Self-powered microneedle-based biosensors for pain-free high-accuracy measurement of glycaemia in interstitial fluid

In this work a novel self-powered microneedle-based transdermal biosensor for pain-free high-accuracy real-time measurement of glycaemia in interstitial fluid (ISF) is reported. The proposed transdermal biosensor makes use of an array of silicon-dioxide hollow microneedles that are about one order of magnitude both smaller (borehole down to 4 µm) and more densely-packed (up to 1×106 needles/cm2) than state-of-the-art microneedles used for biosensing so far. This allows self-powered (i.e. pump-free) uptake of ISF to be carried out with high efficacy and reliability in a few seconds (uptake rate up to 1 µl/s) by exploiting capillarity in the microneedles. By coupling the microneedles operating under capillary-action with an enzymatic glucose biosensor integrated on the back-side of the needle-chip, glucose measurements are performed with high accuracy (±20% of the actual glucose level for 96% of measures) and reproducibility (coefficient of variation 8.56%) in real-time (30 s) over the range 0–630 mg/dl, thus significantly improving microneedle-based biosensor performance with respect to the state-of-the-art

Enforcing Multifunctionality: A Pressure-Induced Spin-Crossover Photomagnet

Photomagnetic compounds are usually achieved by assembling preorganized individual molecules into rationally designed molecular architectures via the bottom-up approach. Here we show that a magnetic response to light can also be enforced in a nonphotomagnetic compound by applying mechanical stress. The nonphotomagnetic cyano-bridged Fe^II–Nb^IV coordination polymer {[Fe^II(pyrazole)₄]₂[Nb^IV(CN)₈]·4H₂O}_<i>n</i> (<b>FeNb</b>) has been subjected to high-pressure structural, magnetic and photomagnetic studies at low temperature, which revealed a wide spectrum of pressure-related functionalities including the light-induced magnetization. The multifunctionality of <b>FeNb</b> is compared with a simple structural and magnetic pressure response of its analog {[Mn^II(pyrazole)₄]₂[Nb^IV(CN)₈]·4H₂O}_<i>n</i> (<b>MnNb</b>). The <b>FeNb</b> coordination polymer is the first pressure-induced spin-crossover photomagnet

Four-Step Access to the Sesquiterpene Natural Product Presilphiperfolan-1β-ol and Unnatural Derivatives via Supramolecular Catalysis

Terpenes constitute one of the most structurally varied classes of natural products. A wide range of these structures are produced in nature by type I terpene cyclase enzymes from one single substrate. However, such reactivity has proven difficult to reproduce in solution with man-made systems. Herein we report the shortest synthesis of the tricyclic sesquiterpene presilphiperfolan-1β-ol to date, utilizing the supramolecular resorcinarene capsule as catalyst for the key step. This synthetic approach also allows access to unnatural derivatives of the natural product, which would not be accessible through the biosynthetic machinery. Additionally, this study provides useful insight into the biosynthesis of the presilphiperfolanol natural products, including the first experimental evidence consistent with the proposed biosynthetic connection between caryophyllene and the presilphiperfolanols

TOWARDS PAIN-FREE AND HIGH-ACCURACY POINT-OF-CARE GLYCEMIC CONTROL USING CAPILLARITY-DRIVEN MICRONEEDLES

In this work, a novel class of self-powered microneedle-based transdermal biosensors for pain-free and high accu- racy measurement of glycaemia in interstitial fluid (ISF) is reported. Autonomous, effective, and fast uptake of interstitial fluid is demonstrated by exploiting capillarity in silicon dioxide microneedles with diameter of a few micrometers and density of thousands needles/cm2. Further, high accuracy and high reproducibility real-time measurement of glucose concentration in ISF is demonstrated by coupling the microneedles with an enzymatic glucose biosensor, achieving Food and Drug Administration (FDA) approved performance in-vitro. Finally, an easy-to-use handy glucometer exploiting the microneedles operating under capillary-action for (future) effective point-of-care glycaemic control is designed, fabricated, and validated in-vitro

TOWARDS PAIN-FREE AND HIGH-ACCURACY POINT-OF-CARE GLYCEMIC CONTROL USING AUTONOMOUS MICRONEEDLE-BASED SYSTEM

Microneedle systems able to measure glucose concentration in interstitial fluid (ISF) have been recently proposed for pain-free glycaemic control, as an alternative to standard finger-prick systems, following the demonstration that glucose concentration in ISF parallels that in blood, though with a delay time of 10-20 minutes. In fact, besides use of microneedles for transdermal drug delivery applications [1], in the last years an increasing number of studies is being published on their use for transdermal biosensing applications both in-situ and ex-situ, among which glucose monitoring in peripheral blood and ISF is a major target [2]. In this work, a novel class of self-powered microneedle-based transdermal biosensors for pain-free and high accuracy measurement of glycaemia in ISF is reported. Microneedle chips (silicon die 0.5 cm x 0.5 cm) integrating a two-dimensional array of silicon-dioxide hollow needles protruding from the front-side and in connection with a reservoir (18 µL volume) grooved on its back-side are designed, fabricated, and tested. The microneedles feature different pitch p (16 µm@type#A and 10 µm@type#B) and internal diameter d (6 µm@type#A and 4 µm@type#B), but same protruding length (100 µm) and inner lumen length (200 µm)