In the present study, an innovative and simple electrochemical magneto biosensor based on carboxyethylsilanetriol-modified iron oxide (Fe₃O₄) magnetic nanoparticles was designed for ultrasensitive and specific analysis of cotinine, an important marker of smoking. Anticotinine antibodies were covalently immobilized on carboxylic acid-modified magnetic nanoparticles, and the cotinine-specific magnetic nanoparticles created a specific surface on the working electrode surface. The use of magnetic nanoparticles as an immobilization platform for antibodies provided a large surface area for antibody attachment and increased sensitivity. In addition, the advantages of the new immobilization platform were reusing the working electrode numerous times, recording repeatable and reproducible signals, and reducing the necessary volume of biomolecules. The specific interaction between cotinine and cotinine-specific antibody-attached magnetic nanoparticles restricted the electron transfer of the redox probe and changed the impedimetric response of the electrode correlated to the concentration of cotinine. The magneto biosensor had a wide detection range (2–300 pg/mL), a low LOD (606 fg/mL), and an acceptable recovery (97.24–105.31%) in real samples. In addition, the current biosensor’s measurement results were in good agreement with those found by the standard liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA) methods. These results showed that a simple impedimetric immunosensing platform was generated for the cotinine analysis.

中文翻译：

---

羧乙基硅烷三醇包被的磁性纳米颗粒作为可替宁电化学磁传感的超灵敏免疫平台

在本研究中，设计了一种基于羧乙基硅烷三醇修饰的氧化铁（Fe ₃ O ₄）磁性纳米粒子的创新且简单的电化学磁生物传感器，用于对可替宁（吸烟的重要标志物）进行超灵敏和特异性分析。抗可替宁抗体共价固定在羧酸修饰的磁性纳米粒子上，可替宁特异性磁性纳米粒子在工作电极表面上形成特定表面。使用磁性纳米粒子作为抗体的固定平台为抗体附着提供了大的表面积并提高了灵敏度。此外，新固定平台的优点是可以多次重复使用工作电极，记录可重复和可再现的信号，并减少所需的生物分子体积。可替宁和可替宁特异性抗体附着的磁性纳米颗粒之间的特异性相互作用限制了氧化还原探针的电子转移，并改变了与可替宁浓度相关的电极的阻抗响应。磁生物传感器在实际样品中具有较宽的检测范围 (2–300 pg/mL)、低 LOD (606 fg/mL) 和可接受的回收率 (97.24–105.31%)。此外，当前生物传感器的测量结果与标准液相色谱（HPLC）和酶联免疫吸附测定（ELISA）方法发现的结果非常吻合。这些结果表明，为可替宁分析生成了一个简单的阻抗免疫传感平台。