Angle-Resolved Linear Dichroism to Probe the Organization of Highly Ordered Collagen Biomaterials.

Controlling the assembly of high-order structures is central to soft-matter and biomaterial engineering. Angle-resolved linear dichroism can probe the ordering of chiral collagen molecules in the dense state. Collagen triple helices were aligned by solvent evaporation. Their ordering gives a strong linear dichroism (LD) that changes sign and intensity with varying sample orientations with respect to the beam linear polarization. Being complementary to circular dichroism, which probes the structure of chiral (bio)molecules, LD can shift from the molecular to the supramolecular scale and from the investigation of the conformation to interactions. Supported by multiphoton microscopy and X-ray scattering, we show that LD provides a straightforward route to probe collagen alignment, determine the packing density, and monitor denaturation. This approach could be adapted to any assembly of chiral (bio)macromolecules, with key advantages in detecting large-scale assemblies with high specificity to aligned and chiral molecules and improved sensitivity compared to conventional techniques.

Magnetic Field Alignment, a Perspective in the Engineering of Collagen-Silica Composite Biomaterials.

Major progress in the field of regenerative medicine is expected from the design of artificial scaffolds that mimic both the structural and functional properties of the ECM. The bionanocomposites approach is particularly well fitted to meet this challenge as it can combine ECM-based matrices and colloidal carriers of biological cues that regulate cell behavior. Here we have prepared bionanocomposites under high magnetic field from tilapia fish scale collagen and multifunctional silica nanoparticles (SiNPs). We show that scaffolding cues (collagen), multiple display of signaling peptides (SiNPs) and control over the global structuration (magnetic field) can be combined into a unique bionanocomposite for the engineering of biomaterials with improved cell performances.

Erratum: Debons et al. Magnetic Field Alignment, a Perspective in the Engineering of Collagen-Silica Composite Biomaterials. Biomolecules 2021, 11, 749.

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Native Collagen: Electrospinning of Pure, Cross-Linker-Free, Self-Supported Membrane.

Rebuilding biological environments is crucial when facing the challenges of fundamental and biomedical research. Thus, preserving the native state of biomolecules is essential. We use electrospinning (ES), which is an extremely promising method for the preparation of fibrillar membranes to mimic the ECM of native tissues. Here, we report for the first time (1) the ES of pure and native collagen into a self-supported membrane in absence of cross-linker and polymer support, (2) the preservation of the membrane integrity in hydrated media in absence of cross-linker, and (3) the preservation of the native molecular structure and recovery of the hierarchical assembly of collagen. We use a multiscale approach to characterize collagen native structure at the molecular level using circular dichroism, and to investigate collagen hierarchical organization within the self-supported membrane using a combination of multiphoton and electron microscopies. Finally, we show that the membranes are perfectly suited for cell adhesion and spreading, making them very promising candidates for the development of biomaterials and finding applications in biomedical research.

Differentiation of neural-type cells on multi-scale ordered collagen-silica bionanocomposites.

Cells respond to biophysical and biochemical signals. We developed a composite filament from collagen and silica particles modified to interact with collagen and/or present a laminin epitope (IKVAV) crucial for cell-matrix adhesion and signal transduction. This combines scaffolding and signaling and shows that local tuning of collagen organization enhances cell differentiation.

Programmed Self-Assembly of a Biochemical and Magnetic Scaffold to Trigger and Manipulate Microtubule Structures.

Artificial bio-based scaffolds offer broad applications in bioinspired chemistry, nanomedicine, and material science. One current challenge is to understand how the programmed self-assembly of biomolecules at the nanometre level can dictate the emergence of new functional properties at the mesoscopic scale. Here we report a general approach to design genetically encoded protein-based scaffolds with modular biochemical and magnetic functions. By combining chemically induced dimerization strategies and biomineralisation, we engineered ferritin nanocages to nucleate and manipulate microtubule structures upon magnetic actuation. Triggering the self-assembly of engineered ferritins into micrometric scaffolds mimics the function of centrosomes, the microtubule organizing centres of cells, and provides unique magnetic and self-organizing properties. We anticipate that our approach could be transposed to control various biological processes and extend to broader applications in biotechnology or material chemistry.