The physics & chemistry of directional freezing

Invitation to the Guest Lecture of Prof. Francisco Fernandes

Chemistry of Condensed Matter Lab, Sorbonne University, France

When: Monday, October 27th, 2025; 11-12 h

Where: Technohal TL1133.

Hosts: Julieta Paez (DBE, S&T Faculty) and Séverine Le Gac (AMBER, EEMCS).

The physics & chemistry of directional freezing: implications in biofabrication & cryobiology

Freezing is ubiquitous in nature. In oceans, rivers, soils, and in the atmosphere, ice is formed under radically different environmental conditions that depend on hydration, temperature and pressure. In most of these conditions freezing threatens the integrity and the viability of biological entities. Paradoxically, cryopreservation (i.e. freezing biological entities under strictly controlled conditions) is the only solution to extend the lifespan of living cells, and to preserve biomolecules. In this lecture, I will focus on the interactionbetween biological matter (from biopolymers up to living mammalian cells) with a controlled freezing front¹.

During freezing, ice growth induces a phase separation between pure ice crystals, and the remaining solutes and suspended particles. This strategy can serve as a driving force to design biomimetic systems such as vascular tissue grafts^2,3, muscle tendon junctions⁴ as well as 3D cell culture systems⁵. Our recent results in designing biomaterials from the main components of the Extracellular Matrix such as type I collagen using ice will be addressed in the first part of the lecture. The second part will be devoted to the role of directional freezing as an alternative approach to cryopreservation of cells, from model organisms like yeast and bacteria⁶ to cells relevant in human cell therapy⁷ in absence of toxic components such as DMSO. Overall, we demonstrate the potential of controlled freezing processes to outperform current cryopreservation methods and tackle tissue engineering challenges.

References:

1. Qin et al. J. Mater. Chem. B 2021 9, 889–907.
2. Martinier et al. Chem Soc Rev 2025, 54, 790-82.
3. Martinier et al. Biomater. Sci., 2024, 12, 3124-3140.
4. Rieu et al. ACS Appl Mat & Interf ., 2019 11, 14672-14683.
5. Parisi et al. Biomater. Sci. 2022, 10, 6939–6950.
6. Qin et al. J. Phys. Chem. Lett. 2020 11, 7730–7738.
7. Mathieu et al. in preparation.

Francisco M. Fernandes is an Associate Professor at Sorbonne Université, where he leads the Materials & Biology team at the Condensed Matter Chemistry Laboratory of Paris (LCMCP). Francisco holds a degree in Chemistry and an MSc in Environmental Sciences from the University of Minho in Braga, Portugal. He pursued his PhD under the guidance of Prof. Ruiz-Hitzky at the Materials Science Institute of Madrid, Spain, where he studied bionanocomposite materials. In 2011, he joined the LCMCP in Paris as a postdoctoral fellow, working on collagen-based materials for biomedical applications. Since his appointment in 2013, he has developed a highly original research line that focuses on integrating biological functions into exogenous materials. His work adapts materials science processing techniques to meet the requirements of living matter. His main tool is ice!