Centre of Applied Science for Health (CASH), Technological University Dublin, Tallaght Campus, Dublin 24, Ireland.
Dundalk Institute of Technology, Dundalk, Co., Louth, Ireland.
Mikrochim Acta. 2020 Mar 13;187(4):225. doi: 10.1007/s00604-020-4203-1.
Synthesis and functionalization of magnetite nanoparticles (FeO) was achieved with the view to covalently bind both cholesterol oxidase and cholesterol esterase biorecognition agents for the development of free and total cholesterol biosensors. Prior to enzyme attachment, FeO was functionalized with 3-aminopropyltriethoxysilane (APTES) and polyamidoamine (PAMAM) dendrimer. Characterization of the material was performed by FT-IR and UV spectroscopy, SEM/EDX surface analysis and electrochemical investigations. The response to cholesterol and its palmitate ester was examined using cyclic voltammetry. Optimum analytical performance for the free cholesterol biosensor was obtained using APTES-functionalized magnetite with a sensitivity of 101.9 μA mM cm, linear range 0.1-1 mM and LOD of 80 μM when operated at 37 °C. In the case of the total cholesterol biosensor, the best analytical performance was obtained using PAMAM dendrimer-modified magnetite with sensitivity of 73.88 μA mM cm and linear range 0.1-1.5 mM, with LOD of 90 μM. A stability study indicated that the free cholesterol biosensors retained average activity of 98% after 25 days while the total cholesterol biosensors retained 85% activity upon storage over the same period. Graphical abstract Schematic representation of cholesterol esterase and oxidase loaded magnetic nanoparticles (FeO@APTES or FeO@APTES-PAMAM) generating hydrogen peroxide from cholesterol palmitate.
磁性纳米粒子（FeO）的合成和功能化旨在通过共价键合胆固醇氧化酶和胆固醇酯酶生物识别剂，用于开发游离和总胆固醇生物传感器。在酶附着之前，FeO 用 3-氨丙基三乙氧基硅烷（APTES）和聚酰胺胺（PAMAM）树枝状大分子进行功能化。通过傅里叶变换红外光谱（FT-IR）和紫外光谱、SEM/EDX 表面分析和电化学研究对材料进行了表征。使用循环伏安法检查了对胆固醇及其棕榈酸酯的响应。使用 APTES 功能化的磁铁矿获得了游离胆固醇生物传感器的最佳分析性能，其灵敏度为 101.9 μA mM cm，线性范围为 0.1-1 mM，LOD 为 80 μM，在 37°C 下工作。对于总胆固醇生物传感器，使用 PAMAM 树枝状大分子修饰的磁铁矿获得了最佳的分析性能，灵敏度为 73.88 μA mM cm，线性范围为 0.1-1.5 mM，LOD 为 90 μM。稳定性研究表明，游离胆固醇生物传感器在 25 天后保留了平均 98%的活性，而总胆固醇生物传感器在同一时期储存后保留了 85%的活性。
