Single UV or Near IR Triggering Event Leads to Polymer Degradation into Small Molecules

Abstract

We report two polymers with UV- and NIR-removable end caps that respond to a single light activated event by complete cleavage of the polymer backbone via a self-immolative mechanism. Two photocleavable protecting groups were used to cap the polymers; o-nitrobenzyl alcohol (ONB) and bromo-coumarin (Bhc). GPC and 1H NMR confirmed complete degradation of the ONB-containing polymer in response to UV. The polymers were formulated into nanoparticles; fluorescence measurements of encapsulated Nile red confirmed release upon photolysis of the endcaps. Contrary to previous work using a similar backbone structure that degrades upon hydrolysis, here, the disassembly process and burst release of the payload are only activated on demand, illustrating the powerful capacity of light to trigger release from polymeric nanoparticles. Our design allows the signal to be amplified in a domino effect to fully degrade the polymer into small molecules. Thus, polymers and nanoparticles can reach maximal degradation without having to use intense and/or long periods of irradiation.

Degradable Controlled-Release Polymers and Polymeric Nanoparticles: Mechanisms of Controlling Drug Release

“…437 Both terminal groups responded to UV radiation (through a one-photon process) and NIR (through a two-photon process), where the backbone consisted of a quinone-methide structure. This backbone is unique, as once the end group is cleaved by incoming radiation, it degrades into its monomers in a domino-like fashion.…”

Optical properties of amphiphilic copolymer-based self-assemblies

“…The subsequent quinonemethide rearrangement of the phenol results in the cleavage of the polymer backbone. This novel strategy allows the light signal to be amplified in a domino effect to fully degrade the polymer into small molecules [34,35]. In addition, the cascade degradation action can also be achieved on both dendrimers and linear polymers terminated with a single phototrigger [35,36].…”

“…This novel strategy allows the light signal to be amplified in a domino effect to fully degrade the polymer into small molecules [34,35]. In addition, the cascade degradation action can also be achieved on both dendrimers and linear polymers terminated with a single phototrigger [35,36]. Taking advantage of the high sensitivity to both UV and NIR light, self-assemblies of selfimmolative polymers are promising in constructing sensors and drug delivery systems [37].…”

Stimuli-Responsive Core–Shell Microcapsules with Tunable Rates of Release by Using a Depolymerizable Poly(phthalaldehyde) Membrane

“…Despite these favorable attributes, however, only one example of a stimuli-responsive core−shell polymeric microcapsule made from a head-to-tail depolymerizable polymer has been demonstrated to date, 10 with additional related examples demonstrated in responsive nanocapsules and micelles. 11,12 Further development of this depolymerizable shell wall concept has been hindered by the limited number of polymers that are capable of depolymerizing from head-to-tail in response to a specific signal, as well as by substantial challenges in fabricating core−shell microcapsules using polymers that are primed to depolymerize.In this article, we describe the use of flow-focusing microfluidic strategies for fabricating these types of depolymerizable core−shell microcapsules. 13−15 This technique is highly reproducible, readily forms capsules that contain aqueous interiors, is capable of generating capsules that can be suspended in an aqueous solution that differs from the solution within the capsule, and does not require synthetic manipulation of the polymer for incorporation into the shell wall.…”