St Andrews (UK) – The transfection of genes and injection of drugs into mammalian cells are among the most important research tools in modern molecular biology. A variety of techniques have been developed to introduce foreign material into the cytoplasm of cells. Laser induced membrane poration has proven to be an attractive alternative to classical methods. These laser methods now proliferate from the optical benches of biophysics departments towards advanced molecular biology research laboratories. However, their broader application still requires the development of robust, consistent and user-friendly systems that do not depend on the experience of an operator.
Maciej Antkowiak and his colleagues from the University of St Andrews (UK) now demonstrate the advantages of a dynamic diffractive optical element, namely a spatial light modulator (SLM) which acts as a dynamic diffractive optical element, providing full control over the lateral and axial positioning of the beam with submicron precision. It alleviates the key problems of beam positioning on the membrane and is a key step towards high throughput transfection of adherent cells.
They were able to show that the method provides a user friendly environment. It not only makes the poration process more consistent and repeatable but enables a controlled application of a timed sequence of doses at various axial and lateral positions, which increases the chances of hitting the membrane. If a triple axial sequence of irradiation is used instead of a single dose the percentage of viable optoinjected cells can be doubled.
By using a special software interface, a user may simply point at the cell within the field of view and a predefined dose can be applied. If this is accompanied by fluorescent imaging a cell selective co-transfection can be performed based on earlier gene expression, which paves the way for a multi-step gene therapy. Moreover, if a high throughput transfection is a priority, an unassisted raster scan can be executed at the average speed of 1 cell per second.
The sub-micron beam positioning precision and the possibility of fast dynamic reconfiguration could also be used in cell and tissue nanosurgery. (DOI: 10.1002/jbio.201000052)
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