Microchimica Acta ( IF 5.3 ) Pub Date : 2024-05-11 , DOI: 10.1007/s00604-024-06382-5 Shikha Jain 1 , Monika Nehra 2 , Rajesh Kumar 2 , Neeraj Dilbaghi 1 , Ki-Hyun Kim 3 , Sandeep Kumar 1, 4
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A robust “on–off” fluorescent aptasensor was developed using nanohybrids of molybdenum sulfide (MoS2) quantum dot (QD)–doped zinc metal–organic frameworks (Zn-MOF) for selective and sensitive detection of cadmium ions (Cd2+) in water. This nanohybrid (MoS2@Zn-MOF), synthesized via “bottle around the ship” methodology, exhibited a high-intensity fluorescence emission centered at 430 nm (λEm) (blue) on excitation at 320 nm (λEx). Further, the conjugation of this fluorophore to phosphate-modified cadmium aptamer (Cd-2–2) was achieved through carbodiimide reaction. The hybridization of prepared sensing probe (MoS2@Zn-MOF/Cd-2–2 aptamer) was done with dabcyl-conjugated complementary DNA (cDNA), acting as energy donor–acceptor pair in the fluorescence resonance energy transfer (FRET) system. This hybridization causes the fluorescence quenching of the nanohybrid. In the presence of Cd2+, the aptamer from the fabricated nano-biosensing probe binds to these ions, resulting in release of dabcyl-cDNA oligomer. This release of dabcyl-cDNA oligomer from the sensing probes restores the fluorescence of the nanohybrid. Under optimized conditions (sensing probe/dabcyl-cDNA ratio 1/7, pH 7.4, and temp 28 °C), the sensing probe showed a fast response time of 1 min. The fluorescence intensity of the nanohybrid can be utilized to determine the concentration of Cd2+. The proposed aptasensor achieved highly sensitive detection of Cd2+ with a limit of detection (LOD) of 0.24 ppb over the range of 1 × 10−9 to 1 × 10−4 M along with minimal effects of interferences (e.g., Hg2+, Pb2+, and Zn2+) and good reproducibility. The designed aptasensor based on MoS2@Zn-MOF nanofluorophore offers a highly sensitive and selective approach for rapid screening of metal ions in aqueous environments.
Graphical Abstract
中文翻译：
开发基于MoS2掺杂Zn-MOF作为发光体的FRET适体传感器，用于选择性检测水溶液中的镉
使用硫化钼 (MoS 2 ) 量子点 (QD) 掺杂锌金属有机框架 (Zn-MOF) 纳米混合物开发了一种强大的“开关”荧光适体传感器，用于选择性和灵敏地检测镉离子 (Cd 2+ )在水中。这种纳米杂化物 (MoS 2 @Zn-MOF) 通过“瓶绕船”方法合成，在 320 nm ( λ Ex ) 激发下表现出以 430 nm ( λ Em )（蓝色）为中心的高强度荧光发射。此外，该荧光团与磷酸盐修饰的镉适体（Cd-2-2）的结合是通过碳二亚胺反应实现的。制备的传感探针（MoS 2 @Zn-MOF/Cd-2–2 适体）与 dabcyl 缀合的互补 DNA (cDNA) 进行杂交，在荧光共振能量转移 (FRET) 系统中充当能量供体-受体对。这种杂交导致纳米杂化物的荧光猝灭。在 Cd 2+存在的情况下，所制造的纳米生物传感探针的适体与这些离子结合，导致 dabcyl-cDNA 寡聚物的释放。 dabcyl-cDNA 寡聚物从传感探针中的释放恢复了纳米杂化物的荧光。在优化条件下（传感探针/dabcyl-cDNA比例1/7、pH 7.4、温度28℃），传感探针表现出1分钟的快速响应时间。纳米混合物的荧光强度可用于确定Cd 2+的浓度。所提出的适体传感器在 1 × 10 -9至 1 × 10 -4 M 范围内实现了 Cd 2+的高灵敏度检测，检测限 (LOD) 为 0.24 ppb，并且干扰影响最小（例如、Hg 2+ 、Pb 2+和Zn 2+ ）且重现性良好。基于MoS 2 @Zn-MOF纳米荧光团设计的适体传感器为快速筛选水环境中的金属离子提供了一种高度灵敏和选择性的方法。
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