Carbon nanodots based biosensors for gene mutation detection

•Carbon nanodots (CDs) modified disposable electrodes.•Electrochemical DNA biosensor based on carbon nanodots (CDs).•Disposable biosensor for gene mutation detection in real PCR samples. An electrochemical DNA biosensor based on a carbon nanodots (CDs) modified screen-printed gold electrode as a transducer is reported in this work. CDs were synthesized by thermal carbonization of ethyleneglycol bis-(2-aminoethylether)-N,N,N’,N’-tetraacetic acid (EGTA) and characterized by different techniques (DLS, TEM, FTIR, Raman). The electrode surface modification was accomplished by drop-casting a suspension of CDs. SEM analysis and cyclic voltammetry were used to characterize the resulting modified electrode. Synthetic 25-mer or 100-mer DNA capture probes, capable to hybridize with a specific sequence of the pathogen Helicobacter pylori or the cystic fibrosis transmembrane regulator (CFTR) gene were attached to the CDs-gold surface. A 25-bases synthetic fully complementary sequence or a single nucleotide polymorphism to the DNA capture probe and a 373-bases PCR amplicon of exon 11 of CFTR containing a sequence complementary to the capture probe, were employed as target. The hybridization event was electrochemically monitored by using safranine as redox indicator, which selectively binds to double stranded DNA (dsDNA). A detection limit of 0.16nM was obtained for the 25-mer synthetic target DNA. The biosensor shows a very high reproducibility and selectivity, allowing to detect a single nucleotide polymorphism. It has been applied to the detection of F508del mutation in the CFTR gene.