Media Releases

U of T researchers build an antenna for light

July 11, 2011

TORONTO, ON – Uni­ver­si­ty of Toron­to researchers have derived inspi­ra­tion from the pho­to­syn­thet­ic appa­ra­tus in plants to engi­neer a new gen­er­a­tion of nano­ma­te­ri­als that con­trol and direct the ener­gy absorbed from light.

Their find­ings are report­ed in a forth­com­ing issue of Nature Nan­otech­nol­o­gy, which will be released on July 10, 2011.

The U of T researchers, led by Pro­fes­sors Shana Kel­ley and Ted Sar­gent, report the con­struc­tion of what they term “arti­fi­cial mol­e­cules.”

“Nan­otech­nol­o­gists have for many years been cap­ti­vat­ed by quan­tum dots – par­ti­cles of semi­con­duc­tor that can absorb and emit light effi­cient­ly, and at cus­tom-cho­sen wave­lengths,” explained co-author Kel­ley, a Pro­fes­sor at the Leslie Dan Fac­ul­ty of Phar­ma­cy, the Depart­ment of Bio­chem­istry in the Temer­ty Temer­ty Fac­ul­ty of Med­i­cine, and the Depart­ment of Chem­istry in the Fac­ul­ty of Arts & Sci­ence. “What the com­mu­ni­ty has lacked – until now – is a strat­e­gy to build high­er-order struc­tures, or com­plex­es, out of mul­ti­ple dif­fer­ent types of quan­tum dots. This dis­cov­ery fills that gap.”

The team com­bined its exper­tise in DNA and in semi­con­duc­tors to invent a gen­er­al­ized strat­e­gy to bind cer­tain class­es of nanopar­ti­cles to one anoth­er.

“The cred­it for this remark­able result actu­al­ly goes to DNA: its high degree of speci­fici­ty – its will­ing­ness to bind only to a com­ple­men­tary sequence – enabled us to build ratio­nal­ly-engi­neered, design­er struc­tures out of nano­ma­te­ri­als,” said Sar­gent, a Pro­fes­sor in The Edward S. Rogers Sr. Depart­ment of Elec­tri­cal & Com­put­er Engi­neer­ing at the Uni­ver­si­ty of Toron­to, who is also the Cana­da Research Chair in Nan­otech­nol­o­gy. “The amaz­ing thing is that our anten­nas built them­selves – we coat­ed dif­fer­ent class­es of nanopar­ti­cles with select­ed sequences of DNA, com­bined the dif­fer­ent fam­i­lies in one beaker, and nature took its course. The result is a beau­ti­ful new set of self-assem­bled mate­ri­als with excit­ing prop­er­ties.”

Tra­di­tion­al anten­nas increase the amount of an elec­tro­mag­net­ic wave – such as a radio fre­quen­cy – that is absorbed, and then fun­nel that ener­gy to a cir­cuit. The U of T nanoan­ten­nas instead increased the amount of light that is absorbed and fun­neled it to a sin­gle site with­in their mol­e­cule-like com­plex­es. This con­cept is already used in nature in light har­vest­ing anten­nas, con­stituents of leaves that make pho­to­syn­the­sis effi­cient. “Like the anten­nas in radios and mobile phones, our com­plex­es cap­tured dis­persed ener­gy and con­cen­trat­ed it to a desired loca­tion. Like the light har­vest­ing anten­nas in the leaves of a tree, our com­plex­es do so using wave­lengths found in sun­light,” explained Sar­gent.

“Pro­fes­sors Kel­ley and Sar­gent have invent­ed a nov­el class of mate­ri­als with entire­ly new prop­er­ties. Their insight and inno­v­a­tive research demon­strates why the Uni­ver­si­ty of Toron­to leads in the field of nan­otech­nol­o­gy,” said Pro­fes­sor Hen­ry Mann, Dean of the Leslie Dan Fac­ul­ty of Phar­ma­cy.

“This is a ter­rif­ic piece of work that demon­strates our grow­ing abil­i­ty to assem­ble pre­cise struc­tures, to tai­lor their prop­er­ties, and to build in the capa­bil­i­ty to con­trol these prop­er­ties using exter­nal stim­uli,” not­ed Paul S. Weiss, Fred Kavli Chair in NanoSys­tems Sci­ences at UCLA and Direc­tor of the Cal­i­for­nia NanoSys­tems Insti­tute.

Kel­ley explained that the con­cept pub­lished in today’s Nature Nan­otech­nol­o­gy paper is a broad one that goes beyond light anten­nas alone.

“What this work shows is that our capac­i­ty to manip­u­late mate­ri­als at the nanoscale is lim­it­ed only by human imag­i­na­tion. If semi­con­duc­tor quan­tum dots are arti­fi­cial atoms, then we have ratio­nal­ly syn­the­sized arti­fi­cial mol­e­cules from these ver­sa­tile build­ing blocks.”

Also con­tribut­ing to the paper were researchers Sjo­erd Hoog­land and Armin Fis­ch­er of The Edward S. Rogers Sr. Depart­ment of Elec­tri­cal & Com­put­er Engi­neer­ing, and Grig­o­ry Tikhomirov and P. E. Lee of the Leslie Dan Fac­ul­ty of Phar­ma­cy.

The pub­li­ca­tion was based in part on work sup­port­ed by the Ontario Research Fund Research Excel­lence Pro­gram, the Nat­ur­al Sci­ences and Engi­neer­ing Research Coun­cil of Cana­da (NSERC), Cana­da Research Chairs pro­gram and the Nation­al Insti­tutes of Health (NIH).

To read the pub­lished paper in its entire­ty, please con­tact Jef Ekins, Man­ag­er, Mar­ket­ing & Com­mu­ni­ca­tions, Leslie Dan Fac­ul­ty of Phar­ma­cy, Uni­ver­si­ty of Toron­to.


About Phar­ma­cy at the Uni­ver­si­ty of Toron­to
The Leslie Dan Fac­ul­ty of Phar­ma­cy at the Uni­ver­si­ty of Toron­to is Canada’s largest fac­ul­ty of phar­ma­cy, an inter­na­tion­al­ly rec­og­nized leader in phar­ma­cy edu­ca­tion and pre-emi­nent cen­tre for inno­va­tion and dis­cov­ery in phar­ma­ceu­ti­cal sci­ences.

For more infor­ma­tion, please con­tact:

Jef Ekins
Man­ag­er, Mar­ket­ing & Com­mu­ni­ca­tions
Leslie Dan Fac­ul­ty of Phar­ma­cy,
Uni­ver­si­ty of Toron­to