsp; &nbsp; &nbsp;Topical eye drop therapy serves as the most easily accessible and noninvasive treatment of ocular diseases, but its therapeutic efficacy is limited due to the corneal barriers and nasolacrimal drainage that quickly eliminates eye drops within a few minutes. Recent advances of biodegradable microneedles have led to the development of many strategies for intraocular drug delivery through the corneal barriers, which increases therapeutic efficacy. However, the clinical implementation of these microneedles in human eyes is often impeded due to their relatively large size for the human cornea and rapidly dissolving nature (typically, within 15 minutes-2 hours), which causes pain and limited therapeutic efficacy, respectively. Thus, there is a need for minimally invasive and long-term sustained drug delivery platform in treating ocular diseases.&nbsp; &nbsp; &nbsp;Vertically aligned nanomaterials, known as nanoneedles, has been crucial for gaining minimally invasive access to intratissue space and also enabling effective drug delivery strategies. Among many materials, silicon nanoneedles, due to their nanoscale size, low toxicity, and slow biodegradability, are of particular interest for long-term sustained delivery of drug molecules into living tissues. Despite many promises, the majority of current studies have relied primarily on the silicon nanoneedles bound to a bulky silicon substrate that inevitably negates the benefits of using nanoscale needles and results in mechanical mismatch with surrounding tissues. These material limitations would create a more realistic problem for their implementation in clinical practice, particularly for pain-sensitive tissues such as the cornea.&nbsp; &nbsp; &nbsp;This seminar will discuss about a critical opportunity to unlock the fundamental limits of the silicon nanoneedles in a substrate-free environment. Specifically, the first part of this seminar will elucidate (1) the structure-property-performance relationship of the silicon nanoneedles in ocular environments; (2) how to tackle the long-standing material challenges in the field of intracellular drug delivery through the design, preparation, and characterization of biodegradable silicon nanoneedles; and (3) multidisciplinary frameworks associated with the silicon nanoneedles in contact with human corneal cells and tissues. The second part of this seminar will focus on preclinical studies in treating a model ocular disease such as corneal neovascularization (i.e., the invasion of new blood vessels into the avascular cornea) which remains one of the major causes of blindness worldwide. The overarching hypothesis is that the silicon nanoneedle platform can be useful in treating corneal neovascularization by providing &gt; 30-fold smaller and &gt; 10-fold slower degradation rate as compared to current biodegradable microneedles. The evaluation of the biosafety, therapeutic efficacy, and side-effects of the silicon nanoneedles in a well-established rabbit corneal neovascularization model in vivo will be discussed, as compared to conventional anti-vascular endothelial growth factor therapy and laser therapy. Furthermore, the future potential applications of the silicon nanoneedle platform will also be discussed in the treatment of other chronic ocular diseases, including corneal, retinal, and choroidal neovascularization.

Vertically Ordered Array of Bioresorbable Si Nanoneedles for Versatile Drug Delivery Platform

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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