Designer protein delivery: From natural to engineered affinity-controlled release systems

Temporarily caught in a bind When an atom or molecular fragment is covalently bonded, its release is controlled by the rate of degradation of the bond or by the rate of degradation of the matrix or shell material that keeps it trapped. When molecules are held by noncovalent interactions, the affinity of the molecule to its binding site can be tuned by a number of parameters, such as changing pH, temperature, or salt concentration. This makes it possible to finely tune the release profile. Pakulska et al. review our increased understanding of these interactions as found in nature, and their increased use for the delivery of molecular agents and therapeutics. Science , this issue p. 10.1126/science.aac4750