Nanoparticles: Targeting via acid/base coiled coils

My project involves conjugating acid/base coiled coils onto nanoparticles for specific targeting. The two nanoparticles that I will be focusing on are Cornell Dots, which will be provided by Professor Uli Wiesner (Department of Material Science and Engineering, Cornell University), and liposomes.

Cornell Dots (C-dots) are fluorescent nanoparticles, which consist of a ‘core’ of dye molecules surrounded by a protective silica shell. Similar to quantum dots, Cornell Dots are 20 to 30 times brighter than single dye molecules in solution and resist photobleaching. However, their advantage over quantum dots is that the Cornell Dots are much more mono-dispersed, inert, and cheaper.

Unlike Cornell Dots, which are relatively new, liposomes have been used frequently as drug delivery vectors because of their biocompatible and biodegradable characteristics. They have an aqueous core entrapped by one or more bilayers composed of lipids, which are effective in protecting encapsulated molecules, such as drugs, from degradation.

The targeting agent will be attached to either of the nanoparticles via E5-K5. E5-K5 is an acid/base coiled coil which have very strong affinity for each other; the association was able to be detected at a range as low as 100pM.

In my effort of protein conjugation via acid/base coiled coils, the following are the immediate goals: (1) conjugation of K5 to nanoparticles, and (2) binding GFP(YFP, or CFP)-E5 to K5-modified fluorescence-encapsulating nanoparticles. Successful binding of GFP-E5 along with YFP-E5 or CFP-E5 will show that multiple targeting is possible, which will in turn Increase targeting specificity and allow for simultaneous targeting and imaging. Eventually, GFP will be replaced with any protein of interest, such as herceptin in targeting Her2-positive breast cancer.

Figure 1: Schematic of protein conjugation via E5-K5