[Emeriti-faculty] Meeting with Prof. Johnson this Friday

["Staii, Cristian" <Cristian Staii tufts edu>]

Dear colleagues,

Please let me know if you would like to meet with Prof. Johnson, the 
colloquium speaker this Friday and learn more about his adventures in 
nanosience (abstract/title below). Thanks,

Adventures in Nanoscience: Biomimetic Chemical Sensors and DNA 
Translocation through Graphene Nanopores
Prof. A.T. Charlie Johnson
Department of Physics and Astronomy, Univ. of Pennsylvania, Philadelphia, 
PA

Advances in synthesis and understanding of nanomaterials and the potent 
molecular machines of living organisms offer pathways to explore new 
frontiers at the interface of condensed matter physics and biophysics. We 
have recently focused on combinations of carbon nanomaterials, i.e., 
nanotubes (NT) and graphene, with single-stranded DNA or proteins. 
All-electronic vapor sensors can be made, where the biomolecule provides 
chemical recognition, and a nanotube or graphene transistor is used for 
electronic readout. Non-covalent functionalization of NT or graphene 
devices is achieved through self-assembly of single-stranded DNA 
monolayers. The electrical conductance of the device shows a strong and 
reproducible response when exposed to odor-containing vapors, and this 
response is controlled by the base sequence of the DNA. The properties of 
these devices make them intriguing candidates for use in an “electronic 
nose” system whose architecture is inspired by that of the mammalian 
olfactory system. We have studied the structure, dynamics, and 
thermodynamics of this system using all-atom molecular dynamics 
simulations.
In a separate set of experiments we created a nanoelectronic interface to 
olfactory receptor proteins (ORs) that were embedded in synthetic 
nanoscale cell membrane analogues. Olfactory receptor proteins (ORs) are 
the most numerous class of G-protein coupled receptors (GPCRs), a large 
family of membrane proteins whose roles in the detection of molecules 
outside eukaryotic cells and initiation of cascades of intracellular 
responses make them important pharmaceutical targets. The resulting 
devices transduce signals associated with odorant binding to ORs under 
ambient conditions and show responses that are in excellent agreement with 
results from established assays for OR-ligand binding.  The work 
represents significant progress on a path towards an electronic nose that 
can be directly compared to biological olfactory systems as well as a 
general method for the study of GPCR function in multiple domains using 
electronic readout.
Finally, we report on DNA translocations through nanopores created in 
graphene membranes, an approach that may find application in DNA 
sequencing. Due to the thin nature of the graphene membranes, we observe 
larger blocked currents than for traditional solid-state nanopores. Ionic 
current noise levels are several orders of magnitude larger than those for 
silicon nitride nanopores, but can be reduced by application of a thin 
TIO2 layer. In contrast to traditional solid-state nanopore materials that 
are insulating, graphene is an excellent electrical conductor. Use of 
graphene as a membrane material opens the door to a new class of nanopore 
devices in which electronic sensing and control are performed directly at 
the pore.


Cristian Staii
Assistant Professor
Department of Physics and Astronomy
Tufts University,
Science and Technology (STC) Center, Room 209
Medford, MA 02155 USA
Phone: 617-627-5368

email: Cristian Staii tufts edu
https://wikis.uit.tufts.edu/confluence/display/CristianStaiiTuftsUniversity/Home

________________________________________
From: Grant, Gayle [Gayle Grant tufts edu]
Sent: Thursday, April 21, 2011 11:22 AM
To: Department cosmos phy tufts edu
Subject: [Assistant-faculty] Events for Thursday, April 21, 2011 - Journal 
Club and Open House for prospective freshmen and current students

Good morning:

Events for today, Thursday, April 21, 2011 are as follows:

5:00 pm
*Thursday, April 21, 2011
Physics Graduate Students' JOURNAL CLUB
Robinson Hall, Room 250
"A $1,000,000 Problem: Yang-Mills Mass Gap"
Eray Sabancilar
(undergraduate students, faculty and anyone interested are also invited: 
food served at 4:30 pm in Knipp Library)
*Please note change:  Talk is on Thursday this week.


6:30-9:00pm
Thursday April 21, 2011
SPS is hosting an open house event tonight for prospective freshman, as 
well as for any members of the Tufts community Robinson 251 (Physics 
library)
E & M demonstrations by Professor Oliver, pizza, and a presentation by 
Victor Parkinson (a physics graduate student) on the physics behind the 
world of "Avatar", the James Cameron film.
Pizza and soda provided
.

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