Development and application of a ratiometric nanosensor for measuring pH inside the gastrointestinal tract of zooplankton
Development and application of a ratiometric nanosensor for measuring pH inside the gastrointestinal tract of zooplankton
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DOI：
10.1039/c9en01300h
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发表时间：
2020-06-01
影响因子：
7.3
通讯作者：
Shi, Zongbo
中科院分区：
文献类型：
--
作者：
Davis, Adam;Nasser, Fatima;Shi, Zongbo
浮游动物胃肠道内的pH值调节营养素和无机毒素（金属、纳米颗粒）的生物利用度以及摄入食物的分解。然而，测量浮游动物胃肠道pH值的空间分布是具有挑战性的，因为胃肠道的尺寸非常小，其微环境复杂。在这里，我们开发了一种二氧化硅掺杂的比率纳米传感器能够映射pH值在整个胃肠道的浮游动物。通过将pH敏感染料-荧光素5-异硫氰酸酯和pH不敏感染料（作为参考）-罗丹明B缀合到惰性二氧化硅纳米颗粒上来制备直径为79.0 +/-25.0 nm的纳米传感器。新的纳米传感器具有5至8的pH传感范围，适用于确定微生物胃肠道的pH。为了证明纳米传感器的应用，我们将它们喂给一种模式生物Daphnia magna neonates，以绘制其胃肠道内的pH值。结果表明，胃肠道前段的pH值为5.5-6.0，后段的pH值高达7.2。总的来说，D.大胃肠道明显低于周围的水介质（pH = 7.8）。这表明D.大型果蝇新生幼虫能够调节其内部pH值。麦格纳可以增加营养物的溶解度（例如，氧化铁）或毒素（例如，银纳米颗粒）的数量级，提供了表面沃茨中可溶性营养物和/或毒素的潜在重要来源。
The pH within the gastrointestinal (GI) tract of zooplankton regulates the bioavailability of nutrients and inorganic toxins (metals, nanoparticles) and the breakdown of ingested food. However, measuring the spatial distribution of pH in the GI tract of zooplankton is challenging because the size of the GI tract is extremely small and its micro-environment is complex. Here, we developed a silica-doped ratiometric nanosensor capable of mapping pH in the whole GI tracts of zooplankton. The nanosensors, 79.0 +/- 25.0 nm in diameter, were prepared by conjugating pH sensitive dye - fluorescein 5-isothiocyanate and pH insensitive dye (as a reference) - Rhodamine B, to an inert silica nanoparticle. The new nanosensors have a pH sensing range from 5 to 8 which is suitable for determining the pH of the gastrointestinal tract of microorganisms. To demonstrate the application of the nanosensors, we fed them to a model organism Daphnia magna neonates to map the pH inside their GI tracts. The results show that the pH was 5.5-6.0 at the anterior section of the GI tract and up to 7.2 in the posterior section. Overall, the pH within the D. magna GI tract was significantly lower than the surrounding aqueous medium (pH = 7.8). This indicates that D. magna neonates are able to regulate their internal pH. Such a low pH in the anterior part of the GI tract of D. magna can increase the solubility of nutrients (e.g., iron oxides) or toxins (e.g., silver nanoparticles) by orders of magnitude, providing a potentially important source of soluble nutrients and/or toxins in surface waters.