December 13, 2018
by Carol Lynn Alpert
All present for our final meeting of 2018.
Optics Team (Georgia)
The Optics team took advantage of their move to a new lab space to make some user-friendly changes to the holographic microscope setup. Most importantly, they replaced their Spatial Light Modulator with a Michelson interferometer. While the interferometer (on the black plate in the center of the table) is less flexible than the SLM, it will more than double light collection efficiency. This improvement addresses the “read noise” problem the team has been contending with for the past several months. See Abhijit’s new blog post for more details and the very first test images of 200 nm fluorescent microspheres using the new interferomete
Meanwhile, in Ohio, Kil Ho has prepared new micelle-coated QDs at the desired 680 nm fluorescence to ship to Georgia so Abhijit can test imaging them with the holographic scope. They’re packaged up and ready to ship.
QDot Team (Ohio)
Speaking of Kil Ho, he and Faiz, the lab’s new graduate student, have been exploring a number of variables that may allow them to optimize the yield from their DNA embedding procedure on quantum dots by getting more strands of DNA embedded per QD. They detailed two such test variables in the new blog post and during the call: heat and 3-MPA concentration. They determined that both heating and the addition of excess 3-MPA do facilitate embedding of DNA in the QD ZnS shells and increase fluorescence yield. Kil Ho and Faiz also made their first attempt to hybridize QD conjugated with poly T ssDNA and gold nanoparticles (AuNPs) conjugated with complementary poly A ssDNA. If the hybridization had been successful, the gold nanoparticles should have quenched or at least diminished the QD fluorescence through the FRET (Forster Resonance Energy Transfer) mechanism. Quenching was not observed, and because QD quenching is critical for the on-off switching required for STORM microscopy, this failure must be investigated. Abby experienced a similar problem in her efforts this month to hybridize composites of her QD-DNA conjugates with AuNP-DNA conjugates, also through complementary A-T base pair bonding. The QDot team suspects that the gold nanoparticles are not being properly passivated and don’t have enough ssDNA attached to their surfaces. They will address this challenge over the next several weeks.
This month Abby also endeavored to increase the purification efficiency necessary for isolating ssDNA-QD conjugates from unconjugated elements, producing a higher yield. She determined that centrifugal filtration works best to remove excess and unconjugated DNA from solution, but that there must also be an additional filtering step to separate excess and unconjugated QDs.
Communications Team (Boston)
Karine and Carol Lynn both delivered talks at the 2018 NSF Nanoscale Science and Engineering Grantees Conference in Alexandria. They also screened the 2018 Quantum Matters™ Science Communication Competition Finals film and presented a poster on the effort to build a quantum education community. Comments were very positive. The Museum's Current Science & Technology educators are all delivering a segment of the 2018 Top Ten science stories report that our team developed on new super-resolution imaging videos coming out of Nobel Laureate Eric Betzig’s lab. We also produced a new 100-second promo for the Quantum Matters™ film, at www.mos.org/qmc2018promo.
Our next QSTORM-AO meeting is scheduled for 3 pm on January 17th. See you next year.