Thanks Guy!

Dear Guy,

That is a very good point that you raise, and somehow in
line with Steven's previous comment.

My view in this issue is that weak bonds are a requirement
for self-assembly, so at the minimum, they are a necessary "burden" that
biological systems have to endure. However, they also provide some direct
advantages over materials based on strong, covalent bonds.

Traditional engineered materials (e.g. metals, ceramics,
etc.) based on covalent interactions, are usually not suited for many
applications where multifunctionality or controlled reversible transformations
upon stimulation are required.

It is for these applications that weak interactions may
offer some advantages. For example, while collaborative clusters of weak bonds
can still display high strength, the energetic cost to reform a weak bond is
almost negligible compared to the cost of establishing a new covalent bond.
This makes weak bonds especially appealing for self-healing materials.

Biological materials are always in need of multifunctionality
and reorganization capabilities, so in this context, weak interactions usually
outperform covalent bonds. When nature is in need of higher strength, it
usually recurs to clever strategies such as composites and hierarchical architectures
to improve the mechanical performance while retaining the multifunctionality,
rather than stronger bonds.

Thanks,

Luis