PHOTOCLEAVABLE QUANTUM DOT-GOLD NANOPARTICLE SYSTEMS FOR SUPER-RESOLUTION IMAGING

Abstract

The ability to directly see structures and observe biological processes below the 200 nm resolution limit of traditional optical imaging methods would enable substantial advances in biology. Super-resolution imaging techniques use the bright/dark states of fluorescent probes and computer algorithms to image beyond that barrier by imaging probes in small groups rather than all at once. Quantum dots (QDs) have advantages over the florescent dyes and proteins currently used because of their increased brightness, stability, and resistance to photobleaching. However, they cannot be turned on and off stochastically. Here, we describe a QD-gold nanoparticle (AuNP) system that uses Förster (fluorescence) nonradiative energy transfer (FRET) for potential application in super-resolution imaging. When the composite is formed using a linker, it is dark, but when the linker is cleaved by light energy, QD fluorescence is restored. The initial conjugation was not successful because of instability of the AuNP. The AuNP was stabilized by using triethylene glycol mono-11-mercaptoundecyl ether, but no FRET was detected. Analysis with a transmission electron microscope demonstrated very few conjugated samples. FRET was tested using high concentrations of AuNPs and QDs, but without clear quenching. Future work would include using a shorter, reversible linker, such as molecules that change conformation upon UV light or shrinkable/stretchable polymers.