Shedding new light on tumors

Doctoral candidate Guoqing Zhang with chemistry professor Cassandra Fraser.

The long-lived phosphorescent afterglow is evident only under low- or no-oxygen conditions.

A new oxygen nanosensor that combines a biopolymer with a light-emitting dye could help identify the most aggressive regions of cancerous tumors, according to a press release by researchers at the University of Virginia.

The material uses polylactic acid as its base–good news for the environment and cost because it is both easy and inexpensive to fabricate in many forms.

Guoqing Zhang, a chemistry doctoral candidate, alongside Cassandra Fraser, a chemistry professor, combined a corn-based biopolymer with a dye that is both fluorescent (the immediate illumination of photon re-emission) and phosphorescent (a slower illumination that appears as an afterglow):

Zhang devised a method to adjust the relative intensities of short-lived blue fluorescence and long-lived yellow phosphorescence, ultimately creating a calibrated colorful glow that allows visualization of even minute levels of oxygen. The biomaterial displays its oxygen-sensitive phosphorescence at room or body temperature, making it ideal for use in tissues.

There are several exciting elements to this discovery. First, Zhang managed to combine both times of luminescence into one dye. But also this biomaterial works at room or body temperature, instead of colder temps, which has been a major issue for so long. And also, both the fluorescence and phosphorescence now have similar levels of brightness.

“It is based on a bio-friendly material,” Zhang says. “It is safe for the body and the environment, and so we realized it could have applications not just for medical research and developing improved disease treatments, but also for new sustainable technologies.”

The material is already in preclinical studies to gain insight into cancer biology and treatment, which could influence drug development and testing.

The researchers have consulted with the University of Virginia Cancer Center and Duke University Medical Center to determine additional uses, which could include injectable nanosensors to monitor ongoing oxygen levels and biological processes.

And because oxygen deficiency (hypoxia) is also linked to stroke, diabetes, and cardiovascular disease, the material will likely be useful in multiple areas of medicine, not to mention cellular biology, food and drug packaging, tamper-resistant seals, and the environmental monitoring of such systems as bodies of water, etc.(this news is so big that she says she has been getting calls from high-ups in all sorts of fields, including cardiology, neurology, transplantation surgery, engineering, etc.), and her excitement about this discovery was palpable: “It sounds cheesy, but it’s my dream come true as a scientist for 25 years, a very rare event at least in my life as a scientist that all of that comes together, plus to have the chance to work with such a tremendously talented and creative graduate student as Zhang.”