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Drug Discov Ther. 2019;13(6):343-353. doi: 10.5582/ddt.2019.01090.

Janus microspheres for enhanced enteral drug delivery: Preparation and orientated attachment to a Caco-2 monolayer.

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Laboratory of Pharmaceutics, Faculty of Pharmacy, Osaka Ohtani University, Tondabayashi, Osaka, Japan.
Laboratory of Clinical Pathology, Faculty of Pharmacy, Josai University, Sakadoshi, Saitama, Japan.


Conventional oral preparations generally release incorporated drugs omnidirectionally, including into the lumen, leading to a low bioavailability of drugs that are unstable in the gastrointestinal tract. Here, we designed Janus microspheres for efficient mucosal drug delivery as single-sided-release microspheres with the oriented attachment to mucus and evaluated their attachment to and orientation on a Caco-2 (human Caucasian colon adenocarcinoma cell line) monolayer. The microspheres comprised a mucus-oriented hemisphere of an ammonioalkyl methacrylate copolymer and a protective hemisphere of a hard fat. Fluorescein isothiocyanate-dextran with an average molecular weight of 3,000-5,000 Da (FD4) was used as a model hydrophilic drug. A water-in-oil emulsion-type solvent evaporation method was employed for fabrication of the Janus microspheres. The yield of Janus microspheres was found to be dependent on the polymer-to-hard fat ratio, with a maximum yield of over 90% being obtained at a ratio of 1:2, whereas lower and higher ratios resulted in monolithic or star-shaped microspheres. FD4 was specifically localized in the polymeric hemisphere. A cell culture study revealed that the Janus microspheres attached to a Caco-2 monolayer via their polymeric hemispheres with the hard fat hemisphere providing a protective sealing. This may lead to the development of an effective enteral drug delivery system for biomedicines, such as polypeptides and nucleic acids.


Single-sided-release microspheres; ammonioalkyl methacrylate copolymer; hard-fat; solvent evaporation method

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