Gold nanoparticles-based biosensing of Leishmania major kDNA genome: Visual and spectrophotometric detections

Precise and sensitive identification methods of Leishmania are required for efficient treatment of leishmaniasis. Detection of Leishmania species approves the efficiency of the applied therapy. Current diagnosis methods, such as culture and microscopy methods, are time-consuming and have limited sensitivity, and are laborious when encountering lots of samples. Although molecular methods can identify Leishmania species, their diagnosis depends on individual responsiveness. Therefore, rapid, sensitive and low-cost methods are required for identification of Leishmania species. In this study, a new method was developed based on hybridization of gold nanoparticles linked a specific single stranded DNA probe from non-protein coding region (AB678349.1) of Leishmania major minicircle kinetoplast DNA (kDNA). Dispersion or aggregation of the gold nanoparticles-probe conjugates in the presence or absence of a complementary DNA sequence leads to an obvious and sensitive change in the UV–vis spectra and the solution color. The results indicated that this method is useful for diagnosis of Leishmania major from other non-Leishmania species with a detection limit of 7.0pgμL−1. The efficacy of the present PCR-free assay was evaluated to identify genomic DNA extracted from Leishmania major and clinical samples.