This study presents an in vivo optical hydrogel microneedle platform that measures levels of analytes in interstitial fluid. The platform builds on a previously published technique for molding hydrogel microneedles by developing a composite hydrogel (i.e., PEGDA and polyacrylamide) that is sufficiently stiff to penetrate skin in the hydrated state and whose fluorescence changes dynamically—via a conjugated aptamer—depending on level of analyte. In a demonstration relevant to hypercalcemia, the hydrogel microneedle distinguished varying concentrations of calcium (within a range of 0 to 2 mM, which spans physiologically meaningful variations for hypoparathyroidism) within 10 minutes. In rats, a compact CMOS sensor measuring fluorescence from microneedles distinguished low hypercalcemic (1.7 mM) from high hypercalcemic (2.3 mM) ionized calcium levels as determined from reference blood measurements. Overall, this work demonstrates in vivo feasibility of a concept—which we call mPatch—for an optical hydrogel microneedle to measure small changes in levels of analytes in interstitial fluid, which does not rely on extraction of interstitial fluid out of the dermis.

中文翻译：

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mPatch：一种可穿戴水凝胶微针贴片，用于钙的体内光学传感


本研究提出了一种体内光学水凝胶微针平台，用于测量间质液中分析物的水平。该平台基于先前发表的模塑水凝胶微针技术，开发了一种复合水凝胶（即 PEGDA 和聚丙烯酰胺），该复合水凝胶具有足够的刚度，可以在水合状态下穿透皮肤，并且其荧光通过共轭适配体动态变化，具体取决于分析物的水平。在与高钙血症相关的演示中，水凝胶微针在 10 分钟内区分了不同浓度的钙（在 0 至 2 mM 的范围内，这跨越了甲状旁腺功能减退症的生理意义变化）。在大鼠中，一个紧凑的 CMOS 传感器测量微针的荧光，从参考血液测量中确定，区分低高钙血症 （1.7 mM） 和高高钙血症 （2.3 mM） 离子钙水平。总体而言，这项工作证明了光学水凝胶微针概念（我们称之为 mPatch）的体内可行性，用于测量间质液中分析物水平的微小变化，它不依赖于从真皮中提取间质液。