Using the Molecular Foundry's imaging capabilities, scientists developed a technique, called "CLAIRE," that allows the incredible resolution of electron microscopy to be used for non-invasive imaging of biomolecules and other soft matter. The new technique offers both clarity and speed.
CLAIRE could lead to the understanding of key biological processes and help accelerate the development of new technologies such as high-efficiency photovoltaic cells.
Soft matter encompasses a broad swath of materials, including liquids, polymers, gels, foam and—most importantly—biomolecules. At the heart of soft materials, governing their overall properties and abilities, are the interactions of nano-sized components. Observing the dynamics behind these interactions is critical to understanding key biological processes, such as protein crystallization and metabolism, and could help accelerate the development of important new technologies, such as artificial photosynthesis or high-efficiency photovoltaic cells. Observing these dynamics at sufficient resolution has been a major challenge, but scientists are now meeting this challenge with a new non-invasive nanoscale imaging technique that goes by the acronym of CLAIRE.
CLAIRE stands for "cathodoluminescence activated imaging by resonant energy transfer" and combines elements of optical and scanning microscopy into a single imaging platform. The system utilizes an ultrathin scintillating film that is placed between the electron beam and sample. When the film is excited by the electron beam, it transfers energy and causes the sample to radiate. In this way, an image can be formed that is not restricted by the optical diffraction limit.
Invented by users of the Molecular Foundry, CLAIRE extends the incredible resolution of electron microscopy to the dynamic imaging of soft matter. The research team demonstrated CLAIRE's imaging capabilities by applying the technique to aluminum nanostructures and polymer films that could not have been directly imaged with electron microscopy. They obtained optical images of aluminum nanostructures with 46-nanometer resolution and then validated the non-invasiveness of CLAIRE by imaging a conjugated polymer film. The high resolution, speed, and non-invasiveness could transform the way key biomolecular interactions are studied.
Lawrence Berkeley National Laboratory
YAP:Ce film deposition and CL characterization were supported by the National Science Foundation (NSF) under Grant Number 1152656. Nanofabrication was supported by the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy, FWP number SISGRN. Devices were fabricated both at the Marvell Nanofabrication Laboratory and Biomolecular Nanotechnology Center at University of California, Berkeley. CL and time-resolved fluorescence at the Berkeley Lab Molecular Foundry were performed as part of the Molecular Foundry user program, supported by the Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Z.W. and D.G.S. acknowledge support under the Air Force Office of Scientific Research Grant No. FA9550-10-1-0123, C.G.B. acknowledges an NSF Graduate Research Fellowship (DGE 1106400) and N.S.G. acknowledges a David and Lucile Packard Fellowship for Science and Engineering. We thank S. Aloni and D. F. Ogletree for providing technical and theoretical advice, and we thank R. Ramesh for access to thin film deposition PLD facilities.
C. G. Bischak, C. L. Hetherington, Z. Wang, J. T. Precht, D. M. Kaz, D. G. Schlom, and N. S. Ginsberg, "Cathodoluminescence-activated nanoimaging: Noninvasive near-field optical microscopy in an electron microscope." Nano Letters 15, 3383 (2015). [DOI: 10.1021/acs.nanolett.5b00716].