Construction of a liquid Crystal-based Sensing Platform for the Sensitive Detection of Catalase in Human Serum

Abstract

A briefness, convenient, label-free and sensitive liquid crystal (LC) sensing platform is demonstrated to detect catalase in human serum with the assistance of CeO2 nanomaterials and the single-stranded DNA (ssDNA). In the presence of H2O2 and ssDNA/CeO2 nanomaterials complex, a colourful optical appearance of LCs doped with octadecyl-trimethylammonium bromide (OTAB) was observed under a polarized optical microscopy (POM), which is corresponding to the oblique alignment of LCs at the aqueous-LC interface. This can be ascribed to the disruption of the OTAB monolayers by ssDNA that is set free from the surface of CeO2 nanomaterials in the presence of H2O2. The stronger coordination interaction between H2O2 and CeO2 nanomaterials causes a replacement for ssDNA. Interestingly, with the hydrolysis of H2O2 by catalase, the LCs exhibit a dim image, which suggests the upright alignment of LCs at the aqueous-LC interface. It is because there is no free ssDNA discharged into the aqueous solution after the hydrolysis of H2O2. Hence, by observing the changes of colourful and dim optical images of LCs, catalase can be analyzed with remarkable sensitivity and excellent specificity. The detection limit of catalase reaches as low as ∼ 1 mU/mL. Besides, the detection of catalase in human serum is also successfully achieved, which makes this assay meets the requirement of practical applications. Therefore, this work offers an effective and appealing strategy for the real-time and label-free detection of catalase in human serum.