Moyo Mambo, Okonkwo Jonathan O, Agyei Nana M
Department of Environmental, Water, and Earth Sciences, Tshwane University of Technology, 175 Nelson Mandela Drive, Arcadia Campus, Pretoria 0001, South Africa.
Department of Environmental, Water, and Earth Sciences, Tshwane University of Technology, 175 Nelson Mandela Drive, Arcadia Campus, Pretoria 0001, South Africa.
Enzyme Microb Technol. 2014 Mar 5;56:28-34. doi: 10.1016/j.enzmictec.2013.12.014. Epub 2013 Dec 25.
A biosensor for trace metal ions based on horseradish peroxidase (HRP) immobilized on maize tassel-multiwalled carbon nanotube (MT-MWCNT) through electrostatic interactions is described herein. The biosensor was characterized using Fourier transform infrared (FTIR), UV-vis spectrometry, voltammetric and amperometric methods. The FTIR and UV-vis results inferred that HRP was not denatured during its immobilization on MT-MWCNT composite. The biosensing principle was based on the determination of the cathodic responses of the immobilized HRP to H₂O₂, before and after incubation in trace metal standard solutions. Under optimum conditions, the inhibition rates of trace metals were proportional to their concentrations in the range of 0.092-0.55 mg L⁻¹, 0.068-2 mg L⁻¹ for Pb²⁺ and Cu²⁺ respectively. The limits of detection were 2.5 μg L⁻¹ for Pb²⁺ and 4.2 μg L⁻¹ for Cu²⁺. Representative Dixon and Cornish-Bowden plots were used to deduce the mode of inhibition induced by the trace metal ions. The inhibition was reversible and mixed for both metal ions. Furthermore, the biosensor showed good stability, selectivity, repeatability and reproducibility.
本文描述了一种基于辣根过氧化物酶（HRP）通过静电相互作用固定在玉米须-多壁碳纳米管（MT-MWCNT）上的痕量金属离子生物传感器。采用傅里叶变换红外光谱（FTIR）、紫外可见光谱、伏安法和安培法对该生物传感器进行了表征。FTIR和紫外可见光谱结果表明，HRP固定在MT-MWCNT复合材料上的过程中未发生变性。生物传感原理基于在痕量金属标准溶液中孵育前后，测定固定化HRP对H₂O₂的阴极响应。在最佳条件下，痕量金属的抑制率与它们的浓度成正比，Pb²⁺和Cu²⁺的浓度范围分别为0.092 - 0.55 mg L⁻¹和0.068 - 2 mg L⁻¹。Pb²⁺的检测限为2.5 μg L⁻¹，Cu²⁺的检测限为4.2 μg L⁻¹。使用代表性的迪克森（Dixon）和康沃尔-鲍登（Cornish-Bowden）图来推断痕量金属离子诱导的抑制模式。两种金属离子的抑制都是可逆的且为混合型。此外，该生物传感器表现出良好的稳定性、选择性、重复性和再现性。
