Particularly, inter-chain interactions in polymer (I) occur by means of hydrogen bonds between titanium hydroxyl groups and ethereal oxygens of PEG chains, while polymer (II) contains both titanium PEG interactions and a second type of inter-chain interaction due to the presence of hydrogen bonding clusters around Cl− ions.
The structural analyses show that 1 and 2 possess different structural features despite the same raw materials, which are 1D chain structure featuring 6-member-water H-bonds cluster and 3D bbi-pillared wavy-like layer framework, respectively.
We have recently shown that soft matrices can greatly increase the death rate in a bond cluster by inducing severe stress concentration near the adhesion edges.
In the present paper, we report a more striking effect that, irrespective of stress concentration, soft matrices also suppress the birth rate in a bond cluster by increasing the local separation distance between open bonds.
The fact that biological tissues are stable over prolonged periods of time while individual receptor-ligand bonds only have limited lifetime underscores the critical importance of cooperative behaviors of multiple molecular bonds, in particular the competition between the rate of rupture of closed bonds (death rate) and the rate of rebinding of open bonds (birth rate) in a bond cluster.
Therefore, adhesion size can play a very important role in the stability of a bond cluster: small clusters can easily switch between adhesion and deadhesion, as in short-lived focal complexes, while large clusters tend to have a much longer lifetime similar to stable focal adhesions.
Second, we have shown in this paper a more striking result that low stiffness of cell/matrix tends to increase local surface separation at open bonds and make them difficult to rebind, effectively killing the birth rate in a bond cluster.
Under certain conditions, weakly bonded clusters of molecules (such as an argon atom in association with a hydrogen chloride molecule) can exist; such delicately bonded species are called van der Waals molecules.
Two hydrogen-bond clusters between two dimers are important to stabilize the tetramer.
The hydrogen-bond clusters (shown as stick models) flank the two sides of this region.
