Small molecules, release

Larsen MB, Boydston AJ (2014) Successive mechanochemical activation and small molecule release in an elastomeric material. J Am Chem Soc 136 1276... 

Schematics of the basic types of polymerization reactions. A. Condensation polymerizations, showing both A2/B2 and AB systems. "The small molecule released (often water) is not shown. B. Addition jxrlymerization. C. Ring-opening polymerizations, showing both a path that has some relationship to condensation polymers and one that is driven by ring strain and looks more like an addition polymerization.

The chemistry together with all chemicals involved and new chemical bonds formed, should be able to sustain the processing enviroiunents (high temperature, high shear, the presence of oxygen, moisture and other species that may be harmful to the chemistry). Also, chemicals rtsed and small molecules released by the reaction should meet certain health and safety regulations. 

Nisin acts bactericidally primarily against gram-positive bacteria. It acts best at acid pH and is almost insoluble at physiological pH. Nisin and probably all lantibiotics appear to permeabilize the bacterial ceU membrane to release small molecules, resulting in an immediate coUapse of the membrane... 

Although current matrix diffusional systems are most suitable for small-molecule compounds, it has been demonstrated (84) that soHd hydrophobic polymers allow dispersed powdered macromolecules of nearly any size, for example, ethylene—vinyl acetate copolymers containing dispersed polypeptides, to be released for periods exceeding 100 days. 

Condensation polymerization can occur hy reacting either two similar or two different monomers to form a long polymer. This reaction usually releases a small molecule like water, as in the case of the esterifrcation of a diol and a diacid. In condensation polymerization where ring opening occurs, no small molecule is released (see Condensation Polymerization later in this chapter). 

Synaptic vesicles mediate the release of small molecules other than classical neurotransmitters and neuropeptides. Of these, zinc and ATP are the best characterized. NMDA and GABA receptors contain binding sites for zinc, and zinc exerts a direct effect on... 

Allcock HR, Shawn R, and Scopelianos AG. Poly [(amino acid ester) phosphazenes] as substrates for the controlled release of small molecules. Biomaterials, 1994, 1, 5563-5569. 

---