Salk Institute
Hu Cang
Assistant Professor
Waitt Advanced Biophotonics Center
Hu Cang

Assistant Professor
Waitt Advanced Biophotonics Center


Research

Advances in optical engineering now routinely provide researchers with an unprecedented ability to control, manipulate and detect light. Simultaneously, modern manufacturing and fabrication technologies allow unprecedented insights into a new and virtually uninvestigated nano-world. The Cang Laboratory in the Waitt Advanced Biophotonics Center is focused on taking advantage of both these advances to further enhance our ability to manipulate light as a tool to investigate the basic function of biological systems.

One of our primary research aims is to extend the theory of geometric optics to the nanoscale. The goal of this theoretical work is to design a new and novel lens system whose optical resolution will no longer be limited by the wavelength of light. In principle, this "super lens" will enable an optical microscope to reach the same resolution levels as that of an electron microscope. Previously, our group has designed and fabricated novel nano-structures for biological and medical applications. These have included novel nanoparticles that have enhanced the contrast of Spectroscopy-Optical Coherence Tomography (S-OCT), a technique that holds potential as a diagnostic tool for early cancer detection. In addition, our group has fabricated optical antennas that harvest photons from dye molecules, enhancing their brightness by nearly a factor of 1,000. We hope to use these special antennas to monitor conformational changes in a single protein molecule in real-time. We also plan to integrate these optical antennas with our previously developed single-molecule tracking technology to measure how single proteins function and how they are synchronized with other proteins within the complex three-dimensional environment of a living cell.

Lab Positions

We are seeking students or postdocs to join efforts in the development of novel nano-photonics tools for biological and medical studies. Candidates with experience in any of the following areas are highly desired: experimental optics, theoretical or computational optics, and molecular biology or biophysics. Please contact Dr. Hu Cang (hucang@salk.edu) for more information.

"The resolution of a lens is limited to about a quarter of a micrometer, which is a hundred times larger than the size of most biomolecules. The goal of our research is to develop new technologies to break this limit and build a microscope that can visualize biological processes at the single-molecule level."

Advances in optical engineering now routinely provide researchers with an unprecedented ability to control, manipulate and detect light. Simultaneously, modern manufacturing and fabrication technologies allow access to the world at the nanoscale level.

The Cang lab in the Waitt Advanced Biophotonics Center focuses on using these advances to further enhance the ability to manipulate light to explore the molecular basis of life.

The wavelength of light is determined by its interactions with the surrounding medium, and the stronger the interaction, the shorter the wavelength. A microscope that uses short wavelengths can be used to visualize smaller objects. Noble metals, such as gold and silver, exhibit one of the strongest interactions with light, making it possible to use these metals to build super-resolution microscopes.

Cang and his collaborators were the first team to focus light down to a point about the size of a single protein, using aluminum and silver nanodevices. In another study, they revealed that certain nanostructures can shield molecules from photodamage, enabling researchers to extract up to three orders of magnitude more light photons out of dye molecules of the sort used to visualize cellular processes under a microscope.

Cang's group also may have found a way to overcome longstanding limitations on designing microscope lenses. Since the 17th century, lenses have been designed using a "ray tracing" method based on calculating the path of light through a medium. However, the method could not be used for lenses capable of magnifying an object smaller than the wavelength of light. Cang's group showed that it may be possible to circumvent this problem by dividing the design into many parts that could later be reconstructed into a single lens.

The goal of this theoretical work is to design a new lens system whose optical resolution will no longer be limited by the wavelength of light. In principle, this "super lens" will enable an optical microscope to reach the same resolution levels as that of an electron microscope, allowing researchers to zoom in on single molecules in living cells to investigate their biological functions.

Lab Photo

From left: Yu Li, Hu Cang, Ying Hu

Selected Publications

Hu, Y.; Nan, X.; Lippincott-Schwartz, J; Cang, H. Accelerating 3B microscopy with cloudy computation. Nature Methods 2013, (10), 96-97.

Hu Cang; Anna Labno; Changgui Lu; Xiaobo Yin; Ming Liu; Christopher Gladden; Xiang Zhang, Probing the distribution of electromagnetic field of a 15nm sized hotspot by single molecule imaging. Nature 2011, (469), 385

Cang, H.; Xu, C. S.; Montiel, D.; Yang, H., Guiding a confocal microscope by single fluorescent nanoparticles. Opt Lett 2007, 32, (18), 2729-31.

Cang, H.; Wong, C. M.; Xu, C. S.; Rizvi, A. H.; Yang, H., Confocal three dimensional tracking of a single nanoparticle with concurrent spectroscopic readouts. Applied Physics Letters 2006, 88, (22).

Cang, H.; Sun, T.; Li, Z. Y.; Chen, J. Y.; Wiley, B. J.; Xia, Y. N.; Li, X. D., Gold nanocages as contrast agents for spectroscopic optical coherence tomography. Optics Letters 2005, 30, (22), 3048-3050.

Awards and Honors

  • Ray Thomas Edwards Career Development Award, 2013 - 2016
  • Annual Review of Physical Chemistry Award, 2005
  • Franklin Veatch Memorial Fellowship, Stanford University, 2002-2003

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