A nano-porous CeO(2)/Chitosan composite film as the immobilization matrix for colorectal cancer DNA sequence-selective electrochemical biosensor

CeO₂/Chitosan (CHIT) composite matrix was firstly developed for the single-stranded DNA (ssDNA) probe immobilization and the fabrication of DNA biosensor related to the colorectal cancer gene. Such matrix combined the advantages of CeO₂ and chitosan, with good biocompatibility, nontoxicity and excellent electronic conductivity, showing the enhanced loading of ssDNA probe on the surface of electrode. The preparation method is quite simple and inexpensive. The hybridization detection was accomplished by using methylene blue (MB), an electroactive lable, as the indicator. The differential pulse voltammetry (DPV) was employed to record the signal response of MB and determine the amount of colorectal cancer target DNA sequence. The experimental conditions were optimized. The established biosensor has high detection sensitivity, a relatively wide linear range from 1.59 × 10⁻¹¹ to 1.16 × 10⁻⁷ mol L⁻¹ and the ability to discriminate completely complementary target sequence and four-base-mismatched sequence.