Viruses as Optical Probes
E-S Kwak, C. Chen, C. Cheng Kao, W.L. Schaich and B. Dragnea
University of Indiana, US
Keywords: virus self-assembly, near-field, optical trap, virus-encapsulation, nanoparticles
Viruses consist of a nucleic acide core, the genome, and a protein shell, the viral capsid. Although made out of only a few types of molecular building blocks, virus capsids exhibit a complex set of functions, which are achieved by large-scale structural transformations. What triggers these transformations, and their sequence is unknown at present. The lack of non-intrusive methods able to follow the transient states in real time and in a physiological environment continues to be the main challenge in studies of the physico-chemical properties of viral self-assembly. Two new experimental approaches are introduced, which have the potential to overcome these problems. The first approach is to partially replace the RNA core inside the capsid by nanoparticles having the role of spectroscopic enhancers. This allows us to optically detect and measure a single virus at a time. The second approach is to use light to trap single viruses inside nanochannels lithographically patterned on a surface. The virus is thus kept from drifting away from the analytical volume by Brownian motion. These two approaches, combined, will give the possibility of doing time-resolved spectroscopy on individual viruses and therefore follow the transient states without averaging over a large population of asynchronous viruses. Another opportunity opened by our methodology is intracellular imaging using viruses as optical probes.
Nanotech 2004 Conference Technical Program Abstract