Navigation Links
Light twists rigid structures in unexpected nanotech finding

ANN ARBOR, Mich.---In findings that took the experimenters three years to believe, University of Michigan engineers and their collaborators have demonstrated that light itself can twist ribbons of nanoparticles.

The results are published in the current edition of Science.

Matter readily bends and twists light. That's the mechanism behind optical lenses and polarizing 3-D movie glasses. But the opposite interaction has rarely been observed, said Nicholas Kotov, principal investigator on the project. Kotov is a professor in the departments of Chemical Engineering, Biomedical Engineering and Materials Science and Engineering.

While light has been known to affect matter on the molecular scale---bending or twisting molecules a few nanometers in size---it has not been observed causing such drastic mechanical twisting to larger particles. The nanoparticle ribbons in this study were between one and four micrometers long. A micrometer is one-millionth of a meter.

"I didn't believe it at the beginning," Kotov said. "To be honest, it took us three and a half years to really figure out how photons of light can lead to such a remarkable change in rigid structures a thousand times bigger than molecules."

Kotov and his colleagues had set out in this study to create "superchiral" particles---spirals of nano-scale mixed metals that could theoretically focus visible light to specks smaller than its wavelength. Materials with this unique "negative refractive index" could be capable of producing Klingon-like invisibility cloaks, said Sharon Glotzer, a professor in the departments of Chemical Engineering and Materials Science and Engineering who was also involved in the experiments. The twisted nanoparticle ribbons are likely to lead to the superchiral materials, the professors say.

To begin the experiment, the researchers dispersed nanoparticles of cadmium telluride in a water-based solution. They checked on them intermittently with powerful microscopes. After about 24 hours under light, the nanoparticles had assembled themselves into flat ribbons. After 72 hours, they had twisted and bunched together in the process.

But when the nanoparticles were left in the dark, distinct, long, straight ribbons formed.

"We discovered that if we make flat ribbons in the dark and then illuminate them, we see a gradual twisting, twisting that increases as we shine more light," Kotov said. "This is very unusual in many ways."

The light twists the ribbons by causing a stronger repulsion between nanoparticles in them.

The twisted ribbon is a new shape in nanotechnology, Kotov said. Besides superchiral materials, he envisions clever applications for the shape and the technique used to create I it. Sudhanshu Srivastava, a postdoctoral researcher in his lab, is trying to make the spirals rotate.

"He's making very small propellers to move through fluid---nanoscale submarines, if you will," Kotov said. "You often see this motif of twisted structures in mobility organs of bacteria and cells."

The nanoscale submarines could conceivably be used for drug-delivery and in microfluidic systems that mimic the body for experiments.

This newly-discovered twisting effect could also lead to microelectromechanical systems that are controlled by light. And it could be utilized in lithography, or microchip production.

Glotzer and Aaron Santos, a postdoctoral researcher in her lab, performed computer simulations that helped Kotov and his team better understand how the ribbons form. The simulations showed that under certain circumstances, the complex combination of forces between the tetrahedrally-shaped nanoparticles could conspire to produce ribbons of just the width observed in the experiments. A tetrahedron is a pyramid-shaped, three-dimensional polyhedron.

"The precise balance of forces leading to the self-assembly of ribbons is very revealing," Glotzer said. "It could be used to stabilize other nanostructures made of non-spherical particles. It's all about how the particles want to pack themselves."


Contact: Nicole Casal Moore
University of Michigan

Related biology technology :

1. Dendreon Announces Publication of Phase 1 Study Highlighting Immunologic and Clinical Activity of Lapuleucel-T (Neuvenge(R)) in Advanced Breast Cancer Patients
2. ImmuneRegen BioSciences Files 8-K that Highlights Enclosed Shareholder Letter Discussing Recent Achievements and Outlook
3. Safety Profile of TAXUS(R) Liberte(TM) Stent System Highlighted in Worlds Largest Stent Registry
4. Stimuvax(R) Phase II data highlight three-year survival results for patients with non-small cell lung cancer
5. Three Studies by Independent Scientists Highlighting Pressure Cycling Technology (PCT) to be Presented this Week at the British Mass Spectrometry Societys 29th Annual Meeting
6. Access Highlighted in Recent BusinessWeek Article
7. Lighting the Onco-Pipeline, Stem Cell Cancer, and More at Global Cancer Congress, January 28-29, 2008, Tampa
8. Highlights of Economic and Business Growth in the Tampa Bay Region
9. Respironics Acquires Apollo Light Systems, Inc., Expands into Circadian Rhythm Device-Based Therapy Market
10. Americas Heartland Launches Third Season Highlighting Contributions of American Farmers and Ranchers
11. CU researchers shed light on light-emitting nanodevice
Post Your Comments:
Related Image:
Light twists rigid structures in unexpected nanotech finding
(Date:6/27/2016)... --  Ginkgo Bioworks , a leading organism design ... awarded as one of the World Economic Forum,s ... innovative companies. Ginkgo Bioworks is engineering biology to ... in the nutrition, health and consumer goods sectors. ... including Fortune 500 companies to design microbes for ...
(Date:6/24/2016)... SAN DIEGO , June 24, 2016 /PRNewswire/ ... that more sensitively detects cancers susceptible to PARP ... individual circulating tumor cells (CTCs). The new test ... of HRD-targeted therapeutics in multiple cancer types. ... therapies targeting DNA damage response pathways, including PARP, ...
(Date:6/24/2016)... (PRWEB) , ... June 24, 2016 , ... Researchers at ... most commonly-identified miRNAs in people with peritoneal or pleural mesothelioma. Their findings are the ... read it now. , Diagnostic biomarkers are signposts in the blood, lung fluid ...
(Date:6/23/2016)... WI (PRWEB) , ... June 23, 2016 , ... ... supplements, is pleased to announce the launch of their brand, UP4™ Probiotics, into ... for over 35 years, is proud to add Target to its list of ...
Breaking Biology Technology:
(Date:6/3/2016)... , June 3, 2016 ... von Nepal hat ... Lieferung hochsicherer geprägter Kennzeichen, einschließlich Personalisierung, Registrierung ... in der Produktion und Implementierung von Identitätsmanagementlösungen. ... Ausschreibung im Januar teilgenommen, aber Decatur wurde ...
(Date:5/24/2016)... superior patient care by providing unparalleled technology to leaders of the medical imaging industry. ... recently added to the range of products distributed by Ampronix. Photo - ... ... ... ...
(Date:5/3/2016)... May 3, 2016  Neurotechnology, a provider of ... MegaMatcher Automated Biometric Identification System (ABIS) , a ... projects. MegaMatcher ABIS can process multiple complex biometric ... combination of fingerprint, face or iris biometrics. It ... and MegaMatcher Accelerator , which have ...
Breaking Biology News(10 mins):