Colorimetric-based detection of Ureaplasma urealyticum using gold nanoparticles

Ureaplasma infections: update on epidemiology, antimicrobial resistance, and pathogenesis

Human Ureaplasma species are being increasingly recognized as opportunistic pathogens in human genitourinary tract infections, infertility, adverse pregnancy, neonatal morbidities, and other adult invasive infections. Although some general reviews have focused on the detection and clinical manifestations of Ureaplasma spp., the molecular epidemiology, antimicrobial resistance, and pathogenesis of Ureaplasma spp. have not been adequately explained. The purpose of this review is to offer valuable insights into the current understanding and future research perspectives of the molecular epidemiology, antimicrobial resistance, and pathogenesis of human Ureaplasma infections. This review summarizes the conventional culture and detection methods and the latest molecular identification technologies for Ureaplasma spp. We also reviewed the global prevalence and mechanisms of antibiotic resistance for Ureaplasma spp. Aside from regular antibiotics, novel antibiotics with outstanding in vitro antimicrobial activity against Ureaplasma spp. are described. Furthermore, we discussed the pathogenic mechanisms of Ureaplasma spp., including adhesion, proinflammatory effects, cytotoxicity, and immune escape effects, from the perspectives of pathology, related molecules, and genetics.

SARS-CoV-2 detection by targeting four loci of viral genome using graphene oxide and gold nanoparticle DNA biosensor

The current COVID-19 pandemic outbreak poses a serious threat to public health, demonstrating the critical need for the development of effective and reproducible detection tests. Since the RT-qPCR primers are highly specific and can only be designed based on the known sequence, mutation sensitivity is its limitation. Moreover, the mutations in the severe acute respiratory syndrome β-coronavirus (SARS-CoV-2) genome led to new highly transmissible variants such as Delta and Omicron variants. In the case of mutation, RT-qPCR primers cannot recognize and attach to the target sequence. This research presents an accurate dual-platform DNA biosensor based on the colorimetric assay of gold nanoparticles and the surface-enhanced Raman scattering (SERS) technique. It simultaneously targets four different regions of the viral genome for detection of SARS-CoV-2 and its new variants prior to any sequencing. Hence, in the case of mutation in one of the target sequences, the other three probes could detect the SARS-CoV-2 genome. The method is based on visible biosensor color shift and a locally enhanced electromagnetic field and significantly amplified SERS signal due to the proximity of Sulfo-Cyanine 3 (Cy3) and AuNPs intensity peak at 1468 cm-1. The dual-platform DNA/GO/AuNP biosensor exhibits high sensitivity toward the viral genome with a LOD of 0.16 ng/µL. This is a safe point-of-care, naked-eye, equipment-free, and rapid (10 min) detection biosensor for diagnosing COVID-19 cases at home using a nasopharyngeal sample.

Design of a gold nanoprobe for the detection of Pseudomonas aeruginosa elastase gene (lasB)

In this study, a gold nanoparticle-based DNA diagnostic sensor that is sensitive to the aggregation states of gold nanoparticles was used to identify the amplified and non-amplified lasB gene.