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Micromachines 2018, 9(1), 40;

In Vivo Experimental Study of Noninvasive Insulin Microinjection through Hollow Si Microneedle Array

Laboratory of Microsensor Structures and Electronics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia
Department of Endocrinology, Diabetes and Metabolic Diseases, University Medical Centre Ljubljana, Zaloška 7, SI-1000 Ljubljana, Slovenia
National Institute for Research and Development in Microtechnologies, IMT-Bucharest, Bucharest 077190, Romania
Author to whom correspondence should be addressed.
Received: 25 October 2017 / Revised: 2 January 2018 / Accepted: 16 January 2018 / Published: 20 January 2018
(This article belongs to the Special Issue Silicon-based Micro/Nanofabrication for Biomedical Applications)
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An experimental study of in vivo insulin delivery through microinjection by using hollow silicon microneedle array is presented. A case study was carried out on a healthy human subject in vivo to determine the influence of delivery parameters on drug transfer efficiency. As a microinjection device, a hollow microneedle array (13 × 13 mm2) having 100 microneedles (220 µm high, 130 µm-outer diameter and 50 µm-inner diameter) was designed and fabricated using classical microfabrication techniques. The efficiency of the delivery process was first characterized using methylene blue and a saline solution. Based on these results, the transfer efficiency was found to be predominantly limited by the inability of viable epidermis to absorb and allow higher drug transport toward the capillary-rich region. Two types of fast-acting insulin were used to provide evidence of efficient delivery by hollow MNA to a human subject. By performing blood analyses, infusion of more-concentrated insulin (200 IU/mL, international units (IU)) exhibited similar blood glucose level drop (5–7%) compared to insulin of standard concentration (100 IU/mL), however, significant increase of serum insulin (40–50%) with respect to the preinfusion values was determined. This was additionally confirmed by a distinctive increase of insulin to C-peptide ratio as compared to preinfusion ratio. Moreover, we noticed that this route of administration mimics a multiple dose regimen, able to get a “steady state” for insulin plasma concentration. View Full-Text
Keywords: hollow Si microneedle array; microinjection; in vivo insulin delivery; drug transfer efficiency hollow Si microneedle array; microinjection; in vivo insulin delivery; drug transfer efficiency

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Resnik, D.; Možek, M.; Pečar, B.; Janež, A.; Urbančič, V.; Iliescu, C.; Vrtačnik, D. In Vivo Experimental Study of Noninvasive Insulin Microinjection through Hollow Si Microneedle Array. Micromachines 2018, 9, 40.

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