Wednesday, July 14, 2010

Plasmonic Structured Illumination Microscopy

Another super resolution imaging method is reported in Nanoletters. Click here to read the paper.

We propose a super resolution imaging technique called plasmonic structured illumination microscopy (PSIM), which combines the structured illumination microscopy technique with the tunable surface plasmon interference. Because of the high-resolution enabled by using surface plasmon interference as an illumination source, PSIM possesses higher image resolving power compared with conventional structured illumination microscopy. To demonstrate the technique, we present two specific types of plasmonic structure designs for PSIM. The final images from the simulations show 3-fold and 4-fold resolution improvement compared with conventional epi-fluorescence microscopy.

Saturday, July 10, 2010

Combining digital scanned laser light-sheet fluorescence microscopy with incoherent structured-illumination microscopy

A high-contrast imaging method is introduced to visualize nontransparent objects by combining two powerful techniques(digital scanned laser light-sheet fluorescence microscopy with incoherent structured-illumination microscopy).

Here is the summary of the novel imaging method that is reported in Nature Methods July 2010 issue:
Recording light-microscopy images of large, nontransparent specimens, such as developing multicellular organisms, is complicated by decreased contrast resulting from light scattering. Early zebrafish development can be captured by standard light-sheet microscopy, but new imaging strategies are required to obtain high-quality data of late development or of less transparent organisms. We combined digital scanned laser light-sheet fluorescence microscopy with incoherent structured-illumination microscopy (DSLM-SI) and created structured-illumination patterns with continuously adjustable frequencies. Our method discriminates the specimen-related scattered background from signal fluorescence, thereby removing out-of-focus light and optimizing the contrast of in-focus structures. DSLM-SI provides rapid control of the illumination pattern, exceptional imaging quality and high imaging speeds. We performed long-term imaging of zebrafish development for 58 h and fast multiple-view imaging of early Drosophila melanogaster development. We reconstructed cell positions over time from the Drosophila DSLM-SI data and created a fly digital embryo.

Friday, July 9, 2010

Subnanometer Single-molecule Analysis

Over the last decade, Sub-diffraction measurement techniques have achieved nanometer resolution using stochastic processes of switchable molecules. Recently, Steven Chu and his research group demonstrated subnanometer localization, registration and distance measurements using closed-loop feedback control systems. Click here to see the recent report published in Nature.

Thursday, July 8, 2010

Single-molecule ELISA

More sensitive biomarker detection in blood requires single protein molecule screening for diagnostic purposes. Microscopic beads with specific antibodies provide flexibility to detect low-abundance proteins in blood. Conventional ELISA can work with an ensemble of proteins linked with antibodies, however, analyzing single proteins is needed for low concentration targets in blood. Towards this end, Quanterix Corporation introduced a technology that can isolate single beads with 50-fl reaction chambers, which also are monitored by fluorescent imaging. They demonstrated the detection of as few as ~10–20 enzyme-labeled complexes in 100 μl of sample (~10−19 M) and routinely allowed detection of clinically relevant proteins in serum at concentrations (<10−15 M) much lower than conventional ELISA

Please check out the recent report in Nature Biotechnology on Single-molecule ELISA.

4D Ultrafast Electron Microscopy

Electron microscopy has been extensively used for cell biology to explain biological processes. But the problem is that the technique is quite invasive (i.e sample requires metal coating) and it requires long exposure times to average fast fluctuations. Recently, Ahmet Zewail and his research group introduced a microscopy technique that can monitor nanometer structures with femtosecond resolution. More importantly, this method mitigates the problems of cell labeling and challenging sample preparation steps.

Researcher called this technology as photon-induced, near-field electron microscopy(PINEM), where they demonstrate the performance of this system initially to image carbon nanotubes and silver nanowires. Click here to read Nature PINEM paper.

Recently, they also used this method to image unstained e-coli with an enhanced contrast and protein vehicles. Click here to read the PNAS Report on Biological Imaging.

This microscope is also commercialized by the company FEI.