Photoinduced Fusion of Micro‐Vesicles Self‐Assembled from Azobenzene‐Containing Amphiphilic Diblock Copolymers

Abstract

Poly(N‐isopropylacrylamide)‐block‐poly{6‐[4‐(4‐methylphenyl‐azo) phenoxy] hexylacrylate} (PNIPAM‐b‐PAzoM) was synthesized by successive reversible addition‐fragmentation chain transfer (RAFT) polymerization. In H2O/THF mixture, amphiphilic PNIPAM‐b‐PAzoM self‐assembles into giant micro‐vesicles. Upon irradiation of light at 365 nm, fusion of the vesicles was observed directly under an optical microscope. The real‐time fusion process is presented and the derivation is preliminarily due to the perturbation by the photoinduced trans‐to‐cis isomerization of azobenzene units in the vesicles.magnified image

Light‐Responsive Block Copolymers

“…For instance, 1-pyrenemethanol (hydrophobic dye) can Reproduced with permission from ref. [31] be retained in the hydrophobic core at pH ¼ 10, while in acidic condition (pH ¼ 3) the polar hydrated core released the dye.…”

“…[31,34] Fusion of giant micro-vesicles selfassembled from poly(N-isopropylacrylamide)-block-poly(acrylate) bearing azobenzene chromophores as side-groups (PNIPAM-b-PAz) was investigated by Zhang and coworkers. [31] The vesicles presented in Figure 8 (V3, V4, V5) were self-assembled in THF/water (50:50 vol.-%) and showed diameters between 4 and 5 mm. The fusion occurred as soon as they were exposed to UV light and was followed by optical microscopy.…”

“…[29][30][31][32][33][34][35][36][37][38] Especially interesting is the fusion process of giant block copolymer vesicles triggered by photo-irradiation, which mimics some biological processes. [31,34] Fusion of giant micro-vesicles selfassembled from poly(N-isopropylacrylamide)-block-poly(acrylate) bearing azobenzene chromophores as side-groups (PNIPAM-b-PAz) was investigated by Zhang and coworkers. [31] The vesicles presented in Figure 8 (V3, V4, V5) were self-assembled in THF/water (50:50 vol.-%) and showed diameters between 4 and 5 mm.…”

Phase-separation and photoresponse in binary azobenzene-containing polymer vesicles

“…Specially, azobenzene-containing polymersomes, which show reversible cis-trans photoisomerization of azobenzene groups under irradiation with light at different wavelengths, are also potential candidates for photo-controlled drug release [5,6]. Such photoresponsive properties of azobenzene-containing vesicles are related with the variation of size, fusion, bursting and reversible aggregation [7][8][9][10].…”

Synthesis and Self-assembly Behavior of a Thermo-/photo-dual Responsive Triblock Copolymer

“…偶氮苯 基团是一种广泛研究的光响应性基团, 在紫外光与可见 光的交替作用下, 会发生可逆的光诱导顺反异构化反 应 [12] . 反式(trans)与顺式(cis)构象的偶氮苯在分子极性 上有较大差异, 进而在宏观上能引起两亲性嵌段共聚物 DOI: 10.6023/A13010117 胶束的光致解离和再组装 [13] 、囊泡的光诱导融合 [14] 、胶 体球的光致解聚、 分散和溶解等行为 [15～16] . 聚 N-异丙基 丙烯酰胺(PNIPAM)是典型的温敏性聚合物, 具有一个 低临界相变温度(LCST), 通常为 32 ℃ [17] .…”