Better bioimaging for cancer research
Image: Rapid spectroscopic imaging of polymers could lead to better bioimaging [Wrobel/Beckman Institute]
US-based researchers have shown that Quantum Cascade Laser-based (QCL) infrared spectroscopic imaging can examine spherulites, large semicrystalline polymer samples, more rapidly than conventional Fourier transform infrared imaging (FTIR).
The method can be used to swiftly image molecular orientation in large sample areas, which could prove critical to cancer diagnosis in clinical settings.
As Tomasz Wrobel from the Beckman Institute for Advanced Science and Technology highlights: “We call it smart microscopy because we only spend time measuring frequencies which are important for our given problem."
"Instead of shining a light from all frequencies, we choose those two to three crucial discrete frequencies," he says.
IR spectroscopic imaging has been used to measure the composition and orientation of polymeric systems for decades.
But while IR microscopy provides detailed views of microscopic regions, a trade-off exists between the size of area to be imaged and detail of molecular properties.
Given this, Wrobel and colleagues wanted to test how far they could push discrete frequency infrared spectroscopic imaging, based on a QCL, in terms of speed and signal-to-noise ratio (SNR).
According to the researcher, FTIR also uses a large number of frequencies, compromising imaging speed across a small area.
But their method uses the individual narrowband emission lines of a QCL source to spectrally image large areas rapidly.
What's more, the inherent polarisation of the laser beam meant the method is suited to providing structural information on systems with an orientation dependency, such as spherulites.
“We came up with approximately 180 factor of speed improvement over the technology that does not use the QCL," says Wrobel. "We achieve this through the new laser source, which is emitting just one frequency of light at a time."
FTIR allowed the researchers to acquire all of the frequencies that correspond to chemical properties in order to choose the correct light frequency to quickly glean the sample information they need.
This approach was used in a prototype instrument developed with Agilent Technologies in collaboration with Rohit Bhargava’s group at the Beckman Institute.
“We can have a beautiful visualization of the structure in a very rapid fashion, comparable or even faster than in the visible range, which is the state of the art,” adds Wrobel. “Given that also we achieve chemical composition, not only structure, this is a very nice method of doing that in a fast way on a large scale, both chemically and structurally.”
Wrobel focuses on developing imaging techniques to improve how prostate cancer is diagnosed.
Working with Bhargava, a professor of bioengineering and a member of Beckman’s Bioimaging Science and Technology Group, Wrobel hopes to broaden the technique for biological samples in a clinical setting.
“I am working on speeding up cancer diagnoses, because diagnosis of cancer has been done with FTIR,” says Wrobel. “A clinical setting requires speed, which we didn’t have previously, so now I’m pushing QCL to diagnose cancer on a clinically relevant scale.”
Research is published in Analyst.