August 14, 2019
by Carol Lynn Alpert
Participating: Jessica (while driving), Peter, Abhijit (delayed by traffic), Abhilasha (by phone from home), Carol Lynn. Faiz was off at TA training.
Optics Team – Georgia
Abhijit produced the team’s first two-color STORM image of the neuromuscular junction (NMJ) in a fruitfly. The myopedia are outlined in green and the filopedia in red, with a resolution of 20 nm.
The target is to see the interactions of these hair-like structures with even higher resolution. Next step: apply a dichroic beam splitter to increase resolution. Ultimately, their collaborator, Daichi Kamiyama, would like superresolution images of the NMJ at three stages: pre, during, and post contact.
Abhijit completed a CAD design for attaching a light sheet generating device to the STORM scope; however, he’s not satisfied with it because he thinks the prism is set too close to the where the slide sits below the objective. He will generate an alternative design.
Peter is reviewing and editing the first draft of the manuscript on imaging 100 nm polystyrene beads with holography.
QDot Team – Ohio
Success! Faiz and Abby tested the new azo double-stranded DNA sequences they ordered and these did hit the desired divergent melting points: 55.2 C for trans-Azo-dsDNA (making it more stable) and less than 15 C for the cis form (destabilizing). Next, they will attach the gold nanoparticles and see if UV light will serve to convert trans to cis, dehybridizing the DNA and unquenching the QD fluorescence. The team is readying a manuscript for the Journal of Chemical Physics.
Jessica is still waiting to hear about funding from NIH for continued work on a diagnostic imaging protocol that uses an ssDNA “erasing” or “strand invasion” technique to remove QD QD micelles caged in DNA tiles from their target antigen. Instead of employing FRET, this technique relies on washing away unbound QDot cages to make it easier to localize remaining fluorophores.
During last month’s phone call, we decided to test this technique for STORM imaging as soon as possible. In the meantime, Carol Lynn asked Jessica, why we couldn’t use the same “strand invasion” technique on our PC3 treated uncaged DNA? That hadn’t been possible previously, when the QDot team yet had good success conjugating QDots to DNA, but now that they have; Jessica thought it was worth a try. So now, we are planning to test the strand invasion STORM imaging technique with both caged and uncaged QDots in Ohio and in Georgia. Suddenly we have two new possibilities for applying QDots to STORM imaging.
Communications Team - Boston
The MOS team is eager to accelerate the performance of these experiments, because if they work, QSTORM will at last be able to demonstrate harnessing of target specific QDots for STORM imaging. We‘d like to include this achievement in the final film about our project, which we are planning to shoot in January. We also hope to include two-color, light sheet-enhanced imaging of Daichi Kamiyama’s investigation into the dynamics of neuromuscular junctions.
Our next meeting is set for Wednesday, Sept 11 at 1 pm.