Photo-genosensor for Trichomonas vaginalis based on gold nanoparticles-genomic DNA.

Trichomoniasis, an infectious disease caused by a parasite called Trichomonas vaginalis (T. vaginalis), enhances the risk of HIV infection, cervical and prostate cancer, and infertility. Therefore, efforts have to be made for accurate, specific, and rapid diagnosise and treatment of trichomoniasis. Today, optical nanosensors have created an opportunity for diagnosis without sophisticated and expensive tools and the need for expertise; at the same time, they are highly sensitive and fast. An optical nano-genosensor was designed by conjugation of gold nanoparticles and a specific oligonucleotide (AuNPs-probe) from repeated DNA target for specific and sensitive polymerase chain reaction diagnosis of T. vaginalis gene sequence (L23861.1). The hybridization of AuNPs-probe was investigated with different concentrations of complementary sequence in synthesized target, gene sequence of standard T. vaginalis genomic DNA extraction, and PCR products of genomic DNA samples extracted from patients. Negative samples including synthesized non-complementary sequence, genomics DNA of other pathogens, and genomics DNA of healthy persons were considered for proof of the accuracy of the sensor function. The occurrence of correct hybridization was detected by adding acid to the medium and observing the changes in the color of the medium and spectroscopic spectrum. Based on spectrophotometric results, the fabricated genosensor had detection limits of 35.16 and 31 pg μL-1 for the detection of synthetic target and genomic DNA sequences, respectively. The results confirmed the correct function of genosensor for the detection of T. vaginalis in clinical samples. Advantages such as low cost, visual detection, speed, and easy diagnosis encourage the use of this sensor in pathogen detection in the future.