A team of scientists from University of California Los Angeles and MINATEC innovation campus in Grenoble, France have demonstrated a new imaging technique which could enable larger throughput, lower cost detection of viruses in resource-limited point of care settings.
Particles with a size measured in nanometers are generally too small to be observed using regular optical microscopy. While existing nano-particle imaging systems such as electron microscopy can provide excellent imaging resolution, they are generally limited by high cost, low-throughput and a limited field of view. The research team overcame these limitations by introducing an additional sample preparation step in which liquid nano-lenses were assembled around nano-particles in the sample.
The prepared sample is imaged using digital in-line holography during which the nano-lenses create diffraction patterns caused by their interaction with the holographic light source. These patterns are then detected by a CMOS imaging sensor, reconstructed and analysed for the presence of nano-particles.
While this general approach has been used previously, the presence of the self assembled nano-lenses enabled the researchers to achieve a greater imaging resolution in the sub-micrometer range over the entire CMOS sensor area (~20.5 mm sq.). The researchers believe this will have immediate applications for high throughout point of care detection of viral nano-particles.
To date the team has demonstrated the proof of concept of the technique by imaging sub-100 nanometer adenoviruses and single H1N1 viral particles, and their findings have been published in the journal Nature Photonics.
Study abstract: Wide-field optical detection of nanoparticles using on-chip microscopy and self-assembled nanolenses