Abstract

A portable microfluidic device with highly sensitive enzyme nanoprobe (Fe₃O₄ MNPs–urease, average size 34.6 nm) was demonstrated for the analysis of heavy metals ions (Hg²⁺, Cd²⁺ and Pb²⁺) in fish gill and muscle tissue. The immobilized urease nanoprobe (K_m = 0.05 mM) exhibited twofold sensitivity over the free enzyme assay (apparent K_m = 0.1 mM). The nanoprobe was characterized using SEM, EDAX, PSA and FT-IR. The inhibition measurements were carried out for individual as well as the mixture of metal ions (CRM standards of 9 elements (CRM_mix-9)). The lower limit of quantification (LOQ) (0.5, 0.1, and 0.1 ng L⁻¹ for Hg²⁺, Cd²⁺, and Pb²⁺) and lower limit of detection (LOD) was achieved at 0.1 ng L⁻¹ with sensitivity 8–14% per decade for Hg²⁺, Cd²⁺, and Pb²⁺ ions. A visual result can be observed by the naked eye through the microfluidic device as well as with 96 transparent microwell plates. The order of relative inhibition was found to be CRM_mix-9 > (Hg²⁺ + Cd²⁺ + Pb²⁺) > (Cd²⁺ + Pb²⁺) > (Pb²⁺ + Hg²⁺) > (Hg²⁺ + Cd²⁺) > Pb²⁺ > Cd²⁺ > Hg²⁺, respectively. The recovery % in fish tissues were found to be 88–98% for Hg²⁺, Cd²⁺ and Pb²⁺ ions.

摘要

展示了具有高灵敏度酶纳米探针（Fe ₃ O ₄ MNPs-脲酶，平均粒径34.6 nm）的便携式微流控设备，用于分析鱼g和肌肉中的重金属离子（Hg 2 ⁺，Cd ²⁺和Pb ²⁺）组织。固定化脲酶纳米探针（K _m = 0.05 mM）相对于游离酶分析（表观K _m = 0.1 mM）表现出两倍的敏感性。使用SEM，EDAX，PSA和FT-IR对纳米探针进行了表征。对单独的以及金属离子的混合物（9种元素的CRM标准（CRM _{mix- 9}））。定量下限（LOQ）（对于Hg 2 ⁺，Cd ²⁺和Pb ^2+分别为0.5、0.1和0.1 ng L ^-1）和检测下限（LOD）在0.1 ng L ^-1下达到对Hg 2 ⁺，Cd ²⁺和Pb ²⁺离子的灵敏度为每十年8-14％。肉眼可通过微流体装置以及96个透明微孔板观察到视觉结果。相对抑制的顺序被发现是CRM _{mix- 9} >（汞²⁺ +镉²⁺ + PB ²⁺）>（CD ²⁺ + PB ²⁺）>（铅²⁺+ Hg 2 ⁺）>（Hg ²⁺ + Cd 2 ⁺）> Pb ²⁺ > Cd ²⁺ > Hg ²⁺。发现鱼组织中Hg 2 ⁺，Cd ²⁺和Pb ²⁺离子的回收百分比为88–98％。