Helicobacter pylori is known as type 1 carcinogen and the main cause of gastritis, stomach ulcers and gastric cancer. H. pylori infection is primarily diagnosed by the conventional methods. However, due to the importance of early-phase diagnosis of H. pylori, we developed a non-crosslinking gold nanoprobe method based on the aggregation of nanoparticles for the direct detection of the target.

: A specific target region in the genomic DNA of H. pylori was selected, and a complementary thiolate probe was designed. The probe was used to functionalize gold nanoparticles. The genomic DNA content of the samples was accessed by the boiling method. The nucleic acid content of the cells was used for the further detection procedure. After a single denaturation and annealing stage, magnesium chloride was used for the induction stage in the colorimetric assay.

The results show that the designed Au-nanoprobe could attach specifically to the target region among ten different bacteria, providing a specific colorimetric detection approach in less than six minutes. Furthermore, the optimized concentration of the salt yielded an optimum color differentiation between the positive and negative samples. In positive samples, the nanoparticles stayed dispersed (red) due to a successful hybridization and increased charge density while in negative samples, aggregation occurred due to the absence of a complementary sequence resulting in a blue shift.

: The direct gold nanoprobe-based method could be employed as a simple, rapid, and affordable method to nano-diagnosis of H. pylori and help to restrain the spread of H. pylori infection