"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."
This proposal requests the purchase of a Quanta 250 FEG environmental scanning electron microscope (ESEM) from FEI for nanometer-scale imaging and analysis of biological samples under near-biological environmental conditions. The proposed instrument is to be housed within the Center for Nano- and Molecular Science and Technology (CNM) at the University of Texas at Austin (UT Austin), and used for original research by student and faculty users representing 10 academic departments. The instrument will allow researchers to examine the structure and composition of hydrated materials under precisely controlled environmental conditions, which will provide a heretofore-unattainable degree of detail (down to 1.4 nm resolution) in the many areas of cutting-edge research using hydrated materials in areas such as drug delivery, tissue engineering, drug-resistant bacterial strains, and development of nanosensors to name just a few. The ESEM can be configured to operate as a scanning transmission electron microscope (STEM) for even more in-depth analysis of hydrated samples, and will allow elemental data analysis via energy-depletion x-ray analysis (EDS).
The University of Texas at Austin has a number of state-of-the-art conventional SEM imaging systems, but is critically lacking a contemporary ESEM. Currently, there is only one ESEM user-facility on campus (in Geosciences), but this is an older system that lacks the resolution (tungsten filament system versus Schottky field emission for the proposed system) and capabilities required for imaging biological samples and micro/nano-materials in their more natural, hydrated state. Due to the ability of the proposed ESEM to image hydrated samples, researchers who were previously unable to use electron microscopy will now have a powerful tool that will open new avenues of research. Additionally, researchers working with biological and other hydrated samples that previously used electron microscopy will have better and complementary imaging data. The ESEM will be maintained by the Texas Materials Institute (TMI) in conjunction with the CNM and it will be centrally located in the CNM's Nano Science and Technology (NST) building. The instrument will be managed by the current facility manager, Dr. Hugo Celio, who has extensive experience in using electron microscopes, in training others in their use, and in performing instrument maintenance. An extended maintenance contract with the manufacturer will also be purchased. This instrument will be available at all times for all eligible users, via a system of controlled access already successfully implemented by the CNM, which balances access with security.
State-of-the-art research in the areas of material science, biopolymers, virology, plant biology, cell and tissue physiology, as well as nano- and micro-devices require high resolution imaging to better understand sample organization, morphology, and levels of interactions between components of the system. High resolution imaging typically consists of scanning electron microscopy (SEM) and transmission electron microscopy (TEM), both of which have significant limitations, especially with biological samples and soft materials. In particular, conventional high vacuum SEM requires hydrated and non-conductive samples to be dried and sputter coated with carbon or gold, which unfortunately, introduces artifacts and severely compromises the morphological integrity of the sample. In contrast, an environmental SEM allows samples to be imaged under low vacuum and in high humidity environments; thus, hydrated and non-conductive samples do not need to be dried or coated in order to be imaged, allowing these samples to be imaged in a more native environment and eliminating the introduction of artifacts. Thus, ESEM is absolutely critical for any sort of imaging in the "wet" state (e.g., hydrogels, nanoparticles, colloidal suspensions, drug delivery microparticles, cells, tissue and biological specimens like viruses and pathogens), and is also useful for imaging non-conductive specimens in a more natural state without modification (e.g., polymers, ceramics, papers, fabrics). An ESEM is also highly useful for observing phase transition processes such as crystallization, freezing, and outgassing of materials, which cannot be imaged using conventional high vacuum SEM. The objective of this proposal was to acquire a cutting edge field emission environmental scanning electron microscope (FE ESEM) for the University of Texas at Austin and the central Texas academic science and engineering community. The instrument chosen for purchase was a Quanta 650 FE ESEM. This instrument was installed in November 2010 and managed as a user facility under the supervision Dr. Hugo Celio, facility manager and Texas Materials Institute (TMI). Except for routine, scheduled maintenance the FE-ESEM has been in continuous operation and available for student users; and since that time an average of 75 hours/month have been billed to users at rates approved by UT. The instrument is 95% self-supporting, with the balance of funding coming from the TMI. So far a total of 47 users have been trained including: 2 visiting scholars, 11 postdoctoral fellows, 33 graduate students. This instrument has already provided significant impact several areas of research and fills a crucial gap in characterizing materials in the hydrated state and with nanoscopic dimensions. Two manuscripts are in preparation that contain data acquired on the new instrument.
