In this study we constructed spherical photo‐responsive microcapsules composed of three photo‐switchable DNA strands. These strands first formed a three‐way junction (TWJ) motif that further self‐assembled to form microspheres through hybridization of the sticky‐end regions of each branch. To serve as the photo‐switch, multiple unmodified azobenzene (Azo) or 2,6‐dimethyl‐4‐(methylthio)azobenzene (SDM‐Azo) were introduced into the sticky‐end regions via a d‐threoninol linker. The DNA capsule structure deformed upon trans‐to‐cis isomerization of Azo or SDM‐Azo induced by specific light irradiation. In addition, photo‐triggered release of encapsulated small molecules from the DNA microcapsule was successfully achieved. Moreover, we demonstrated that photo‐triggered release of doxorubicin caused cytotoxicity to cultured cells. This biocompatible photo‐responsive microcapsule has potential application as a photo‐controlled drug‐release system.

High crystalline and high molecular weight poly[(acetoxyethyl)oxymethylene] was prepared from .S-acetoxypropionaldehyde with use of triethylaluminum and diethylaluminum chloride at low temperature. It was also established by infrared, NMR, and X-ray analyses that even protonic acid such as sulfuric acid could produce the crystalline, isotactic poly[(acetoxyethyl)oxymethylene] at -78°C. It is suggested that the polar acetoxy group participates in the steric control of polymerization and the mechanism is presumed.KEY WORDS .S-Acetoxypropionaldehyde / Stereospecific Polymerization / Crystalline Poly[(acetoxyethyl)oxymethylene] / Polar Substituent / Protonic Acid/ Organoaluminum / As part of the studies on polar-substituted poly-( oxymethylene)s, 1-3 the present paper describes an attempt of polymerizing .S-acetoxypropionaldehyde at low temperature and of characterizing the resulting polymer. It was found that crystalline isotactic poly[(acetoxyethyl)oxymethylene] is produced by organoaluminum and protonic acid. It is noticeable that a protonic acid such as sulfuric acid could produce the crystalline polymer and attention should be drawn to the role of polar substituents in the stereospecific polymerization.

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