Photoresponsive Aqueous Dissolution of Poly(N-Isopropylacrylamide) Functionalized with o-Nitrobenzaldehyde through Phase Transition

Abstract

We report a sharp photoinduced aqueous dissolution of the copolymer through phase transition based on the photochemical reaction of o-nitrobenzaldehyde (NBA) and the principle of polymer effect. We synthesized the copolymers having poly( N-isopropylacrylamide) main chain and NBA side chain at 4, 7, and 10 mol % functionalizations and analyzed their photoresponsive characteristics. Light with 365 nm wavelength converted NBA groups at copolymer side chains to carboxylic acid efficiently at the rate of 7.3 cm/J, and in the case of 10 mol % functionalization, the irradiation dosage no more than 56 mJ/cm induced sharp aqueous dissolution of the copolymer thin layer in pH 7.4 at 25 °C. As example applications, we demonstrated on-demand release of polyethylene beads and fluorescent-labeled albumins, which had been immobilized on a substrate surface via the copolymers, by the precisely controlled light irradiation using a microprojection system. Also, we examined application of the copolymers to the selective recovery of living cells from culture substrate under microscopic observation. As a result, mild light irradiation at room temperature triggered immediate detachment of the cultured adherent cells only in the irradiated areas without critical influence on their viability.

Acylhydrazone-based supramolecular assemblies undergoing a converse sol-to-gel transition on trans → cis photoisomerization

“…In situ sol-to-gel transition generated valves Microuidic technologies have been recently regarded as an advanced tool to investigate non-equilibrium assemblies and controlled reactive processes in self-assembly research. [61][62][63][64] Introducing stimuli-responsive materials as a valve would realize the non-contact microuidic ow control, [65][66][67][68] probably producing simplied and versatile microuidic devices. Nevertheless, most reported valves were based on temperature-and electro-responsive systems, 69,70 which are not easy to achieve ow control in situ and are comparatively complicated.…”

Precision synthesis for well-defined linear and/or architecturally controlled thermoresponsive poly(N-substituted acrylamide)s

“…A complex system in which polymers change their stimuli-responsive properties in response to another stimulus has also been developed. 27,28 The current research on stimuli-responsive polymers has combined polymer chemistry with a range of other disciplines, such as organic and inorganic chemistry, biochemistry, photochemistry, electrochemistry, carbon chemistry, sugar chemistry, hostguest and supramolecular chemistry, material chemistry, surface and interfacial chemistry, and environmental chemistry.…”