Researchers widely use freeze-drying to preserve biomaterials, including biological nanoparticles such as exosomes, liposomes, and protein nanoparticles. However, this process can induce alterations that compromise their functionality. In this article, we will explore how freeze-drying affects the functionality of biological nanoparticles, the critical factors to consider and strategies to minimise possible damage.
Impact on the functionality of biological nanoparticles
The freeze-drying process involves three main stages: freezing, primary sublimation, ice is removed under high vacuum conditions, and in secondary sublimation residual water molecules are removed.
Functional alterations
Changes induced by freeze-drying can compromise the functionality of biological nanoparticles in several ways:
-Decreased colloidal stability. Recontration in aqueous media can result in non-homogeneous redistribution of particles, generating instability in suspension and affecting their bioavailability.
-Reduced cellular uptake. In exosomes and liposomes, alteration of their surface after freeze-drying may decrease their ability to interact with recipient cells, reducing their biological effectiveness.
-Changes in controlled drug release. If nanoparticles are used as drug delivery systems, their release profile may be altered after freeze-drying, affecting the dosage and time to action of the compound.
–Loss of biological activity. In nanoparticles carrying proteins or enzymes, freeze-drying may cause conformational changes that decrease their functional activity or ability to interact with specific biomarkers.
Strategies to minimize adverse effects
Researchers have developed several strategies to mitigate the negative effects of freeze-drying on the functionality of biological nanoparticles, including:
-Use of cryoprotectants and lyophiloprotectants. Substances such as trehalose, sucrose and mannitol can stabilize the strustures during dehydration, preventing loss of functionality.
-Optimization of the freezing profile. Slow freezing can minimize mechanical stress and avoid the formation of large ice crystals that alter the functionality of the nanoparticles.
-Control of reconstitution conditions. The medium and pH in which researchers rehydrate the nanoparticles can influence their post-lyophilization stability and functionality. This ensures that the nanoparticles regain their original activity.
Conclusion
Lyophilization powerfully preserves biological nanoparticles, but researchers must apply it with caution to avoid altering their functionality. The use of appropriate protectants and precise control of process conditions can improve the stability and viability of these systems. As biomedicine advances with nanotechnology, researchers will continue designing effective preservation strategies as a critical area of study.