One-step electrochemical detection of cholesterol in the presence of suitable K3Fe(CN)6/phosphate buffer mediator by an electrochemical approach

• One-step ChOx immobilization in fabricated on AuE/SAM coupled onto micro-chips.
• The cholesterol biosensor exhibits higher sensitivity and lower detection limit.
• A large group of selective cholesterol enzyme displays a wide range of biomedical applications.

One-step approach of cholesterol biosensor was fabricated onto smart micro-chips based on cholesterol oxidase (ChOx) co-immobilized thioglycolic acid self-assembled monolayer (TGA-SAM) for biomedical applications. The selective cholesterol biosensor was investigated with modified tiny micro-chip (Au/SAM/ChOx) by the facile and reliable cyclic voltammetric (CV) method in a K3Fe(CN)6/phosphate buffer (PB) system. The modified micro-chip displayed a large dynamic range (1.0 nmol L−1 to 1.0 mmol L−1), lower detection limit (~0.49 nmol L−1, based on S/N~3), higher sensitivity (~93.75 µA µmol L−2 cm−2), good linearity (correlation coefficient r2, 0.9995), lower sample volume (<50.0 μL), and good stability as well as reproducibility. The Au/TGA system was implemented for a facile and simple approach to the immobilization of ChOx onto micro-chip, which can offer analytical access to a large group of enzymes for a wide range of bio-molecule applications in health-care and biomedical fields. This integrated microchip provides a promising low-cost platform for the sensitive and rapid detection of biomolecules using miniatured samples.

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