Gold Probes Offer Insight into Cancer

Gold nanoprobes paired with FRET microscopy could yield a new generation of biological imaging and sensing techniques capable of studying cancer cells in minute detail, measuring the effectiveness of medicines at subcellular levels and identifying contaminants in food and water supplies.

Gold nanoparticles have a number of advantages over organic dye molecules currently used to study cells with fluorescence microscopy. They are less toxic to cells, more sensitive, probe over a longer distance, and are more photostable — meaning they are unchanged by light exposure.

University of Strathclyde scientists took these advantages into account when developing a multidisciplinary approach using gold nanoprobes paired with FRET microscopy to image message ribonucleic acids (mRNA) — a kind of nucleic acid present in all living cells that carries genetic codes from DNA to make protein. By examining key mRNAs at a cellular level, the scientists could be able to detect diseases — such as cancer — at an early stage, and the effectiveness of treatments.

“The nanoprobes are based on a type of ‘molecular handshake’ called Förster resonance energy transfer — or FRET, in which gold nanoparticles are linked with a fluorescent protein via a hairpin-structured single stranded DNA,” said Dr. Yu Chen of the university’s Department of Physics. “Upon interacting with the target mRNA in the cell, the hairpin structure dissolves and a fluorescent signal occurs — enabling the tracking and quantification of the disease-related mRNA at a cellular level, even down to the level of single molecules.

“The technology could allow the simultaneous detection of multiple types of RNA related to cancer, which would then raise the possibility of scientists eventually being able to screen patients in order to predict their risk of developing disease,” Chen said. “By allowing us to see what is happening inside cells, we also hope this research will also lead to the development of techniques to study the efficacy of drugs.”

The gold probes could be used to deliver other molecules, such as cancer drugs, directly to disease tissues — bypassing normal, healthy cells. They are economical to produce because they only use a tiny trace of the precious metal.

The researchers also believe FRET microscopy with gold nanoparticles could improve food and water safety.

“This new approach to imaging RNA at a single-cell level may also allow scientists to develop new methods to identify various microbes which may have contaminated food and water,” said Dr. Jun Yu of the Strathclyde Institute of Pharmacy and Biomedical Sciences. “Food safety is a global challenge and using novel nanoprobes to detect food contamination by various microbes will open up a new way of addressing this crucial issue.”

“We hope [the approach] will lead to the development of a new generation of biological imaging and sensing techniques that underpin improvements in health care for a range of diseases,” said professor David Birch of the physics department.

The 18-month project was backed with a £119,000 (about $184,000) investment from the Biotechnology and Biological Sciences Research Council.

For more information, visit: www.strath.ac.uk