Abstract In the broad research of the GMR bio-sensing technology, it is vital to explore appropriate magnetic labels and its influences on the detection signal. In this work, four kinds of ferrite particles of γ-Fe2O3, CoFe2O4, NiFe2O4 and NiZnFe2O4 were prepared through calcining the Dimethyl Formamide (DMF) solution of the transition metal nitrates [Fe(NO3)3 and X(NO3)2, X = Co, Ni, Zn] to study the effect of magnetic properties on detection signals using a DC in-plane measuring method. It was revealed that for four particles, the output voltage differences |ΔV| between with and without magnetic particles exhibit log-linear functions of the particles concentrations x in the range from 0.1 to 10 ng/mL. A very low limitation of detection (LOD) of 0.1 ng/mL for all the samples was obtained, which is two orders smaller than that in the previous work. Moreover, the change of output voltage difference at the LOD (|ΔVlim|) is proportional to the magnetization at bias field (bias magnetization, Mbias), which indicates that larger Mbias leads to a lower LOD. This work provides a useful guidance in selecting or preparing magnetic labels to enhance the sensitivity of GMR biosensors.

中文翻译：

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纳米颗粒偏磁对超低浓度检测GMR传感器信号和灵敏度的影响

摘要 在GMR生物传感技术的广泛研究中，探索合适的磁性标记及其对检测信号的影响至关重要。在这项工作中，通过煅烧过渡金属硝酸盐 [Fe(NO3)3 和 X(NO3)2 的二甲基甲酰胺 (DMF) 溶液，制备了 γ-Fe2O3、CoFe2O4、NiFe2O4 和 NiZnFe2O4 四种铁氧体颗粒，X = Co, Ni, Zn] 使用直流面内测量方法研究磁性对检测信号的影响。结果表明，对于四个粒子，输出电压差|ΔV| 有和没有磁性颗粒之间的颗粒浓度 x 的对数线性函数在 0.1 到 10 ng/mL 的范围内。所有样品的检测限 (LOD) 为 0.1 ng/mL，比之前的工作小两个数量级。此外，LOD 处输出电压差的变化 (|ΔVlim|) 与偏置场的磁化强度 (bias Magnetization, Mbias) 成正比，这表明 Mbias 越大，LOD 越低。这项工作为选择或制备磁性标签以提高 GMR 生物传感器的灵敏度提供了有用的指导。