Fast unthawing using lasers and gold nanopoarticles

The University of Minnesota has made a highly-touted new technology for “cryo-preserving” living biomaterials such as fish embryos available for licensing. Ultimately, the public institution is seeking a commercialization partner for the method hailed as a breakthrough for wildlife conservation and human health research.

In 2017, they provided first-ever reproducible evidence for the successful cryopreservation of zebrafish embryos.

This was the first time a frozen fish embryo had survived to grow after being thawed out from a cryogenic state. Zebrafish are particularly valuable to health researchers because their genomes approximate those of humans closely enough to be used for modelling diseases in lab experiments.

For the health researchers, the ability to cryopreserve zebrafish embryos would be valuable because it would make their studies on human diseases such as muscular dystrophy and melanoma easier to conduct and replicate — they wouldn’t have to work around the fishes’ spawning schedules or contend with “genetic drift” of subsequent generations.

And for wildlife preservations, they can freeze sperm, eggs and embryos. They can safeguard at-risk aquatic species and their genetic diversity, making it possible to bolster the genetic pool and therefore guarantee the health of wild populations years — or even centuries — later.

They overcome a previous roadblock in cryopreserving fish embryos: Due to their large size, traditional ways of thawing them out are too slow and result in the formation of ice crystals which damage them and prevent viability. The key innovation of the U technology addresses that problem with the use of gold nanoparticles, or cylindrical “nanorods,” which are injected into the embryo before freezing.

They essentially act as a “distributed network” of ultra-efficient heaters that generate very fast warming rates when illuminated with an infrared laser, thus avoiding the creation of ice crystals. The nanorods also have low toxicity levels.

ACS Nano – Gold Nanorod Induced Warming of Embryos from the Cryogenic State Enhances Viability

Zebrafish embryos can attain a stable cryogenic state by microinjection of cryoprotectants followed by rapid cooling, but the massive size of the embryo has consistently led to failure during the convective warming process. Here we address this zebrafish cryopreservation problem by using gold nanorods (GNRs) to assist in the warming process. Specifically, we microinjected the cryoprotectant propylene glycol into zebrafish embryos along with GNRs, and the samples were cooled at a rate of 90 000 °C/min in liquid nitrogen. We demonstrated the ability to unfreeze the zebrafish rapidly (1.4 × 107 °C/min) by irradiating the sample with a 1064 nm laser pulse for 1 ms due to the excitation of GNRs. This rapid warming process led to the outrunning of ice formation, which can damage the embryos. The results from 14 trials (n = 223) demonstrated viable embryos with consistent structure at 1 h (31%) and continuing development at 3 h (17%) and movement at 24 h (10%) postwarming. This compares starkly with 0% viability, structure, or movement at all time points in convectively warmed controls (n = 50, p < 0.001, ANOVA). Our nanoparticle-based warming process could be applied to the storage of fish, and with proper modification, can potentially be used for other vertebrate embryos. A well-calibrated millisecond laser pulse can suddenly heat up an embryo by way of the gold distributed throughout it, reheating it at the astonishing rate of 1.4 x 107 °C per minute, an almost unfathomable temperature that is manageable in the quick bursts that the researchers employ.

The results were hot enough—and widely distributed enough—to successfully reheat an entire zebrafish embryo at once.

12 thoughts on “Fast unthawing using lasers and gold nanopoarticles”

  1. Hrm, wasn’t there something similar where they were injecting some kind of material (nanoscale gold also?) into prostate cancer tissue so they could heat just that without chemotherapy to kill the cells? Though I seem to remember that it used some sort of biotargeting to get the nanostructures to the cancer cells. There was also a more macro version where they inserted staple-like objects and somehow heated those. There’s a japanese flash freezing technique where you put tissue in a very high magnetic field and subcool, then cut the field to cause subcooled water in the cells to flash freeze. The mag field wiggles the water to keep it from forming ice crystals, so when it stops, all the water tries to freeze at once. I think it was called CAS and done by ABI-net, who sell it for tissue preservation as well as bulk food freezing (for improved flavor).

    Reply
  2. Hrm wasn’t there something similar where they were injecting some kind of material (nanoscale gold also?) into prostate cancer tissue so they could heat just that without chemotherapy to kill the cells? Though I seem to remember that it used some sort of biotargeting to get the nanostructures to the cancer cells. There was also a more macro version where they inserted staple-like objects and somehow heated those.There’s a japanese flash freezing technique where you put tissue in a very high magnetic field and subcool then cut the field to cause subcooled water in the cells to flash freeze. The mag field wiggles the water to keep it from forming ice crystals so when it stops all the water tries to freeze at once. I think it was called CAS and done by ABI-net who sell it for tissue preservation as well as bulk food freezing (for improved flavor).

