Bi-pseudoenzyme synergetic catalysis to generate a coreactant of peroxydisulfate for an ultrasensitive electrochemiluminescence-based cholesterol biosensor.

A novel electrochemiluminescence (ECL) enzyme biosensor for the ultrasensitive detection of cholesterol was designed based on a bi-pseudoenzymatic reaction to generate a coreactant of peroxydisulfate for signal amplification. In this work, hemin-functionalized graphene (hemin-GR) was synthesized and used to immobilize cholesterol oxidase (COx) to construct an ECL biosensor for cholesterol. When cholesterol was added to the detection solution, COx catalyzed the oxidation of cholesterol to generate H2O2, which could be further catalyzed by hemin to produce O2 as the coreactant in the peroxydisulfate system for signal amplification. The linear range for cholesterol detection was 3.3-1,500 nM, with a lower detection limit of 1.0 nM (signal to noise ratio=3). Therefore, the detection limit and sensitivity of the biosensor were improved. This novel strategy offers advantages of simplicity, improved sensitivity, good selectivity, and repeatability, and therefore, holds promise for use in sensitive bioassays for clinical determination of cholesterol levels.