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Page 4 of 26 Yang et al. Soft Sci 2024;4:9 https://dx.doi.org/10.20517/ss.2023.43

LMs feature inherently high thermal conductivity and flexibility simultaneously. They have been widely
exploited as effective thermal interface materials (TIMs) to enhance interfacial heat transfer [31-33] . Through
simple manipulations under room temperature and ambient pressure, LMs can be prepared into multiform
[34]
combinational materials, including micro-/nano-scale LM particles with various morphologies . Recently,
it has also been proven that LMs are excellent metal solvents for nanoengineering or for producing various
morphological metals [35,36] . The transformability of LM micro-/nano-particles (LMMPs/LMNPs) enables
them to be applied in multiple fields, including printed electronics, drug delivery, biological sensing, etc.
Moreover, resembling noble metal nanoparticles, LMNPs are also capable of displaying localized surface
plasmon resonance (LSPR) , endowing them with high-efficiency PT conversion capability. As verified by
[37]
a few works, LMNPs showed a considerable PT effect , consequently facilitating efficient elimination of
[38]
cancer cells and inhibiting the regrowth of tumors [39-43] . Except for transforming into nanoparticles
independently, LMs could also accommodate a wide range of micro-/nano-particles to form LM composites
with modifications of specific characteristics . In this perspective, the basic properties of LMs will be
[44]
briefly introduced; interfacial issues are involved in almost all the manipulation of LMs, and they will be
emphatically discussed. Then, based on these impressive properties and phenomena of LMs, their recent
advanced applications in cryobiology will be presented [Figure 1]; lastly, from the perspective of future
development of LMs in cryobiology, possible future application scope will be proposed.

LM-BASED FUNCTIONAL MATERIALS
Preparation of micro-/nano-LM
The liquid nature of LMs enables them to be easily prepared into various modalities. Compared to rigid
metallic nanoparticles, which are practically synthesized by reductive methods, LMs could be scaled down
through a facile top-down strategy. To obtain LMMPs or LMNPs, the probe-sonication method is usually
applied. Generally, bulk LMs are placed in a dispersant solution (e.g., deionized water, ethyl alcohol), and
then, the ultrasonic probe induces cavitation to smash LMs into smaller particles with oxide skin covered.
During the sonication process, small particles still have the possibility to collide with each other and
coalesce together to form larger particles. Several factors, such as activation power, sonication time, and
temperature, can influence the sonication efficiency and the size of particles. At the beginning of sonication,
the mean diameter decreases as time extends, and some large bulks remain unbroken in this state. As
sonication keeps acting, the mean diameter becomes smaller till a minimum value. The mean size of
LMNPs is highly correlated to the LM type, solvent properties, temperature, mass ratio, etc. The sonication
power has no impact on the eventual size of LMNPs but only affects the time spent in reaching the eventual
state [45,46] . High temperature tends to result in a larger particle size, which is probably attributed to the
decrease of the cavitation effect, reducing the break-up ability of sonication . In practice, for the purpose
[46]
of acquiring relatively uniform and small LMNPs, static or centrifugal precipitation of large particles is
always essential [47,48] [Figure 2A].

LMs incorporated with other micro-/nano-particles
Despite the inherent merits of LMs, researchers still sought to further improve their performance in
multiple aspects. Fortunately, the liquid nature provides LMs a universal platform to combine with diverse
materials through simple mechanical agitation methods. Chang et al. revealed the underlying mechanism of
this process. While agitating the mixture of LM and nanoparticles, air-induced gallium oxide skin is
continuously cracked into pieces, and new oxides occur synchronously. Nanoparticles can hardly enter the
LM because of the intrinsic high surface tension. Nevertheless, they become ensconced in adhesive oxide
[49]
debris while being agitated, enabling easy internalization of the nanoparticles by LM . As a result, LMs
successfully integrated diverse functional nanoparticles [Figure 2B].