We use cookies to understand how you use our site and to improve your experience. This includes personalizing content and advertising. To learn more, click here. By continuing to use our site, you accept our use of cookies. Cookie Policy.

Features Partner Sites Information LinkXpress hp
Sign In
Advertise with Us

Download Mobile App




Low-Cost Diagnostic Developed Using Nanostructures

By LabMedica International staff writers
Posted on 25 Oct 2018
The detection of pathogen nucleic acids has broad applications in infection diagnostics and management. More...
Nucleic acid-based human papillomavirus (HPV) testing is essential to contemporary cervical cancer testing. HPV, the most common sexually transmitted infection, is the primary cause of cervical cancer.

A rapid pathogen detection platform has been developed that uses microfluidics containing integrated circuits of DNA nanostructures. The system called enzyme-assisted nanocomplexes for visual identification of nucleic acids, or enVision, has been shown to be capable of room temperature molecular typing of HPV from cervical samples, as well as discovering certain infections that can be undetectable by most standard methods.

Scientists at the National University of Singapore (Singapore) developed the DNA-enzyme nanostructures, which are complexes made of inactivating aptamers linked to Taq DNA polymerase. When complementary target DNA binds an aptamer, the polymerase is released. The freed polymerases then use biotinylated deoxyribonucleotide triphosphates (dNTPs) circulating in the microfluidic cassette to elongate a nearby signaling nanostructure made from a self-priming hairpin molecule.

The biotinylated dNTPs in the signaling structure will also bind streptavidin-horseradish peroxidase (HRP) molecules in the reaction chamber, and in the presence of diaminobenzidine peroxidase the HRP produces a brown precipitate that can be seen with the naked eye or quantified with a smartphone. The system is also modular. Detection reactions take place in an independent microfluidic assay cassette that is preloaded with nanostructures. In order to perform the assay, a test cassette is mounted to a separate cartridge module that is the same for all tests, containing membranes embedded with the universal signaling nanostructures.

The enVision test was also run on a set of 35 clinical endocervical samples in the study and compared to a gold standard test, the Roche Cobas qPCR-based HPV assay. The authors set up enVision to detect HPV 16 and HPV 18 L1 loci in the patient genome, which are the targets of the Roche test. EnVision achieved about 93% sensitivity and 91% specificity for HPV 16, and for HPV 18 the assay showed 83% sensitivity and 100% specificity compared to the Cobas test. Notably, this level of sensitivity and specificity on clinical samples was seen without any pre-amplification, in an equipment-free assay performed at room temperature.

Compared to quantitative polymerase chain reaction (qPCR), enVision showed better sensitivity and fewer false-positive results on a set of synthetic targets representing different subtypes of HPV. The team highlighted that qPCR can be prone to false positives due to non-specific amplification and formation of primer dimers, which, in a clinical setting, can lead to misdiagnoses, wrong or delayed treatments, and patient anxiety and poor health outcomes. The team also compared enVision to a loop-mediated isothermal amplification (LAMP) test and observed that LAMP is prone to primer-dimer formation and false-positive results. The study was originally published online on August 13, 2018, in the journal Nature Communications.

Related Links:
National University of Singapore


New
Gold Member
Hybrid Pipette
SWITCH
Collection and Transport System
PurSafe Plus®
Gram-Negative Blood Culture Assay
LIAISON PLEX Gram-Negative Blood Culture Assay
8-Channel Pipette
SAPPHIRE 20–300 µL
Read the full article by registering today, it's FREE! It's Free!
Register now for FREE to LabMedica.com and get access to news and events that shape the world of Clinical Laboratory Medicine.
  • Free digital version edition of LabMedica International sent by email on regular basis
  • Free print version of LabMedica International magazine (available only outside USA and Canada).
  • Free and unlimited access to back issues of LabMedica International in digital format
  • Free LabMedica International Newsletter sent every week containing the latest news
  • Free breaking news sent via email
  • Free access to Events Calendar
  • Free access to LinkXpress new product services
  • REGISTRATION IS FREE AND EASY!
Click here to Register








Channels

Molecular Diagnostics

view channel
Image: The study shows that periodic ctDNA screening after surgery can help guide a decision to begin adjuvant immunotherapy (Photo courtesy of Adobe Stock)

Blood Test Guides Post-Surgical Immunotherapy for Muscle-Invasive Bladder Cancer

After surgery for muscle-invasive bladder cancer, many patients face uncertainty about whether residual cancer cells remain in their bodies. Now, a new international phase 3 study has demonstrated that... Read more

Hematology

view channel
Image: New evidence shows viscoelastic testing can improve assessment of blood clotting during postpartum hemorrhage (Photo courtesy of 123RF)

Viscoelastic Testing Could Improve Treatment of Maternal Hemorrhage

Postpartum hemorrhage, severe bleeding after childbirth, remains one of the leading causes of maternal mortality worldwide, yet many of these deaths are preventable. Standard care can be hindered by delays... Read more

Immunology

view channel
Image: When assessing the same lung biopsy sample, research shows that only 18% of pathologists will agree on a TCMR diagnosis (Photo courtesy of Thermo Fisher)

Molecular Microscope Diagnostic System Assesses Lung Transplant Rejection

Lung transplant recipients face a significant risk of rejection and often require routine biopsies to monitor graft health, yet assessing the same biopsy sample can be highly inconsistent among pathologists.... Read more
Copyright © 2000-2025 Globetech Media. All rights reserved.