We conjugated tetraethylene glycol, a short, neutral amphiphilic, monodisperse polymer with a benzothiazole fluorophore (TEG-BTA-2) to form a switchable self-assembled structure in an aqueous medium for functional applications. TEG-BTA-2 formed a microsphere in an aqueous medium, however, switched to a rice-like microcapsule for curcumin encapsulation. Curcumin-loaded TEG-BTA-2 microcapsules disassembled upon interacting with a protein and exhibited protein affinity-controlled release with an in vitro visualization property.

Abstract

A short monodisperse poly(ethylene glycol) (PEG) and a neutral organic rotamer conjugate TEG-BTA-2 amphiphile was designed for the construction of a stimuli-responsive switchable self-assembled structure for drug encapsulation by noncovalent interaction and targeted controlled delivery. A short PEG, tetraethylene glycol (TEG) was covalently attached with a neutral organic rotamer benzothiazole dye (BTA-2) affording the neutral TEG-BTA-2 (<500 D). The TEG-BTA-2 is self-assembled into a microsphere in an aqueous medium, but remarkably undergoes morphology change switching to a rice-like microcapsule for curcumin encapsulation. Curcumin-loaded microcapsules were stable in an aqueous solution, however, were noticed disintegrating upon the addition of BSA protein. This is possibly due to an interaction with BSA protein leading to a protein affinity-controlled curcumin release in a neutral PBS buffer. Moreover, cell internalization of the neutral amphiphile TEG-BTA-2 into A549 cells was observed by fluorescence microscopy, providing an opportunity for application as a molecular vehicle for targeted drug delivery and monitoring.