<figcaption>Figure 2. <i>E. coli</i> BL21 cells transformed with Sil_Sdom, provided with silicic acid and were UV sterilized and subsequently imaged by with SEM. </figcaption>
Imaging cells is essential for understanding life at the smallest scale and fighting cellular diseases like cancer. Imaging often relies on fluorescence, but fluorescent proteins have some drawbacks, such as their wide spectrum and low intensity.
Our biolasers will provide an accurate, safe and biological way to improve this.
Fluorescence is the ability of a molecule to take up the energy of a photon and release it again, which makes the molecule light up. Lasing works with the same principle as fluorescence, but now the light source is put between mirrors. The photons keep ‘bouncing’, increasing the energy of the system. When the light gets a certain power, the photons can escape in the form of a laser beam.
A biolaser is achieved by trapping fluorescent proteins inside a reflective agent. We have chosen two reflective agents: bioglass (polysilicate) and bioplastic (PHB). By covering a cell with polysilicate, the photons can resonate inside the cell, making a whole-cell laser. The polysilicate is synthesized by an enzyme called silicatein, which is expressed on the cell wall by fusion to membrane proteins. By filling a cell with PHB, which forms intracellular granules, the photons can resonate inside a part of the cell, making an intracellular laser. The PHB is synthesized after expressing the pha-operon. By fusing the GFP to the PHB synthase, the GFP is relocated into the PHB granules.
Microlenses are an emerging field in technology and have a ton of applications, including high-tech cameras, chips, solar panels and research & imaging techniques. However, they are expensive, hard to fabricate and the production uses heavy chemicals and high temperatures, so it is bad for the environment.
Our biological microlens will be cheap, easy to make and environmentally friendly.
When we cover a cell with polysilicate, using the enzyme silicatein, we are able to make a biological microlens. By overexpressing either the transcriptional regulator bolA or the cell division inhibitor sulA we can play with cell morphology and investigate optical properties. These enlarged cells can also be used in the lasing experiments. The single cell will be able to diffract light as a single microlens. When we make a grid of lenses, a microlens array, we can use the lens for a coating for solar panels, thin lightweight cameras with high resolution or 3D screens.
