APR 29, 2015 12:46 PM PDT

From Smartphone to DNA-Scanning Fluorescent Microscope

WRITTEN BY: Judy O'Rourke
5 49 3935
Scanning one of those strange, square QR codes with your phone looks like a quaint invention compared to a new development from researchers at the University of California, Los Angeles (UCLA).

They have recently developed a device that can turn any smartphone into a DNA-scanning fluorescent microscope.
The imaging device and user interface are shown, with a US quarter for scale.
"A single DNA molecule, once stretched, is about two nanometers in width," says Aydogan Ozcan, HHMI Chancellor Professor, UCLA. "For perspective, that makes DNA about 50,000 times thinner than a human hair. Currently, imaging single DNA molecules requires bulky, expensive optical microscopy tools, which are mostly confined to advanced laboratory settings. In comparison, the components for my device are significantly less expensive."

Enter Ozcan's smartphone attachment - an external lens, thin-film interference filter, miniature dovetail stage mount for making fine alignments, and a laser diode, all enclosed in a small, 3-D-printed case and integrated to act just like a fluorescence microscope.

Although other smart-phone-turned-microscopes can image larger scale objects such as cells, Ozcan's group's latest mobile-phone optical attachment is the first to image and size the slim strand of a single DNA molecule.

The device is intended for use in remote laboratory settings to diagnose various types of cancers and nervous system disorders, such as Alzheimer's, as well as detect drug resistance in infectious diseases.

To use the camera it is necessary to first isolate and label the desired DNA with fluorescent tags. Ozcan says such laboratory procedures are possible even in remote locations and resource-limited settings.

To scan the DNA, the group developed a computational interface and Windows smart application running on the same smart phone. The scanned information is then sent to a remote server in Ozcan's laboratory, which measures the length of the DNA molecules. Assuming you have a reliable data connection, the entire data processing takes less than 10 seconds.

In their lab, Ozcan's group tested the device's accuracy by imaging fluorescently labeled and stretched DNA segments. It reliably sized DNA segments of 10,000 base pairs or longer. (A base pair is the basic structural unit of DNA.) Many important genes fall in this size range, including a bacterial gene notorious for giving Staphylococcus aureus and other bacteria antibiotic resistance that is about 14,000 base pairs long.

The smartphone microscope demonstrated a significant drop in accuracy for 5,000 base-pair or shorter segments, however, due to the reduced detection signal-to-noise ratio and contrast for such short fragments. The problem could easily be remedied by replacing the device's current lens with one of a higher numerical aperture, Ozcan said.

In addition to its use in point-of-care diagnostics, Ozcan proposes that his platform could also be useful for differentiating high molecular weight DNA fragments, which are problematic for conventional gel electrophoresis, a frequently used technique in biochemistry and molecular biology to size DNA and RNA fragments. Ozcan's group next plans to test their device in the field to detect the presence of malaria-related drug resistance.

[Source: The Optical Society]
About the Author
  • Judy O'Rourke worked as a newspaper reporter before becoming chief editor of Clinical Lab Products magazine. As a freelance writer today, she is interested in finding the story behind the latest developments in medicine and science, and in learning what lies ahead.
You May Also Like
APR 21, 2018
Cell & Molecular Biology
APR 21, 2018
An Unhealthy Diet can Permanently Disrupt Fat Cells
The precursors that specialize to become fat cells can be rapidly altered by environmental factors, like fatty food intake.
APR 22, 2018
Genetics & Genomics
APR 22, 2018
Targeting an Invasive Pest with Gene Drive
Scientists have found a way to control the population of an insect invader from Japan that destroys valuable crops.
APR 27, 2018
Health & Medicine
APR 27, 2018
Is Trauma Inherited?
Most people understand what trauma can do to general health. Mental trauma such as experiencing violence or traumatic events, witnessing war or other disas
JUN 15, 2018
Genetics & Genomics
JUN 15, 2018
Why Blood Cells Originate in Bone
Adults typically produce billions of new blood cells every day.
JUN 29, 2018
Microbiology
JUN 29, 2018
Finding a Way to End a Persistent Cholera Epidemic
Tracing back to Indonesia, 1961, the current outbreak has been going on for over fifty years.
JUL 04, 2018
Cell & Molecular Biology
JUL 04, 2018
How Factors Combine to Amplify the Risk of MS
Smoking and exposure to paints had a massive impact when combined with genetic risk factors.
Loading Comments...