Navigation Links
Tiny probes shine brightly to reveal the location of targeted tissues

Called BRIGHTs, the tiny probes described in the online issue of Advanced Materials on Nov. 15, bind to biomarkers of disease and, when swept by an infrared laser, light up to reveal their location.

Tiny as they are, the probes are exquisitely engineered objects: gold nanoparticles covered with molecules called Raman reporters, in turn covered by a thin shell of gold that spontaneously forms a dodecahedron.

The Raman reporters are molecules whose jiggling atoms respond to a probe laser by scattering light at characteristic wavelengths.

The shell and core create an electromagnetic hotspot in the gap between them that boosts the reporters' emission by a factor of nearly a trillion.

BRIGHTs shine about 1.7 x 1011 more brightly than isolated Raman reporters and about 20 times more intensely than the next-closest competitor probe, says Srikanth Singamaneni, PhD, assistant professor of mechanical engineering and materials science in the School of Engineering & Applied Science at Washington University in St. Louis.

Goosing the signal from Raman reporters

Singamaneni and his postdoctoral research associate Naveen Gandra, PhD, tried several different probe designs before settling on BRIGHTS.

Singamaneni's lab has worked for years with Raman spectroscopy, a spectroscopic technique that is used to study the vibrational modes (bending and stretching) of molecules. Laser light interacts with these modes and the molecule then emits light at higher or lower wavelengths that are characteristic of the molecule,

Spontaneous Raman scattering, as this phenomenon is called, is by nature very weak, but 30 years ago scientists accidently stumbled on the fact that it is much stronger if the molecules are adsorbed on roughened metallic surfaces. Then they discovered that molecules attached to metallic nanoparticles shine even brighter than those attached to rough surfaces.

The intensity boost from surface-enhanced Raman scattering, or SERS, is potentially huge. "It's well-known that if you sandwich Raman reporters between two plasmonic materials, such as gold or silver, you are going to see dramatic Raman enhancement," Singamaneni says.

Originally his team tried to create intense electromagnetic hot spots by sticking smaller particles onto a larger central particle, creating core-satellite assemblies that look like daisies.

"But we realized these assemblies are not ideal for bioimaging," he says, "because the particles were held together by weak electrostatic interactions and the assemblies were going to come apart in the body."

Next they tried using something called Click chemistry to make stronger covalent bonds between the satellites and the core.

"We had some success with those assemblies," Singamaneni says, "but in the meantime we had started to wonder if we couldn't make an electromagnetic hot spot within a single nanoparticle rather than among particles.

"It occurred to us that if we put Raman reporters between the core and shell of a single particle could we create an internal hotspot."

That idea worked like a charm.

A rainbow of probes carefully dispensing drugs?

The next step, says Singamaneni, is to test BRIGHTS in vivo in the lab of Sam Achilefu, PhD, professor of radiology in the School of Medicine.

But he's already thinking of ways to get even more out of the design.

Since different Raman reporter molecules respond at different wavelengths, Singamaneni says, it should be possible to design BRIGHTS targeted to different biomolecules that also have different Raman reporters and then monitor them all simultaneously with the same light probe.

And he and Gandra would like to combine BRIGHTS with a drug container of some kind, so that the containers could be tracked in the body and the drug and released only when it reached the target tissue, thus avoiding many of the side effects patients dread.

Good things, as they say, come in small packages.


Contact: Diana Lutz
Washington University in St. Louis

Related biology news :

1. The shape of things to come: NIST probes the promise of nanomanufacturing using DNA origami
2. Not-so-precious: Stripping gold from AFM probes allows better measurement of picoscale forces
3. Rice University researchers optimize photoluminescent probes to study DNA and more
4. New study shines light on barriers to diabetes care in NYC Bangladeshi community
5. Research reveals first evidence of hunting by prehistoric Ohioans
6. Studies reveal structure of EV71, a virus causing childhood illnesses
7. Researchers reveal how a single gene mutation leads to uncontrolled obesity
8. Study reveals how monarch butterflies recolonize northern breeding range
9. Circadian rhythms have profound influence on metabolic output, UCI study reveals
10. Unexpected discovery reveals a new mechanism for how the cerebellum extracts signal from noise
11. Ancient civilizations reveal ways to manage fisheries for sustainability
Post Your Comments:
Related Image:
Tiny probes shine brightly to reveal the location of targeted tissues
(Date:11/9/2015)... SAN JOSE, Calif. , Nov. 9, 2015 /PRNewswire/ ... of human interface solutions, today announced broader entry into ... of vehicle-specific solutions that match the pace of consumer ... drivers, and biometric sensors are ideal for the automotive ... the vehicle. Europe , ...
(Date:10/29/2015)... 29, 2015   MedNet Solutions , an innovative ... of clinical research, is pleased to announce that it ... (MHTA) as one of only three finalists for a ... Small and Growing" category. The Tekne Awards honor ... superior technology innovation and leadership. iMedNet™ ...
(Date:10/29/2015)... ANN ARBOR, Mich. , Oct. 29, 2015 ... with Eurofins Genomics for U.S. distribution of its ... DNA-seq kit and Rubicon,s new ThruPLEX Plasma-seq ... DNA to enable the preparation of NGS libraries ... in plasma for diagnostic and prognostic applications in ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... November 25, 2015 The ... is a professional and in-depth study on the ...      (Logo: ) , ... industry including definitions, classifications, applications and industry chain ... the international markets including development trends, competitive landscape ...
(Date:11/24/2015)... Nov. 24, 2015 Halozyme Therapeutics, Inc. (NASDAQ: HALO ... New York on Wednesday, December 2 at ... , president and CEO, will provide a corporate overview. ... at 1:00 p.m. ET/10:00 a.m. PT . ... will provide a corporate overview. --> th Annual ...
(Date:11/24/2015)... RALEIGH, N.C. , Nov. 24, 2015  Clintrax Global, Inc., ... Raleigh, North Carolina , today announced that the company has ... earnings represented a 391% quarter on quarter growth posted for Q3 ... Kingdom and Mexico , with the ... place in December 2015. --> United Kingdom ...
(Date:11/24/2015)... New York , November 24, 2015 ... to a recent market research report released by Transparency ... projected to expand at a CAGR of 17.5% during ... "Non-invasive Prenatal Testing Market - Global Industry Analysis, Size, ... estimates the global non-invasive prenatal testing market to reach ...
Breaking Biology Technology: