Molecular mobility of scaffolds' biopolymers influences cell growth

Mineralization potential of cellulose-nanofibrils reinforced gelatine scaffolds for promoted calcium deposition by mesenchymal stem cells

Cellulose-nanofibrils (CNFs) enriched gelatine (GEL) scaffolds were fabricated in-situ by the combined freeze-thawing process and carbodiimide crosslinking chemistry. The original- and variously surface anionised CNFs (carboxylated/CNF-COOH/, and phosphonated with 3-AminoPropylphosphoric Acid/CNF-COOH-ApA/) were used in order to tune the scaffolds' biomimetic structure towards a more intensive mineralization process. The pore size reduction (from 208±35μm to 91±35μm) after 50% v/v of CNFs addition to GEL was identified, while separated pore-walls' alignment vs. shorter, dense and elongated pores are observed when using 80% v/v of original-CNFs vs. anionised-CNFs, all of them possessed osteoid-like compressive strength (0.025-0.40MPa) and elasticity (0.04-0.15MPa). While randomly distributed Ca²⁺-deficient hydroxyapatite/HAp/(Ca/P≈1.4) aggregates were identified in the case of original-CNF prevalent scaffolds after four weeks of incubation in SBF, the more uniform and intensified deposition with HAp-like (Ca/P≈1.69) structures were established using CNF-COOH-Apa. The growth of Mesenchymal Stem Cells (MSCs) was observed on all CNF-containing scaffolds, resulting in more extensive Ca²⁺ deposition compared to the positive control or pure GEL scaffold. Among them, the scaffold prepared with the 50% v/v CNF-COOH-ApA showed significantly increased mineralization kinetic as well as the capacity for bone-like patterning in bone tissue regeneration.

The effects of macroporosity and stiffness of poly[(methyl vinyl ether)-alt-(maleic acid)] cross-linked egg white simulations of an aged extracellular matrix on the proliferation of ovarian cancer cells

The effects of macroporosity and stiffness of P(MVE-alt-MA) cross-linked EW simulations of an aged ECM on the proliferation of cancer cells.

Cell-scaffold adhesion dynamics measured in first seconds predicts cell growth on days scale – optical tweezers study

Understanding the cell-biomaterial interface from the very first contact is of crucial importance for their successful implementation and function in damaged tissues. However, the lack of bio- and mechano-analytical methods to investigate and probe the initial processes on the interface, especially in 3D, raises the need for applying new experimental techniques. In our study, optical tweezers combined with confocal fluorescence microscopy were optimized to investigate the initial cell-scaffold contact and to investigate its correlation with the material-dependent cell growth. By the optical tweezers-induced cell manipulation accompanied by force detection up to 100 pN and position detection by fluorescence microscopy, accurate adhesion dynamics and strength analysis was implemented, where several attachment sites were formed on the interface in the first few seconds. More importantly, we have shown that dynamics of cell adhesion on scaffold surfaces correlates with cell growth on the days scale, which indicates that the first seconds of the contact could markedly direct further cell response. Such a contact dynamics analysis on 3D scaffold surfaces, applied for the first time, can thus serve to predict scaffold biocompatibility.

Resolving Internal Motional Correlations to Complete the Conformational Entropy Meter

Conformational entropy (SΩ) has long been used to theoretically characterize the dynamics of proteins, DNA, and other polymers. Though recent advances enabled its calculation also from simulations and nuclear magnetic resonance (NMR) relaxation experiments, correlated molecular motion has hitherto greatly hindered both numerical and experimental determination, requiring demanding empirical and computational calibrations. Herein, we show that these motional correlations can be estimated directly from the temperature-dependent SΩ series that reveal effective persistence lengths of the polymers, which we demonstrate by measuring SΩ of amphiphilic molecules in model lipid systems by spin-labeling electron paramagnetic resonance (EPR) spectroscopy. We validate our correlation-corrected SΩ meter against the basic biophysical interactions underlying biomembrane formation and stability, against the changes in enthalpy and diffusion coefficients upon phase transitions, and against the energetics of fatty acid dissociation. As the method can be directly applied to conformational analysis of proteins and other polymers, as well as adapted to NMR or polarized fluorescence techniques, we believe that the approach can greatly enrich the scope of experimentally available statistical thermodynamics, offering new physical insights into the behavior of biomolecules.