Stimuli-Induced Architectural Transition as a Tool for Controlling the Enzymatic Degradability of Polymeric Micelles.

Enzyme-responsive polymeric micelles hold great potential as drug delivery systems due to the overexpression of disease-associated enzymes. To achieve selective and efficient delivery of their therapeutic cargo, micelles need to be highly stable and yet disassemble when encountering their activating enzyme at the target site. However, increased micellar stability is accompanied by a drastic decrease in enzymatic degradability. The need to balance between stability and enzymatic degradation has severely limited the therapeutic applicability of enzyme-responsive nanocarriers. Here, we report a general modular approach for designing stable enzyme-responsive micelles whose enzymatic degradation can be enhanced on demand. The control over their response to the activating enzyme is achieved by stimuli-induced splitting of triblock amphiphiles into two identical diblock amphiphiles, which have the same hydrophilic-lipophilic balance as the parent amphiphile. This architectural transition drastically affects the micelle-unimer equilibrium and therefore increases the sensitivity of the micelles toward enzymatic degradation. As a proof of concept, we designed UV- and reduction-activated splitting mechanisms, demonstrating the ability to use architectural transition as a tool for tuning amphiphile-protein interactions, providing a general solution toward overcoming the stability-degradability barrier for enzyme-responsive nanocarriers.