IDBR: Type A, An Ultraprecise and Ultrastable Atomic Force Microscope for Multimodal Characterization of Biological Molecules and Materials

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

This award to the University of Colorado at Boulder, by the Instrument Development for Biological Research program, in the Division of Biological Infrastructure (Biological Sciences Directorate),is jointly funded by the Biomaterials Program in the Division of Materials Science (Math and Physical Sciences Directorate). Atomic force microscopy (AFM) is a tool used for imaging, measuring, and manipulating matter at the nanoscale, and gathers surface information by using a mechanical probe called a cantilever. Applications of AFM in biology include understanding the folding and unfolding of individual proteins. Protein function requires proper folding, and misfolding can lead to diseases such as Alzheimer's. In folding studies, force stability is critical since the folding and unfolding rates are sensitive to sub-piconewton (pN) changes in force. This project merges cost-effective micromachining of cantilevers with a novel optical detection to achieve a 1,600-fold increase in temporal resolution at 1 pN. The proposed developments will benefit the fields of biology, as well as materials science. Project activities will provide excellent interdisciplinary training for undergraduates as well as graduate students. The twin goals of this project are to develop a next generation AFM for biological measurements that achieves (i) world-leading short-term force precision coupled with state-of-the-art force stability and (ii) extend its imaging capability beyond topography to map chemical composition with enhanced resolution. The first goal will be demonstrated in the context of protein folding assays. To provide a 10-100-fold improvement in force stability, a novel differential detection system of cantilever motion will be developed. This system will use a tiny spot size (~2 ìm) to enable detection of ultra-small (L = 10 ìm) cantilevers, which have been modified by a focused ion beam for improved performance. These cantilevers enable world-leading force precision coupled with sub-pN stability over long periods (100 s). The second project goal focuses on chemical characterization of materials using a new Raman imaging modality that offers 3.5-nm resolution. By scattering multiple laser beams off the AFM tip, the proposed AFM will synergistically merge this exciting imaging modality with the world-leading tip-sample stability and builds upon a strength of the PI?s lab: integrating multiple lasers into an AFM. Initial studies will focus on DNA wrapped carbon nanotubes. Results will be disseminated via papers, presentations, and patents. Biological research communities that will benefit from this project include single-molecule biophysics, membrane protein biology, cellular structure, protein folding, as well as other disciplines (e.g., physics, material science, & nanotechnology). Collaborations with AFM manufacturers (including Asylum Research and Molecular Vista) will facilitate adoption by a wider user base.