Seeing the first images of Earth, a shiny blue and white ball suspended against inky blackness, changed the way we think about the world. Slowing down droplets as they hit a liquid surface, sending out ripples and kicking up globules, or seeing bullets shooting towards us in slow-motion from a movie screen, belong to our vocabulary of visual experiences.
A new tool developed by Berkeley Labs now helps scientists glimpse images that seem equally amazing: watching individual proteins, and other biomolecules, at work inside cells. Because our bodies rely on chemicals for communication between cells, the new technique opens windows that will help lead to cures for immune system conditions, cancer, and other diseases.
Seeing how biomolecules function in normal systems and comparing the functionality in cells contaminated with suspected disruptive pollutants, like Bisphenol-A or phthalates, could lead to insights, perhaps even screening tests, on which industrial chemicals are sufficiently low risk to be useful and which need to be avoided in the interest of health. Scientists could answer questions like: can chemicals make us fat?
How does it work?Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley, led by chemist Jay Groves, have developed a lipid membrane studded with gold nano-antennas. A lipid membrane is just a wall of fatty molecules that like to hang out together, like soap films surrounding a soap bubble. Lipid membranes form cell walls in our bodies.
The gold nano-antennas magnify signals from molecules that move freely through the nano-antenna field. They are also being called "bow-tie" nano-antennas because each consists of two triangular nanoparticles of gold pointing towards each other like a bow-tie. Scientists attach an SOS-catalyst (solid oxide solution catalyst) to the protein; it's fluorescence is magnified as it passes through the gateway between antennas in the array.
Most of the imaging techniques used, such as fluorescent emissions and Raman spectroscopy, are well-established methods. The breakthrough achieved by the Berkeley team consists of arranging a regular array of nano-particle bow-tie antennas, necessary to reinforce "plasmonic hot spots" that boost the intensity of signals, and setting up an observation chamber where biomolecules can go about their business uninterrupted. The ability to observe molecules without interfering with their motions can be critical to understanding complex biomechanical systems.