A chemiluminescence biosensor for lysozyme detection based on aptamers and hemin/G-quadruplex DNAzyme modified sandwich-rod carbon fiber composite

In our work, aptamers and hemin/G-quadruplex DNAzyme modified sandwich -rod graphene quantum dots @ graphene oxide @ carbon fiber composite (DNAzyme/L-Apt/GQDs@GO@CF) was successfully prepared for sensitive and selective chemiluminescence (CL) detection of lysozyme (LZM). Initially, GQDs@GO@CF was successfully prepared and characterized. Lysozyme aptamers (L-Apt) as a recognition element and hemin/Gquadruplex DNAzyme (DNAzyme) as a catalyst of luminal - H2O2 were modified on the surface of GQDs@GO@CF, sequentially. The immobilization properties of GQDs@GO@CF to L-Apt and the adsorption properties of L-Apt/GQDs@GO@CF to DNAzyme were also researched, respectively. Then, the modified sandwich-rod carbon fiber composite was applied to the construction of CL biosensor for LZM detection. When LZM existed, DNAzyme would be released from the surface of L-Apt/GQDs@GO@CF and catalyzed the reaction of luminal - H2O2. Under optimized conditions, the CL biosensor for LZM detection showed wide linear range of 2.64 x 10(-10) to 6.6 x 10(-8) g/L and low detection limit of 1.25 x 10(-11) g/L (3 delta). Finally, the CL biosensor was successfully used for LZM detection in human urine samples and illustrated the potential application in pratical samples.