Modulating light‐tunable acid sensitivity of a bioinspired polymer simply by adjusting the position of a single methoxy substituent

Abstract

This article describes a rhodopsin-inspired photosensitive polymer whose light-tunable acid sensitivity can be widely modulated simply by adjusting the position of a single methoxy substituent in the aromatic rings of cinnamyl groups. The welldefined poly(5-ethyl-5-methacryloyloxymethyl-2-(p-methoxystyryl)-[1,3]dioxane) (PEMpMSD) and poly(5-ethyl-5-methacryloyloxymethyl-2-(o-methoxystyryl)-[1,3]dioxane) (PEMoMSD) as well as poly(5-ethyl-5-methacryloyloxymethyl-2-styryl-[1,3]dioxane) were synthesized via reversible addition-fragmentation chain transfer (RAFT) process. The results demonstrated that the para-methoxy substitution of EMpMSD monomer led to the more shortened initialization period and rapid chain propagation of RAFT process than 5-ethyl-5-methacryloyloxymethyl-2-styryl-[1,3]dioxane monomer under mild visible light radiation at 25 C. The ortho-methoxy substitution of PEMoMSD led to high degree of photoinduced Z-isomerization over 80%. Moreover, the para-methoxy substitution of PEMpMSD led to the rapid hydrolysis of the cyclic acetal linkages in ambient acid media, while the ortho-methoxy substitution of PEMoMSD slowed down this hydrolysis. This hydrolysis slowed down on Z-isomerization particularly in PEMoMSD. These effects widely broadened the tunability of the light-modulated acid sensitivity. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 495-508, 2012 KEYWORDS: biomimetic; reversible addition fragmentation chain transfer (RAFT); stimuli-sensitive polymers; structureproperty relations Additional Supporting Information may be found in the online version of this article.

Modulating structural stability and acid sensitivity of photosensitive polymer micelles simply via one‐batch UV irradiation

“…Irradiating their acetone solutions with UV light led to Z ‐isomerization of cinnamyl groups, thus remarkably improving the acid stability of their neighboring cyclic acetal linkages. Moreover, introducing a methoxy substituent to the para or ortho position in aromatic rings of cinnamyl groups could widely tune the reactivity of their photoisomerization, thus modulating the acid sensitivity of their neighboring cyclic acetal linkages 39. However, the photodimerization reaction of cinnamyl groups that was commonly observed in UV irradiation of cinnamic ester or cinnamate groups27–29, 40, 41 was not observed in this case.…”

Review on Photo-Responsive Polymeric Interfaces in Biomedical Applications

“…The majority of light-responsive chemical moieties are responsive in the UV spectral range and this property is useful for in vitro applications. [15,[30][31][32][33] Possible applications of photo responsive polymers include reversible optical storage, polymer viscosity control, photomechanical transduction and actuation, bioactivity switching of proteins, tissue engineering, and drug delivery [15,16]. Several light-sensitive particles have been encapsulated within vesicles that cause a physical change upon light exposure, leading to vesicle disruption.…”

“…Irreversible photswichers can involve changes in the molecular shape by external stimuli, ex-diarylethenes, thiophenefulgides [6]. Reversible photo switches can involve dimerization reactions such as those between pairs of cinnamates [7,8] or coumarins [9]. However these tend to be triggered by UV light, which may be damaging biological tissues.…”

Photo‐control of biological systems with azobenzene polymers

“…Reversible photoswitches can involve dimerization reactions such as those between pairs of cinnamates or coumarins, however these tend to be triggered by UV light which may be damaging to tissues. Employing a reversible ring opening and closing reaction, spiropyrans have made an appearance in the literature lately, acting as surface switches for actuating and detecting in a biological setting .…”