Scientists have successfully reanimated fish that were frozen as part of a cryopreservation project. Though the process was not perfect — most of the fish died within the first hour of being reanimated — there were statistically notable instances of survival that highlighted the potential of this new cryopreservation technique. How did the researchers pull it off? By using very small particles of gold and laser beams.
The technology was recently detailed in ACS Nano, where researchers explain that a combination of gold and lasers were used to bring these fish embryos back to life. Though cryopreservation is nothing new, the technology is still in its infancy and attempts at preserving life are largely unsuccessful. The difficultly comes from damaging water crystals that form if the preserved cells are frozen or thawed too slowly.
According to the study, researchers injected zebrafish embryos with cryoprotectants, then cryogenically froze them at a speed rapid enough to avoid destructive water crystal formation. This process has been achieved with success many times in the past; thawing the embryos while preserving life is the point where failure arises. This time around, though, scientists used gold nanorods mixed in with the propylene glycol cryoprotectant.
Once the gold nanorods were injected within the embryos, the fish embryos were rapidly cooled into a state of frozen preservation…with the nanorods now inside of the cells. To thaw the frozen embryos rapidly enough, scientists used a 1064nm laser and pulsed it for a single millisecond onto the gold within the embryos. This excited the nanorods, generating heat within the cells that rapidly warmed them to the proper temperature.
When using other warming methods on the control embryos, the scientists experienced 100% failure in terms of survival. When using this gold nanorods method, though, the researchers saw 31-percent success within the first hour, a figure that dropped to 10-percent at the 24hr mark. By the end of those 24hrs, the surviving reanimated fish embryos showed movement.