(Nanowerk Highlights) Advanced molecular diagnostic tests that can quickly and precisely detect disease in the home could revolutionize preventive medicine and improve global biosecurity. Nucleic acid amplification tests (NAAT) such as polymerase chain reaction (PCR) provide high sensitivity and specificity for the identification of infectious diseases by amplifying the DNA and RNA of pathogens.
However, centralized laboratory-based NAAT requires complex and tedious sample processing steps such as pathogen lysis, nucleic acid purification and enzymatic amplification. These manual procedures rely on trained personnel operating expensive equipment, limiting accessibility.
An integrated microfluidic platform that combines automated sample preparation with on-chip NAAT in one miniature device offers a practical solution for performing precise molecular diagnostics at home without a dedicated laboratory.
Reviews on Advanced Materials (“Towards Fast and Accurate Molecular Diagnostics at Home”) evaluate recent advances in integrated sample preparation for NAAT using common clinical samples such as blood, urine, saliva, and faeces.
Blood provides many genetic and infectious disease biomarkers. However, invasive sampling via venipuncture or fingerprick is required to obtain blood. The integrated microcapillary loop-mediated isothermal amplification (LAMP) method successfully extracts DNA from a small 200 nL blood sample obtained with a minimally invasive finger prick, avoiding the need for expensive and painful traditional blood draws.
Urine offers a completely noninvasive liquid biopsy, in contrast to blood. However, urine contains much lower levels of nucleic acid biomarkers. Therefore, a microfluidic magnetic bead platform is required to capture and concentrate rare pathogenic DNA/RNA from large volumes of urine prior to extraction. Concentration increases the detection limit.
Saliva and nasal swabs allow non-invasive sampling of respiratory infections by means of viral particles secreted in mucus. The integrated microfluidic cartridge extracts HIV ribonucleic acid (RNA) biomarkers from as little as 30 μL of saliva in just 10 minutes, demonstrating the potential for extremely fast and sensitive sample-to-answer NAAT.
Stools contain gastrointestinal pathogens and can noninvasively identify lower gastrointestinal infections. However, viscous faecal samples require mechanical homogenization of the chip prior to pathogen capture and nucleic acid extraction.
Recently, an ingenious sharp-end acoustofluidic system actively homogenizes the feces inside the micro-ducts by generating strong flow forces with ultrasonically oscillating microscopic structures fabricated from silicon.
The integrated reusable microfluidic chip flexibly processes a wide variety of clinical sample types on a common platform:
The microfluidic channel is packed with silica microbeads which extract purified RNA from raw cellular lysates prior to on-chip detection of nucleic acid sequence (NASBA) based amplification without cross-contamination between samples.
The self-integrated blood analysis chip successfully integrates plasma separation from small 5–10 µL blood specimens with a downstream multiplex immunoassay that detects protein biomarkers.
The modular microfluidic platform allows for interchangeable single-use testing cartridges customized for specific sample types such as sputum or blood, providing a versatile tool for a wide range of nucleic acid and protein diagnostic assays.
On-chip NAAT offers many advantages over conventional benchtop laboratory testing methods:
In-house NAAT paired with automated integrated microfluidic sample preparation could enable frequent population screening during viral outbreaks, providing invaluable epidemiological data to stop disease in its tracks. Their comfort and accessibility in low resource settings is critical to improving preventive medicine on a global scale. In the not too distant future, wearable flexible microfluidic biosensors could provide on-site molecular diagnostic capabilities using easily accessible microliter volumes of body fluids such as sweat or saliva.
In short, the innovative lab-free microfluidic NAAT platform brings the powerful capabilities of advanced nucleic acid testing right into the home, workplace, or even the pocket of the average consumer to provide on-demand decentralized diagnostics that can help stop outbreaks before they happen. to spread.
– Michael is the author of three books by the Royal Society of Chemistry:
Nano-Society: Pushing the Boundaries of Technology,
Nanotechnology: A Small Future And
Nanoengineering: Skills and Tools for Making Technology Invisible
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