Programing Green Light-Responsive Hydrogels: from Photo-Weakening to Photo-unresponsiveness and Photo-Strengthening.

Light-responsive hydrogels are highly valued for their dynamic mechanical properties and biocompatibility. In this study, we present a hydrogel system that can either soften or strengthen on green light exposure, or remain unresponsive to light, depending on the addition of adenosyl cobalamin (AdoCbl) and Co2+. These protein-based hydrogels were formed using genetically encoded SpyTag-SpyCatcher chemistry and included green light-sensitive CarHc protein domains.

Evolution of SARS-CoV-2 spike trimers towards optimized heparan sulfate cross-linking and inter-chain mobility.

The heparan sulfate (HS)-rich extracellular matrix (ECM) serves as an initial interaction site for the homotrimeric spike (S) protein of SARS-CoV-2 to facilitate subsequent docking to angiotensin-converting enzyme 2 (ACE2) receptors and cellular infection. More recent variants, notably Omicron, have evolved by swapping several amino acids to positively charged residues to enhance the interaction of the S-protein trimer with the negatively charged HS. However, these enhanced interactions may reduce Omicron's ability to move through the HS-rich ECM to effectively find ACE2 receptors and infect cells, raising the question of how to mechanistically explain HS-associated viral movement.

Observation of H-H J-couplings in fast magic-angle-spinning solid-state NMR spectroscopy.

While H-H J-couplings are the cornerstone of all spectral assignment methods in solution-state NMR, they are yet to be observed in solids. Here we observe H-H J-couplings in plastic crystals of (1S)-(-)-camphor in solid-state NMR at magic angle spinning (MAS) rates of 100 kHz and above. This is enabled in this special case because the intrinsic coherence lifetimes at fast MAS rates become longer than the inverse of the H-H J couplings.

Analysis of Light-Controlled Artificial Cell-Cell Adhesions.

The precise spatial and temporal regulation of cell-cell adhesions is crucial for understanding the underlying biological processes and for assembling multicellular structures in tissue engineering. Traditional approaches have relied on chemical membrane functionalization and regulated gene expression of native cell adhesion molecules (CAMs), but these methods lack the necessary control and can be detrimental to cells. In contrast, engineered photoswitchable cell-cell adhesions offer a reversible and dynamic regulation at a single-cell resolution.

Adaptive metal ion transport and metalloregulation-driven differentiation in pluripotent synthetic cells.

Pluripotent cells can yield different cell types determined by the specific sequence of differentiation signals that they encounter as the cell activates or deactivates functions and retains memory of previous inputs. Here, we achieved pluripotency in synthetic cells by incorporating three dormant apo-metalloenzymes such that they could differentiate towards distinct fates, depending on the sequence of specific metal ion transport with ionophores. In the first differentiation step, we selectively transported one of three extracellular metal ion cofactors into pluripotent giant unilamellar vesicles (GUVs), which resulted in elevation of intracellular pH, hydrogen peroxide production or GUV lysis.