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环境雌激素 (environmental estrogens,EEs) 是具有内分泌干扰效应的类固醇类物质[1]。17β-雌二醇 (17β-estradiol,E2) 是由性腺分泌的一种具有较高生物活性的天然雌激素,可以通过牲畜粪便和污水排放进入水环境,从而进入生物体内,即使较低浓度的E2也会干扰人体及动物体的正常内分泌功能并使生理系统紊乱[2-4]。
目前,常用的E2检测技术主要包括高效液相色谱法 (HPLC) [5-6]、液相色谱-质谱联用法 (LC-MS) [7-8]、气相色谱-质谱联用法 (GC-MS) [9]、免疫分析法[10-11]、电化学分析法[12-13]等。虽然色谱法具有灵敏度高、准确度高的优点,但由于实际样品的复杂性和E2的痕量或超痕量残留,需要经过复杂的预处理过程,因此不适用于现场快速检测[4]。免疫分析法具有较高的灵敏度,但是缺乏特异性且抗干扰能力弱。电化学方法检测E2具有灵敏度高和成本低的优点,但是E2的电化学活性较弱,检测过程中需要较高的氧化电位,这可能会导致电极钝化,造成检测的特异性和可重复性较差。因此,开发一种简便、快速、灵敏度高、特异性好且可实现现场检测雌二醇的方法势在必行。
荧光法因其灵敏度高、重现性好、操作简便等优点受到研究人员的广泛关注[14]。荧光检测方法中使用的荧光元件一般包括荧光染料、量子点和生物荧光团[15]。碳量子点 (CQDs) 凭借其荧光性能稳定、生物相容性好、水溶性好、低毒性、易合成、生产成本低等优点,现已广泛应用于构建环境和食品中有害物质检测的荧光传感器[16-18]。
核酸适配体 (aptamer) 是可以折叠成特定三级空间结构的,通过空间构型互补与目标分子高亲和性、高特异性结合的一段寡核苷酸序列,具有亲和性强、特异性高、合成简单、稳定性好等优点[19-20]。目前,核酸适配体传感器已被广泛应用于金属离子、有机分子、胺肽、蛋白质、以及细胞等方面的检测,而且均表现出良好的检测效果[21-24]。
为减少资源浪费,实现技术的可持续发展,低价值废物转化为高价值生物质的研究越来越受欢迎[25]。甘蔗渣是世界上最大的农作物废弃物之一,具有产量大、产地集中、成本低、性能稳定等优点,有利于工业化生产[26]。由于甘蔗渣具有较高的半纤维素含量和丰富的碳、氧元素[27],且其灰分含量低于其他农业废弃物。因此,其已成为制备碳材料的理想生物质原料[28]。
本研究以甘蔗渣合成的碳量子点作为荧光信号,以核酸适配体作为识别元素,采用EDC/NHS活化法将氨基标记的E2核酸适配体连接到碳量子点表面,构建了一种新型荧光探针,用于水环境中雌二醇的灵敏、快速、特异性检测,并对实际水样进行分析探讨,旨在为基于核酸适配体修饰的碳量子点荧光探针对水体中污染物的检测机理、痕量污染物的高灵敏和特异性检测提供理论依据和技术支持。
基于甘蔗渣衍生碳量子点的荧光适配体探针的制备及其对17β-雌二醇的检测效果
Preparation of fluorescent aptamer probe based on bagasse derived carbon quantum dots and its detection effect on 17β-estradiol
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摘要: 为实现灵敏、快速、特异性地检测水环境中的17β-雌二醇 (E2) ,以甘蔗渣衍生的碳量子点作为荧光信号,核酸适配体 (aptamer) 作为识别元素,构建了一种可以特异性检测E2的荧光探针,通过荧光强度的变化来定量检测E2并对检测效果进行分析。结果表明:核酸适配体能成功修饰在碳量子点的表面形成稳定的荧光探针;200 mg·L−1的碳量子点与1 μmol·L−1的aptamer为荧光探针的最佳构建比例;相对荧光强度与0~10 μg·L−1质量浓度的雌二醇成正比,且最低检测限为0.42 μg·L−1;该荧光探针可成功应用于水体中E2的检测,回收率为93.6%~106.5%。与传统的仪器检测方法相比,该荧光探针检测E2具有良好的选择性和重现性,还具有操作简单、成本低的优点。本研究成果可为核酸适配体构建的荧光探针在水环境检测中的推广应用提供参考。Abstract: In order to realize the sensitive, rapid and specific detection of 17β-estradiol in water environment, a fluorescent probe that can specifically detect E2 was built with bagasse derived carbon quantum dots as fluorescence signal and aptamer as recognition element, which could quantitatively detect E2 according to the change of fluorescence intensity, and the detection effect was also analyzed. The results show that the aptamer can successfully modify the surface of carbon quantum dots to form stable fluorescent probes. 200 mg·L−1 carbon quantum dots and 1 μmol·L−1 aptamer was the optimal ratio for fluorescence probe construction. The relative fluorescence intensity was proportional to the mass concentration of estradiol in the range of 0~10 μg·L−1, and the lowest detection limit was 0.42 μg·L−1. The fluorescence probe can be successfully applied to detect E2 in water with a recovery rate of 93.6%~106.5%. Compared with the traditional instrument detection method, the fluorescence probe has good selectivity and reproducibility for E2 detection, as well as the advantages of simple operation and low cost. The results of this study can provide a reference for the popularization and application of fluorescent probes constructed by aptamers in water environment detection.
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Key words:
- bagasse /
- carbon quantum dot /
- aptamer /
- 17β-estradiol /
- fluorescent probe /
- static quenching
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表 1 各种雌二醇检测方法的比较
Table 1. Comparison of various detection methods for E2
表 2 实际水样中E2检测效果(n=3)
Table 2. Detection of E2 in real water samples (n=3)
样品来源 加入的E2质量浓度/(μg·L−1) 检测的E2质量浓度/(μg·L−1) 回收率/% 相对标准偏差/% 自来水 5 4.75 95.0 3.13 8 8.22 102.8 2.81 10 10.39 103.9 3.75 湖水 5 4.68 93.6 2.35 8 8.52 106.5 2.69 10 10.26 102.6 3.84 -
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