Media Releases

Pour, shake and stir

March 1, 2013

How gold particles, DNA and water have the potential to shape the future of medicine

TORONTO, ON — A diag­nos­tic “cock­tail” con­tain­ing a sin­gle drop of blood, a drib­ble of water, and a dose of DNA pow­der with gold par­ti­cles could mean rapid diag­no­sis and treat­ment of the world’s lead­ing dis­eases in the near future. The cock­tail diag­nos­tic is a home­grown brew being devel­oped by Uni­ver­si­ty of Toron­to’s Insti­tute of Bio­ma­te­ri­als and Bio­med­ical Engi­neer­ing (IBBME) PhD stu­dent Kyryl Zagorovsky and Pro­fes­sor War­ren Chan that could change the way infec­tious dis­eases, from HPV and HIV to malar­ia, are diag­nosed.

And it involves the same tech­nol­o­gy used in over-the-counter preg­nan­cy tests.

“There’s been a lot of empha­sis in devel­op­ing sim­ple diag­nos­tics,” says IBBME Pro­fes­sor and Cana­da Research Chair in Nanobiotech­nol­o­gy, War­ren Chan. “The ques­tion is, how do you make it sim­ple enough, portable enough?”

The recent win­ner of the NSERC E.W.R. Stea­cie Memo­r­i­al Fel­low­ship, Pro­fes­sor Chan and his lab study nanopar­ti­cles: in par­tic­u­lar, the use of gold par­ti­cles in sizes so small that they are mea­sured in the nanoscale. Chan and his group are work­ing on cus­tom-design­ing nanopar­ti­cles to tar­get and illu­mi­nate can­cer cells and tumours, with the poten­tial of one day being able to deliv­er drugs to can­cer cells.

But it’s a study recent­ly pub­lished in Ange­wandte Chemie, a top chem­istry jour­nal pub­lished out of Ger­many, that’s rais­ing some inter­est­ing ques­tions about the future of this rel­a­tive­ly new fron­tier of sci­ence.

Zagorovsky’s rapid diag­nos­tic biosen­sor will allow tech­ni­cians to test for mul­ti­ple dis­eases at one time with one small sam­ple, and with high accu­ra­cy and sen­si­tiv­i­ty. The biosen­sor relies upon gold par­ti­cles in much the same vein as your aver­age preg­nan­cy test. With a preg­nan­cy test, gold par­ti­cles turn the test win­dow red because the par­ti­cles are linked with an anti­gen that detects a cer­tain hor­mone in the urine of a preg­nant woman.

“Gold is the best medi­um,” explains Chan, “because it’s easy to see. It emits a very intense colour.”

Cur­rent­ly sci­en­tists can tar­get the par­tic­u­lar dis­ease they are search­ing for by link­ing gold par­ti­cles with DNA strands: when a sam­ple con­tain­ing the dis­ease gene (i.e. Malar­ia) is present, it clumps the gold par­ti­cles, turn­ing the sam­ple blue. Rather than clump­ing the par­ti­cles togeth­er, Zagorovsky immers­es the gold par­ti­cles in a DNA-based enzyme solu­tion (DNA-zyme) that, when the dis­ease gene is intro­duced, ‘snip’ the DNA from the gold par­ti­cles, turn­ing the sam­ple red.

“It’s like a pair of scis­sors,” Zagorovsky explains, “and the tar­get gene acti­vates the scis­sors that cut the DNA links hold­ing gold par­ti­cles togeth­er.”

The advan­tage is that far less of the gene needs to be present for the solu­tion to show notice­able colour changes, ampli­fy­ing detec­tion. A sin­gle DNA-zyme can clip up to 600 “links” between the tar­get genes.

Just a sin­gle drop from a bio­log­i­cal sam­ple such as sali­va or blood can poten­tial­ly be test­ed in par­al­lel, so that mul­ti­ple dis­eases can be test­ed for in one sit­ting.

But the team has also demon­strat­ed that they are able to trans­form the test­ing solu­tion into a pow­der, mak­ing it light and far eas­i­er to ship than solu­tions, which degrade over time. Pow­der can be stored for years at a time, and offers hope that the tech­nol­o­gy can be devel­oped into effi­cient, cheap, over-the-counter tests for dis­eases such as HIV and malar­ia for devel­op­ing coun­tries, where access to portable diag­nos­tics is a neces­si­ty.

“We’ve now put all the pieces togeth­er,” says Chan.


The Insti­tute of Bio­ma­te­ri­als and Bio­med­ical Engi­neer­ing (IBBME) is an inter­dis­ci­pli­nary unit sit­u­at­ed between three Fac­ul­ties at the Uni­ver­si­ty of Toron­to: Applied Sci­ence and Engi­neer­ing, Den­tistry and Med­i­cine. The Insti­tute pur­sues research in four areas: neur­al, sen­so­ry sys­tems and reha­bil­i­ta­tion engi­neer­ing; bio­ma­te­ri­als, tis­sue engi­neer­ing and regen­er­a­tive med­i­cine; mol­e­c­u­lar imag­ing and bio­med­ical nan­otech­nol­o­gy; med­ical devices and clin­i­cal tech­nolo­gies.


For more infor­ma­tion, con­tact:

Erin Vol­lick
Com­mu­ni­ca­tions Offi­cer
Insti­tute of Bio­ma­te­ri­als and Bio­med­ical Engi­neer­ing (IBBME)
Office: 416–946-8016