Molecularly imprinted sensor based on cascade enzyme system supported by metal-organic framework (UiO-66-NH2) for sensitive colorimetric detection of cholesterol

Cholesterol is a crucial cellular molecule in the human body, and a neutral lipid necessary for maintaining the integrity and fluidity of cell membranes. Additionally, it acts as a precursor for the synthesis of essential substances for living organisms, including steroid hormones, bile acids and vitamins. Nonetheless, cholesterol is not always advantageous, and both excess and deficiency of cholesterol can result in serious diseases. Therefore, maintaining cholesterol at a normal level is of paramount importance for the maintenance of normal cellular activity. In this study, an amino-functionalized metal-organic framework (UiO-66-NH2, abbreviated as U6NH2) was used as a carrier, on the surface of which gold nanoparticles (AuNPs) was embedded and cholesterol oxidase (ChOx) was immobilized, and then cholesterol was employed as a template molecule, followed by the synthesis of molecularly imprinted polymers (MIPs). Remarkably, the obtained U6NH2@AuNPs-ChOx@MIPs can be used to facilitate efficacious and selective detection of blood cholesterol through a facile colorimetric method over a range of 2.9 mM - 6.7 mM with a limit of detection (LOD) = 2.4 mM, while the normal level of blood cholesterol should be less than 5.18 mM. Moreover, the sensing system demonstrates excellent stability and satisfactory selectivity. The constructed cholesterol selective detection system reported in this paper is anticipated to have a crucial impact on bioanalysis.