Sequencing sheared, preparation

Internal mixers must be ran in a full or nearly full condition, so a batch recipe is calculated to provide an appropriate volume. If not filled, the ingredients will not be properly sheared and heat transfer will be compromised. Typical commercial mixers have a batch size of at least 100 pounds of compound. A mixer of this size will have a drive motor of no less than 75 horsepower. Proper dispersive mixing is a balance between proper shear, sequence of addition of ingredients, and thermal stability. Mixers have extensive monitoring instrumentation that provides continuous feedback about thermal conditions, rotor torque, and rotor speed. Once a mixing process has been developed, a standard protocol is followed for preparation of the compound. 

Coiled coils are interesting as designable cross-linkers because of the well-understood relation between the peptide sequence, the folded and dimerized structure, and the binding affinity. However, as described above, hydrogels based on coiled coils are generally weak, with shear moduli only up to 1 kPa. Furthermore, the use of recombinant protein expression or solid-phase peptide synthesis limits the scale on which these materials can be prepared. However, this approach allows tuning both the cross-Unks as well as the backbone to regulate the mechanical properties and incorporate bioactivity. 

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