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.
Nanostructures called BRIGHTs seek out biomarkers on cells and then beam brightly to reveal their locations. In the tiny gap between the gold skin and the gold core of the cleaved BRIGHT (visible to the upper left), there is an electromagnetic hot spot that lights up the reporter molecules trapped there.
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’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?
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.
Diana Lutz | EurekAlert!
Spider silk key to new bone-fixing composite
20.04.2018 | University of Connecticut
Diamond-like carbon is formed differently to what was believed -- machine learning enables development of new model
19.04.2018 | Aalto University
Ein computergestütztes Netzwerk zeigt, wie die Ionenkanäle in der Membran von Nervenzellen so verschiedenartige Fähigkeiten wie Kurzzeitgedächtnis und Hirnwellen steuern können
Nervenzellen, die auch dann aktiv sind, wenn der auslösende Reiz verstummt ist, sind die Grundlage für ein Kurzzeitgedächtnis. Durch rhythmisch aktive...
Von einer einzigen Stammzelle zur Vielzahl hochdifferenzierter Körperzellen: Den vollständigen Stammbaum eines ausgewachsenen Organismus haben Wissenschaftlerinnen und Wissenschaftler aus Berlin und München in „Science“ publiziert. Entscheidend war der kombinierte Einsatz von RNA- und computerbasierten Technologien.
Wie werden aus einheitlichen Stammzellen komplexe Körperzellen mit sehr unterschiedlichen Funktionen? Die Differenzierung von Stammzellen in verschiedenste...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Polymer-Leuchtdioden (PLEDs) sind attraktiv für den Einsatz in großflächigen Displays und Lichtpanelen, aber ihre begrenzte Stabilität verhindert die Kommerzialisierung. Wissenschaftler aus dem Max-Planck-Institut für Polymerforschung (MPIP) in Mainz haben jetzt die Ursachen der Instabilität aufgedeckt.
Bildschirme und Smartphones, die gerollt und hochgeklappt werden können, sind Anwendungen, die in Zukunft durch die Entwicklung von polymerbasierten...
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
19.04.2018 | Veranstaltungen
19.04.2018 | Veranstaltungen
17.04.2018 | Veranstaltungen
20.04.2018 | Interdisziplinäre Forschung
20.04.2018 | Physik Astronomie
20.04.2018 | Geowissenschaften