Usefulness of magnetically-controlled MNPs-enzymes microreactors for the fluorimetric determination of total cholesterol in serum

• Published in: Talanta (Oxford) Vol. 208; p. 120426
• Main Authors: Román-Pizarro, Vanesa, Ramírez-Gutiérrez, Manuel, Gómez-Hens, Agustina, Fernández-Romero, Juan Manuel
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-02-2020
• Subjects: Cholesterol; Electromagnet retention; Enzyme magnetic nanoparticles; Fluorimetric; Naphtofluorescein; Serum; Serum; Fluorimetric; Naphtofluorescein; Electromagnet retention; Enzyme magnetic nanoparticles; Cholesterol
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2019.120426

A new dynamic method containing a magnetically retained enzyme reactor (MRER) located in the reaction/detection zone of a flow injection (FI) system, has been used for the determination of total cholesterol in serum samples. The MRER was formed by a mixture ratio of 2/1 of immobilized enzymes cholesterol esterase (ChE) and cholesterol oxidase (COx) on magnetic nanoparticles (MNPs). The analytical signal is based on the fluorescence decreasing of the fluorophore naphtofluorescein (NF) due to its oxidation by the H2O2 formed in the enzymatic reactions. The dynamic range of the calibration graph was 1.55–100 mmol L−1 expressed as total cholesterol concentration (r2 = 0.9995, n = 5, r = 3), and the detection limit was 0.65 mmol L−1. The precision expressed as relative standard deviation (RSD %) was in the range of 4.7 and 0.6%. The method showed a sampling frequency of 10 h−1 and this method was applied to the determination of cholesterol in serum samples. The results were compared with those obtained using a previous automated clinical analyzer (ILab 600 analyzer). Also, recovery values ranging between 88.5 and 101.5% were achieved.
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•ChE and COx were successfully immobilized onto MNPs.•The reduced size MRER on the reaction/detection zone was beneficial in reducing enzymes requirement and cost reduction assay.•The results confirm the efficiency of the MRER configuration in the applied dynamic microsystems.