A label-free, PCR-free and signal-on electrochemical DNA biosensor for Leishmania major based on gold nanoleaves.

Detection of leishmaniasis is important in clinical diagnoses. In the present study, identification of Leishmania parasites was performed by a label-free, PCR-free and signal-on ultrasensitive electrochemical DNA biosensor. Gold nanoleaves were firstly electrodeposited by an electrodeposition method using spermidine as a shape directing agent. The biosensor was fabricated by immobilization of a Leishmania major specific DNA probe onto gold nanoleaves, and methylene blue was employed as a marker. Hybridization of the complementary single stranded DNA sequence with the biosensor under the selected conditions was then investigated. The biosensor could detect a synthetic DNA target in a range of 1.0×10-10 to 1.0×10-19molL-1 with a limit of detection of 1.8×10-20molL-1, and genomic DNA in a range of 0.5-20ngμL-1 with a limit of detection of 0.07ngμL-1. The biosensor could distinguish Leishmania major from a non-complementary-sequence oligonucleotide and the tropica species with a high selectivity. The biosensor was applicable to detect Leishmania major in patient samples.