Micro- and nano-technologies can be used for better molecular diagnostics

Jeff Wang of Johns Hopkins at the annual INBT NanoBio Symposium. Photo by Mary Spiro

Even the smallest mutations in the human genome can be linked to the development of many diseases. Jeff Tza Huei Wang is an associate professor of mechanical engineering at Johns Hopkins University with joint appointments in biomedical engineering and oncology at the Johns Hopkins School of Medicine. He presented a talk at INBT’s annual NanoBio symposium on May 4 that focused on “breaking the barrier from bench to bedside processing” with techniques on the nano and micro scale with high sensitivity and throughput at a low cost.

Quantum dots are an attractive option for ultra sensitive detection of molecules on the nanoscale, Wang said. Wang has developed DNA functionalized quantum dots with the ability of detecting DNA mutations down to levels as low as 10-12 grams.

Methylation of DNA, which is an epigenetic or outside of the genetic code alteration to DNA, can silence genes important in tumor suppression. These quantum dots can also be designed to detect methylation in tumor precursors, which would allow for early detection of cancerous cells in the body.

Polymerase chain reaction (PCR) is a technique used in diagnosis of many diseases and infections like HIV and cancer by creating thousands of copies of DNA from a single DNA sample that can then be screened to find disease-related mutations in cells. This typically must be carried out in a lab and can take weeks to process, but Wang has developed a lab on a chip microfluidic device that can carry out this whole process.

Microdroplets in oil are used as reaction vessels for each stage and super paramagnetitic nanoparticles are able to guide the DNA from droplet to droplet. This device would allow for PCR analysis to happen at a patients’ bedside within a matter of minutes.

Story by Gregg Duncan, a Ph.D. student in the Department of Chemical and Biomolecular Engineering with interests in biomaterials and drug delivery.


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