Biosensing systems based on microneedles can overcome the stratum corneum of the skin, i. e. the outer natural barrier of the human body, without any pain and detect the target analytes directly in the interstitial fluid. Moreover, microneedle-based devices (MNDs) can combine diagnostic sensing and therapeutic administration of drugs in one single tool. From this point of view, more than a painless door to the human body, a MND represents the a perfect example of theranostic instrument, since a single device could quantify the real value of a relevant biomolecule, such asglucose, and accurately deliver a drug, the insulin, if needed. MNDs could be integrated on printed circuit boards, flexible electronics and microfluidic channels, thus allowing a continuous monitoring of the physiological parameters with very low invasiveness, together with sustained and localized administration of drugs. In fact, the transdermal route for drug administration is a very fascinating way, not only for the very low invasiveness and the easiness of self administration, but also for the absence of first pass metabolism. However, the intercellular lipid matrix of the epidermis consists of ceramides, free fatty acids, and cholesterol, a complex mixture of neutral lipids arranged as bilayers with hydrophobic chains facing each other (lipophilic bimolecular leaflet). Transdermal delivery works only for lipophilic uncharged drugs with low MW (<500 Da), which needs low dose and continuous delivery. MNs can be used with both lipophilic and hydrophilic formulations, both charged and uncharged drugs, both small and oversized molecules. For all these cases, MN configurations are illustrated, where the possibility to use solving or hybrid soluble/insoluble MNs are considered. MNDs can be designed for very specific applications, from the detection of skin cancer to the monitoring of metabolic pathways. Moreover, several fabrication approaches have been introduced, from laboratories to large scale production.
Principia Dardanois responsible for the design, fabrication and optical characterization of optoelectronic silicon devices. She received his Ph.D. in Fundamental and Applied Physics at the same university in January 2008, with thesis on negative refractive index 2D photonic crystals in silicon. She is working at the Institute of Applied Science and Intelligent Systems (ISASI-CNR) in Naples, where she is the head of the photolithographic laboratory since 2006. She holds treeUS patent, and one Italian patent.
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