To speed up biotechnology innovations, corresponding to the event of lifesaving drug therapies, scientists strive to develop faster, more quantitative and more widely available ways to watch biomolecules in living cells.
Researchers on the National Institute of Standards and Technology (NIST) have developed a brand new method that enables using infrared (IR) light to capture clear images of biomolecules inside cells, something that was previously impossible attributable to the tendency of the water in cells to soak up infrared radiation. The brand new method removes the obscuring effects of water in IR-based measurements and allows researchers to find out the amounts of key biomolecules in cells, corresponding to the proteins that direct cell function. The power to measure changes in living cells could speed up advances in biomanufacturing, cell therapy development, drug development and more.
Their findings have been published in Analytical Chemistry.
Infrared radiation is light that’s just beyond what’s visible to the human eye. Although we cannot see IR light, we will feel it as heat. In IR microscopy, a cloth of interest absorbs radiation from a variety of wavelengths within the IR spectrum. Scientists measure and analyze the IR absorption spectrum of a sample, producing a set of “fingerprints” to discover molecules and other chemical structures. Nevertheless, water, essentially the most abundant molecule each inside and outdoors cells, absorbs infrared strongly and masks the infrared absorption from other biomolecules in cells.
One solution to understand this optical masking effect is to match it to when an airplane passes overhead next to the Sun. With the naked eye, it’s hard to see the airplane due to the Sun, but in the event you use a special Sun-blocking filter, then you definately can easily see the airplane within the sky.
“Within the spectrum, water absorbs infrared so strongly, and we wish to see the absorption spectrum of proteins through the thick water background, so we designed the optical system to uncloak the water contribution and reveal the protein signals,” said NIST chemist Young Jong Lee.
Lee developed a patented technique that uses an optical element to compensate for water absorption from IR. Called solvent absorption compensation (SAC), the technique was used with a hand-built IR laser microscope to image cells that support the formation of connective tissue, called fibroblast cells. Over a 12-hour statement period, researchers were in a position to discover groups of biomolecules (proteins, lipids and nucleic acids) during stages of the cell cycle, corresponding to cell division. While this may increasingly seem to be an extended time, the tactic is ultimately faster than current alternatives, which require beam time at a big synchrotron facility.
This recent method, called SAC-IR, is label-free, meaning it doesn’t require any dyes or fluorescent markers, which may harm cells and in addition produce less consistent results across labs.
The SAC-IR method enabled NIST researchers to measure absolutely the mass of proteins in a cell, along with nucleic acids, lipids and carbohydrates. The technique could help establish a foundation for standardizing methods for measuring biomolecules in cells, which could prove useful in biology, medicine and biotechnology.
“In cancer cell therapy, for instance, when cells from a patient’s immune system are modified to higher recognize and kill cancer cells before being reintroduced back to the patient, one must ask, ‘Are these cells secure and effective?’ Our method might be helpful by providing additional insight with respect to biomolecular changes within the cells to evaluate cell health,” said Lee.
Other potential applications include using cells for drug screening, either in discovery of recent drugs or in understanding the protection and efficacy of a drug candidate. For instance, this method could help to evaluate the potency of recent drugs by measuring absolute concentrations of varied biomolecules in numerous individual cells, or to investigate how various kinds of cells react to the drugs.
The researchers hope to develop the technique further so it could measure other key biomolecules, corresponding to DNA and RNA, with greater accuracy. The technique could also help provide detailed answers to fundamental questions in cell biology, corresponding to what biomolecule signatures correspond with cell viability — in other words, if the cell is alive, dying or dead.
“Some cells are preserved in a frozen state for months or years, then thawed for later use. We do not yet fully understand how best to thaw the cells while maintaining maximum viability. With our recent measurement capabilities, we may give you the chance to develop higher processes for cell freezing and thawing by taking a look at their infrared spectra,” said Lee.
