Titanium nitride nanoparticles for laser nanowarming in cryopreservation

Area of Science:

• Biomaterials science
• Nanotechnology
• Cryobiology

Background:

• Vitrification-based cryopreservation requires rapid rewarming to prevent ice crystal formation and sample damage.
• Laser nanowarming using plasmonic nanoparticles is a promising rewarming technique.
• Gold nanorods (GNRs) are effective but costly and unstable in cryoprotectant solutions.

Purpose of the Study:

• To evaluate titanium nitride nanoparticles (TiN NPs) as a cost-effective and stable alternative to GNRs for laser nanowarming.
• To investigate the effect of surface modification on TiN NP performance in vitrified samples.
• To compare the efficacy of TiN NPs with GNRs for nanowarming *Artemia salina* cysts.

Main Methods:

• Vitrified *Artemia salina* cysts in cryoprotectant droplets were rewarmed using laser irradiation.
• Bare and surface-modified TiN NPs (mPEG-Silane, APTES) were tested at various concentrations and laser pulse durations.
• Nanoparticle stability, toxicity, and effect on cyst hatchability were assessed.
• Performance was compared against a GNR formulation under identical conditions.

Main Results:

• Bare TiN NPs achieved ~85% hatchability at 400 µg mL⁻¹ with a 2 ms laser pulse.
• Surface modification (TiN-mPEG-Silane, TiN-APTES) improved dispersion and reduced optimal concentrations.
• TiN NPs demonstrated stability in cryoprotectant for 14 days and minimal toxicity to *Artemia*.
• TiN formulations required significantly lower concentrations than GNRs for comparable or superior nanowarming outcomes.

Conclusions:

• TiN nanomaterials present a cost-effective, stable, and tunable platform for laser nanowarming.
• Surface modification enhances TiN NP performance and colloidal stability.
• TiN NPs offer a practical and efficient alternative to GNRs for advancing vitrification-based cryopreservation.