Nanopositioner for 3-D tracking and super resolution microscopy

Mad City Labs announced its new Nano-LPQ piezo nanopositioner at the SPIE Optics + Photonics show. Designed specifically for microscopy, it is ideal for 3-D particle tracking and super resolution microscopy applications. The XYZ positioner has a low profile and  75 x 75 x 50 micron travel with picometer position noise under closed loop control. It has the same millisecond response times in XYZ, an integrated sample holder, analog and digital control with added scan synchronization features, and is compatible with LabView, C++, and major image and automation software. Mad City Labs’ Nano-Route3D software is included. 

More information:e-mail: sales@madcitylabs.com.

Wednesday at Microscopy and Microanalysis

Things seemed a bit busier today at the Microscopy and Microanalysis show. People's booths were full, and even the talks had more people. 

I went to some talks on live cell imaging this morning. Here are the links to my posts from those:

Researchers from Enzo Life Sciences in Farmingdale, NY have been developing a new red fluorescence molecular probe for detecting phospholipidosis occurring in lysosomes.

Hongwei Duan from Emory University and Georgia Tech presented self-assembled nanoparticles that he, Shuming Nie, and their colleagues have been developing. These particles are designed to act as a cancer therapy as well as an imaging probe.

I attended talks on breaking the optical microscopy diffraction barrier this afternoon. The room was pretty full for these talks. Here are the links to those posts:

Jian Yong Tang from Howard Hughes Medical Institute presented a way to add the third dimension to super-resolution imaging.

Alipasha Vaziri from the Howard Hughes Medical Institute’s Janelia Farm Research Campus is working on improving super-resolution microscopy by acquiring 3D images of thick biological samples. 

I would love to see your comments on the posts. 

Fluorophore blinking harnessed for super-resolution fluorescence microscopy

Most fluorophores naturally switch between fluorescent and dark states. This blinking can be problematic for some types of imaging, but researchers at Ludwig-Maximilians-Universität in Munich, Germany have harnessed the blinking to accomplish super-resolution fluorescence microscopy.

Other researchers have used photoswitchable fluorophores for high-resolution imaging, but the technique published in a recent issue of PNAS overcomes some of the limitations of previous methods by working in the presence of oxygen and using ordinary fluorophores. The Ludwig-Maximilians researchers achieved precise control of oxazine dye fluorescence by adding or removing reductant or oxidant, which switched the flourophore between stable fluorescent and nonfluorescent (dark) states. Depending on the switching rate, they achieved 400 and 3,000 switching cycles before irreversible photodestruction.

Subdiffraction resolution microscopy can be accomplished if most fluorophores in a diffraction-limited area are in the dark state. A sensitive camera resolves the location of any remaining fluorescing fluorophores. Using their method to control the dark state of fluorophores, the researchers imaged actin filament and actin filament bundles in fixed cells. The resulting images show many details not resolvable in the total internal reflection fluorescence images of the same area. Such fine control of fluorophore states could also be useful for activating molecular switches for nanotechnology devices.

Research paper:
Jan Vogelsang, Thorben Cordes, Carsten Forthmann, Christian Steinhauer, and Philip Tinnefeld, Controlling the fluorescence of ordinary oxazine dyes for single-molecule switching and superresolution microscopy, PNAS 2009

STED microscopy illumination used in photolithography

In a post last month, I questioned what it would take for microscopy methods that overcome the diffraction limit to gain more use. I may have found a partial answer to my question in a research paper published last week in Science Express.

The key to more powerful computers and increased data storage is patterning smaller details, but the standard photolithography techniques used for this have reached optical limitations. To pattern features without the diffraction-limit constraint of standard techniques, Timothy Scott and colleagues from the University of Colorado at Boulder turned to an irradiation technique similar to one used by stimulated emission-depletion (STED) microscopy.

In simple terms, STED microscopy confines fluorescence emission to a point smaller than the diffraction limit by using a pulsed beam to excite the fluorophore, and overlapping it with the focal point of a pulsed, Gauss-Laguerre (donut-shaped) mode beam. The two sets of pulses must reach the focal plane simultaneously so that the Gauss-Laguerre beam instantly de-excites potentially excited molecules by stimulated emission. 

Similarly, the University of Colorado researchers’ single-photon lithography method uses a central beam that links polymer chains together and a surrounding Gauss-Lagueer mode beam that inhibits action in the surrounding area. The size of patterned features is limited by the contrast between the central beam and the Gauss-Laguerre beam. The technique doesn’t require an expensive laser or come with the speed limitations of two-photon-based alternatives to standard photolithography.

While this may not be a direct use of STED microscopy, it shows how science can cross disciplines, sometimes finding even more practical or important uses. 

Research paper:
Two-Color Single-Photon Photoinitiation and Photoinhibition for Subdiffraction Photolithography, Timothy F. Scott, Benjamin A. Kowalski, Amy C. Sullivan, Christopher N. Bowman, and Robert R. McLeod, Published online April 9 2009; 10.1126/science.1167610 (Science Express Reports)

ACS Spring Meeting

The Spring '09 meeting of the American Chemical Society is currently underway in Salt Lake City. With the theme "Nanoscience: Challenges for the Future," there's sure to be some interesting microscopy research being presented.

Here are a few of my picks:

• Studying spores with atomic force microscopy (AFM) – Alexander Malkin from the Lawrence Livermore National Laboratory discusses how in vitro AFM can be used to study microbial systems. For example, it can be used for directly visualizing the structural dynamics of single germinating bacterial spores. Yet another example of AFM's usefulness in biology.
• Organic photovoltaics under the microscope – Researchers from the University of Texas at Austin simultaneously collected near-field scanning optical microscopy (NSOM) images of transmission, fluorescence, and photocurrent to examine factors limiting efficiency of an organic photovoltaic device. Organic photovoltaics are one of the leading technologies for solar power.
• Mixing microscopy and food– Researchers at Auburn University have used AFM to study of the nanostructure of food grade gelatin and polysaccharide water absorbents as well as for rapid identification of microorganisms tied to food safety. With all the food safety problems in the news, techniques to make sure food is safe before it gets to consumers are needed.
• MEMS-based heater for electron microscopy - Researchers from Oak Ridge National Laboratory together with Protochips Inc. are developing an in-situ MEMS-based heater chip that will aid in electron microscopy imaging of mononuclear catalytic species such as Au/Fe2O3 and Ir/MgO.

The conference included several talks on optical methods that overcome the diffraction limit:
Fluorescence photoactivation localization microscopy (FPALM)
Stochastic optical reconstruction microscopy (STORM)
Using fusions to EYFP
These all seem really nifty to me, but I've been hearing about various techniques to overcome the diffraction limit for several years (maybe more than several). What will it take for these techniques to find more use?