For the first time, scientists have used beams of light to manipulate lipid rafts in artificial cell membranes.
Lipid rafts are domains, or areas, of protein and lipid (fats) which float freely in cell membranes – the protein and lipid layer that surrounds a cell.
These structures, which float in the membranes like icebergs, play important but mysterious roles in cellular signalling that aren’t yet fully explained. However until now, our ability to study them has been limited – largely because we haven’t been able to move or manipulate them.
Now, new research from Imperial College London has demonstrated that optical tweezers, the technology that won 2018’s Nobel Prize in Physics, can move, melt, scatter, and crystalise artificial lipid rafts when beamed at artificial cell membranes. These artificial rafts are thought to be linked to the lipid rafts present in biological cell membranes.
The authors say their findings could improve our understanding of the role of lipid rafts in key biological processes like cellular communication and their link to diseases. Lead author Dr Yuval Elani, of Imperial’s Department of Chemistry, said: “These light tweezers have illuminated a new path of research. Now we can manipulate these icebergs, we can discover so much more.”
The research is published in Nature Communications Chemistry.
To carry out the study, the researchers created artificial cell membranes containing lipid rafts on glass slides. Under a microscope, they shone optical tweezer lasers at the membranes.
When they switched on the laser and moved the beam, they found the lipid rafts moved with them within the membrane.
They also focused the laser’s heat directly onto the rafts to melt them, before they scattered into smaller pieces. They then turned off the laser to find the scattered pieces came together again in a crystal-like shape.
Dr Elani said: “We altered the laser’s power to deliver different levels of heat of the system, and melted domains which had different melting temperature due to their different lipid composition. This is a quick and easy way to determine the melting temperature of domains.”
Dr Elani added: “Optical tweezers have previously been used to study a host of cellular processes – from the folding of proteins, to the action of ribosomes and manipulating whole cells. Our technologies pave the way for a deep understanding of the underlying biophysics of lipid rafts and domains, and of their biological significance”.
Co-author Professor Oscar Ces, also from Imperial’s Department of Chemistry, said: “In 2018, Arthur Ashkin won the 2018 Nobel Prize in Physics for using optical tweezers to grab particles, atoms, molecules, and living cells with their laser beam ‘fingers’. We have now discovered yet another function of these fascinating light beams.”
The authors say to gain deeper insights into how lipid rafts affect disease, they need to develop new hardware to fine tune the technique. Next, they will try to apply the technique to biological membranes – ones that aren’t manmade. They hope their next stage of research will further improve our understanding of these mysterious lipid rafts.
This article has been republished from materials provided by Imperial College London. Note: material may have been edited for length and content. For further information, please contact the cited source.
Reference: Mark S. Friddin, Guido Bolognesi, Ali Salehi-Reyhani, Oscar Ces and Yuval Elani. 2019. Direct manipulation of liquid ordered lipid membrane domains using optical traps. Nature Communications Chemistry. http://dx.doi.org/10.1021/acs.analchem.8b03169.