Real-time quantification of salicylic acid with a fiber optic sensor functionalized by gold nanoparticles-copper metal organic conjugate coating
Real-time quantification of salicylic acid with a fiber optic sensor functionalized by gold nanoparticles-copper metal organic conjugate coating
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DOI：
10.1117/12.2605711
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发表时间：
2022-06
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影响因子：
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通讯作者：
Shawana Tabassum
中科院分区：
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作者：
Shawana Tabassum
水杨酸(SA)是植物诱导防御机制的重要调节因子。据报道，在许多干旱、盐和冷/热胁迫的植物中，以及在病原体/食草动物攻击之后，SA水平都发生了渐进性变化。因此，实时和现场监测这种植物激素将有助于及早识别作物逆境，以便能够立即采取干预措施，以减少生产力损失并保持产品质量(例如，农产品和棉纤维的质量)。然而，目前的技术缺乏现场和本地化的分析能力，限制了它们在农作物领域的使用。为此，本工作报道了一种基于LSPR(局域表面等离子体共振)的光纤传感器，该传感器具有金纳米颗粒和铜基金属有机骨架(CuMOF)的共轭功能，用于选择性地测量汁液中的SA水平。为此，在光纤的远端涂覆了金纳米颗粒，这种纳米颗粒在光的电磁场激励下表现出LSPR。利用CuMOF对SA进行选择性氧化，实现了纳米金包覆纤维的共价功能化。这种氧化反应导致局部折射率的变化，从而导致LSPR强度水平的变化。该光纤尖端传感器的灵敏度为每μM SA浓度高达0.0117%的光反射变化，检测极限为37μM。光纤尖端传感器也被证明可以测量活植物茎中的SA水平。考虑到良好的动态检测范围(100-1000μM)和灵敏的硫醇化学，所开发的传感器有望在未来用于实时测量汁液中植物激素的原位探针。
Salicylic acid (SA) is a vital regulator of induced defense mechanisms in plants. Progressive variations in the SA levels have been reported in many droughts, salt, and cold/heat-stressed plants, as well as after pathogen/herbivore attacks. Hence, real-time and in situ monitoring of this phytohormone will facilitate the early identification of crop stresses so that immediate interventions can be implemented to mitigate productivity losses and maintain the quality of the product (e.g., quality of produce and cotton fibers). However, the lack of in situ and localized analysis capabilities in current technologies limits their use in crop fields. Toward this endeavor, this work reports an LSPR (localized surface plasmon resonance)- based fiber-optic sensor functionalized with a conjugate of gold nanoparticles and copper-based metal-organic framework (CuMOF) for selectively measuring SA levels in sap. For this purpose, the distal end of an optical fiber was coated with gold nanoparticles that exhibited LSPR upon excitation by light’s electromagnetic field. The gold nanoparticles-coated fiber was covalently functionalized with CuMOF, which selectively oxidized SA. This oxidation reaction resulted in a variation in the local refractive index, thereby leading to a change in the LSPR intensity level. The fiber-tip sensor exhibited a sensitivity of up to 0.0117 % light reflection variations per μM concentration of SA and a limit of detection of 37 μM. Plant sap was used to calibrate the sensor for precision measurements. The fiber-tip sensor was also demonstrated to measure the SA levels in the stem of a live plant. Considering excellent dynamic detection range (100-1000 μM) and sensitive thiol chemistry, the developed sensor could hold promises in future in situ probe development for real-time measurements of phytohormones in sap.