Biomod/2011/MIT/Origami/Process

Idea

We wanted to make a structure that would have precise and compartmentalized drug delivery in reaction to its surroundings.

One edge could react to light via azobenzene conformational changes, the other to pH changes via an I-switch. [IMAGES]

Azobenzene undergoes a conformational change from trans to cis. As it switches, it detaches from the “floor” of the house, causing the floor to “open” and drug particles to be released. The floor can either stay attached by a hinge and swing open, or it can detach around the edges completely but be held by spring-like linkers that attach to the inside of the box and the floor. [IMAGES]

The I-switch is made out of DNA and has a conformational change in response to pH. It also functions as a pH sensor and reporter through a FRET signal. It is functional inside cells. It is composed of three oligonucleotides. The oligonucleotides on the edges have single-stranded cytosine-rich overhangs. At a low pH, these overhangs attract protons and come together, causing the whole structure to fold and thus release the parts of the box that is bound to.