The development of clustered regularly interspaced short-palindromic repeat (CRISPR)-Cas systems for genome editing has transformed the way life science research is conducted and holds enormous potential for the treatment of disease as well as for many aspects of biotechnology. Here, I provide a personal perspective on the development of CRISPR-Cas9 for genome editing within the broader context of the field and discuss our work to discover novel Cas effectors and develop them into additional molecular tools. The initial demonstration of Cas9-mediated genome editing launched the development of many other technologies, enabled new lines of biological inquiry, and motivated a deeper examination of natural CRISPR-Cas systems, including the discovery of new types of CRISPR-Cas systems. These new discoveries in turn spurred further technological developments. I review these exciting discoveries and technologies as well as provide an overview of the broad array of applications of these technologies in basic research and in the improvement of human health. It is clear that we are only just beginning to unravel the potential within microbial diversity, and it is quite likely that we will continue to discover other exciting phenomena, some of which it may be possible to repurpose as molecular technologies. The transformation of mysterious natural phenomena to powerful tools, however, takes a collective effort to discover, characterize, and engineer them, and it has been a privilege to join the numerous researchers who have contributed to this transformation of CRISPR-Cas systems.

Self-assembly is a powerful method for fabricating structures and devices with nanoscale dimensions. Many proposed applications, such as patterned magnetic media [1][2][3] and nanowire transistors, [4] require placement of nanoscale features into ordered arrays with high placement precision and accuracy. Positional disorder degrades the performance of such devices. For instance, in a patterned magnetic medium, disorder in the magnetic array would lead to noise in the read-back signal. To achieve long-range spatial-phase coherence, and hence pattern registration in self-assembling systems for applications requiring high placement accuracy, a lithographically defined template can be used to direct the positions of the self-assembled features. This process, in which patterned templates guide the arrangement of self-organizing materials, is called templated self-assembly (TSA). TSA has been applied to a wide range of systems, including quantum-dot formation, [5] assembly of colloidal spheres, [6] and microphase separation in block copolymers. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] With proper template design, TSA enables the formation of well-ordered, high-density arrays. However, there has been little quantitative study of the positional accuracy of templating, even though this is a key issue in integrating self-assembled processing steps into practical device fabrication. In this paper, we characterize the placement accuracy of arrays of block-copolymer domains in topographical templates, and assess the limiting factors for the pattern registration of templated block copolymers. Block copolymers are composed of covalently linked blocks of monomer units. They can microphase separate into nanoscale periodic structures that may be ideal for many applications. [20][21][22][23][24][25][26] However, thin films of microphase-separated block copolymers typically do not have long-range translational order, which limits their usefulness. Templating can be achieved by using a lithographically defined patterned substrate and has successfully generated arrays of spherical, cylindrical, or lamellar block-copolymer nanostructures with long-range order. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] Although these templated polymer arrays qualitatively appear to be uniform and well ordered, there has been no quantitative analysis of the influence of template irregularities on the perfection of the array. To explore this issue, we have analyzed the effect of line-edge roughness of the template on the self-assembly of a spherical-morphology block copolymer and demonstrated precise polymer domain registration by employing two-dimensional (2D) templates. Scanning electron-beam lithography was used to expose a 100 nm thick film of hydrogen silsesquioxane (HSQ), a negative resist, on oxidized silicon wafers. Development of the HSQ creates grooves with vertical sidewalls and the surface of the developed HSQ resembles oxidized silicon. Solutions of 1.5 % polystyrene (PS)-block-polyferrocenyldimethylsilane (PFS) [27] ...