    Reply
  3. I imagined it wouldn’t be so easy as just scaling it, given they use infrared radiation and the human body is a poor transmission medium at such wavelengths (it is not completely opaque to it, though). My hunch is that the technologies and observations made on these smaller examples of cryopreservation will serve for lateral or parallel developments later, probably using microwaves or other methods for uniformly giving the energy and for protecting the cells. We usually require some working example to start with, for taking things from there. But I admit that things can stop there for a while, there is no warranty at all that things that work at the micro and mesoscale work at the macroscale.

    Reply
  4. I imagined it wouldn’t be so easy as just scaling it given they use infrared radiation and the human body is a poor transmission medium at such wavelengths (it is not completely opaque to it though).My hunch is that the technologies and observations made on these smaller examples of cryopreservation will serve for lateral or parallel developments later probably using microwaves or other methods for uniformly giving the energy and for protecting the cells.We usually require some working example to start with for taking things from there.But I admit that things can stop there for a while there is no warranty at all that things that work at the micro and mesoscale work at the macroscale.

    Reply
  5. I recall years ago we were doing calculations on ultra-fast heating of cryopreserved tissues using nano-sized thermite bombs… (Just blue sky stuff on a cryonics forum.) and potentially you could reach heating rates so high that the real limit was your skin spalling off due to the rate of thermal expansion causing a shock wave to propagate through the tissue. So I’m not surprised at these results. But this particular research won’t scale to human body size, due to the need to supply the energy from outside.

    Reply
  6. I recall years ago we were doing calculations on ultra-fast heating of cryopreserved tissues using nano-sized thermite bombs… (Just blue sky stuff on a cryonics forum.) and potentially you could reach heating rates so high that the real limit was your skin spalling off due to the rate of thermal expansion causing a shock wave to propagate through the tissue. So I’m not surprised at these results.But this particular research won’t scale to human body size due to the need to supply the energy from outside.

    Reply
  7. One small zebra fish embryo sized step towards cryostasis for larger animals. And a big step towards taking all kinds of egg laying/small larva-having animals to Mars or anywhere. Once we can do it for rodents and such, we will know humans aren’t far away, albeit the obstacles will still be considerable, given this involves surface vs volume effects. But once it exists, we could sleep (or rather reversibly die) our way to the stars.

    Reply
  8. One small zebra fish embryo sized step towards cryostasis for larger animals. And a big step towards taking all kinds of egg laying/small larva-having animals to Mars or anywhere.Once we can do it for rodents and such we will know humans aren’t far away albeit the obstacles will still be considerable given this involves surface vs volume effects.But once it exists we could sleep (or rather reversibly die) our way to the stars.

    Reply
  9. Hrm, wasn’t there something similar where they were injecting some kind of material (nanoscale gold also?) into prostate cancer tissue so they could heat just that without chemotherapy to kill the cells? Though I seem to remember that it used some sort of biotargeting to get the nanostructures to the cancer cells. There was also a more macro version where they inserted staple-like objects and somehow heated those.

    There’s a japanese flash freezing technique where you put tissue in a very high magnetic field and subcool, then cut the field to cause subcooled water in the cells to flash freeze. The mag field wiggles the water to keep it from forming ice crystals, so when it stops, all the water tries to freeze at once. I think it was called CAS and done by ABI-net, who sell it for tissue preservation as well as bulk food freezing (for improved flavor).

    Reply
  10. I imagined it wouldn’t be so easy as just scaling it, given they use infrared radiation and the human body is a poor transmission medium at such wavelengths (it is not completely opaque to it, though).

    My hunch is that the technologies and observations made on these smaller examples of cryopreservation will serve for lateral or parallel developments later, probably using microwaves or other methods for uniformly giving the energy and for protecting the cells.

    We usually require some working example to start with, for taking things from there.

    But I admit that things can stop there for a while, there is no warranty at all that things that work at the micro and mesoscale work at the macroscale.

    Reply
  11. I recall years ago we were doing calculations on ultra-fast heating of cryopreserved tissues using nano-sized thermite bombs… (Just blue sky stuff on a cryonics forum.) and potentially you could reach heating rates so high that the real limit was your skin spalling off due to the rate of thermal expansion causing a shock wave to propagate through the tissue. So I’m not surprised at these results.

    But this particular research won’t scale to human body size, due to the need to supply the energy from outside.

    Reply
  12. One small zebra fish embryo sized step towards cryostasis for larger animals. And a big step towards taking all kinds of egg laying/small larva-having animals to Mars or anywhere.

    Once we can do it for rodents and such, we will know humans aren’t far away, albeit the obstacles will still be considerable, given this involves surface vs volume effects.

    But once it exists, we could sleep (or rather reversibly die) our way to the stars.

    Reply

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