Asian Scientist (Aug. 15, 2013) – A team of scientists in South Korea have developed the most precise method ever used to insert DNA into cells. The method combines two high-tech laboratory techniques and allows the researchers to precisely poke holes on the surface of a single cell with a high-powered “femtosecond” laser and then gently tug a piece of DNA through it using “optical tweezers,” which draw on the electromagnetic field of another laser.
The applications of gene therapy and genetic engineering are broad: everything from pet fish that glow red to increased crop yields worldwide to cures for many of the diseases that plague humankind. But realizing them always starts with solving the same basic scientific question—how to “transfect” a cell by inserting foreign DNA into it.
Many methods already exist for doing this, but they tend to be clumsy and destructive, not allowing researchers to precisely control how and when they insert the DNA or requiring them to burn through large numbers of cells before they can get it into one.
Now, the team’s laser-based approach, reported in Biomedical Optics Express, allows unprecedented precision and control of DNA insertion at the single-cell level.
To manipulate the foreign DNA, the scientists used optical tweezers, which essentially tweaks a laser beam whose electromagnetic field can grab hold of and transport a plasmid-coated particle.
The researchers first moved the particle to the surface of the cell membrane. Guided by the trapped particle, they then created a tiny pore in the cell membrane using an ultra-short laser pulse from a femtosecond laser. While another laser beam detected the exact location of the cell membrane, they pushed the particle through the pore with the tweezers.
Using this technique, the scientists were able to ease a microparticle right up to the pore in the membrane and drop it into the cell, like a golfer sinking an easy putt.
To determine whether their method had succeeded, the researchers inserted plasmids carrying a gene that codes for a green fluorescent protein.
Once inside the cell, the gene became active and the cell’s machinery began producing the protein. The researchers could then detect the green glow using a fluorescence microscope.
They found that approximately one in six of the cells they studied became transfected. This rate is lower than that recorded for some other methods, but those are less precise and involve many cells at a time.
The article can found at: Waleed et al. (2013) Single-Cell Optoporation And Transfection Using Femtosecond Laser And Optical Tweezers.
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Source: OSA; Image: Gwangju Institute of Science and Technology.
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