Research Roundup: Nanoantennas slow light, regrowing human cartilage, new microscope to see ocean microorganisms

Aug. 26, 2020, 8:25 p.m.

Each week, The Daily’s Science & Tech section produces a roundup of the most exciting and influential research happening on campus or otherwise related to Stanford. Here’s our digest for the week of Aug 16 – Aug 22.

Nanoantennas can slow light photons and manipulate their path

Ultrathin silicon nanoantennas can slow light and allow scientists to redirect light photons at will, a study published on Aug. 17 in “Nature Nanotechnology” found.

Light exchanges information at extremely high speeds, but has a low chance of interacting with molecules when it passes through material. If light could be manipulated and slowed down, it has the potential to detect viruses like SARS-CoV-2.

“We’re essentially trying to trap light in a tiny box that still allows the light to come and go from many different directions,” materials science and engineering postdoctoral researcher Mark Lawrence told Stanford News. “It’s easy to trap light in a box with many sides, but not so easy if the sides are transparent — as is the case with many silicon-based applications.”

The team of researchers developed “high-quality-factor” resonators from extremely thin layers of silicon. This nanostructure traps light efficiently, and researchers can then direct an electron microscope “pen” to draw out nanoantenna patterns for multiple applications, including SARS-CoV-2 detection, light detection and ranging (LIDAR) or virtual reality technology.

“High-quality-factor” resonators can be used for biosensing tiny molecules. An individual molecule is too small to observe, but scattering effects produced by light that passes over the molecule thousands of times are observable to scientists.

“Our technology would give an optical readout like the doctors and clinicians are used to seeing,” materials science and engineering associate professor Jennifer Dionne told Stanford News. “But we have the opportunity to detect a single virus or very low concentrations of a multitude of antibodies owing to the strong light-molecule interactions.”

Regrowing the body’s natural cartilage in joints using microfracturing

Researchers have developed a method to regrow cartilage in the body’s joints, a study published on Aug. 17 in “Nature Medicine” reports.

“Cartilage has practically zero regenerative potential in adulthood, so once it’s injured or gone, what we can do for patients has been very limited,” assistant professor of surgery Charles K.F. Chan told Stanford Medicine News. “It’s extremely gratifying to find a way to help the body regrow this important tissue.”

The findings suggest that microfracturing, a process that involves drilling small holes in the joint’s surface, can promote the growth of new tissue similar to cartilage.

The team found that after a microfracturing procedure, adding the molecule bone morphogenetic protein 2 (BMP2) would initiate bone formation. Next, adding vascular endothelial growth factor (VEGF) would create cartilage similar to natural cartilage.

“What we ended up with was cartilage that is made of the same sort of cells as natural cartilage with comparable mechanical properties, unlike the fibrocartilage that we usually get,” Chan told Stanford Medicine News.

Rotating microscope provides new microorganism insight into ocean life

A newly developed rotating microscope allows scientists to study the behavior and molecular processes of microorganisms like plankton in the ocean, a study published on Aug. 17 in “Nature Methods” reports.

“This is a completely new way of studying life in the ocean,” sixth-year mechanical engineering Ph.D. student Deepak Krishnamurthy told Stanford News.

The team built a vertically tracking microscope for microorganisms, dubbed a “hydrodynamic treadmill.” As the microorganism moves up or down, the microscope rotates and tracks its vertical movements in the lab-made water column. The rotation of the water column enables microorganisms to move in an extreme vertical direction, simulating how these microorganisms travel in the ocean.

For example, when observing the larvae of marine creatures like the bat star, sea cucumber and Pacific sand dollar along the Californian coast, researchers found that the creatures employ various techniques to move across the sea.

“To truly understand biological processes at play in the ocean at smallest length scales, we are excited to both bring a piece of the ocean to the lab, and simultaneously bring a little piece of the lab to the ocean,” bioengineering associate professor Manu Prakash told Stanford News.

Contact Derek Chen at derekc8 ‘at’

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