Elsevier Acta Medica Okayama 0927-7757 520 2017 Indocyanine green-laden poly(ethylene glycol)-block-polylactide (PEG-b-PLA) nanocapsules incorporating reverse micelles: Effects of PEG-b-PLA composition on the nanocapsule diameter and encapsulation efficiency 764 770 EN Takaichi Watanabe Department of Applied Chemistry and Biotechnology, Graduate School of Natural Science and Technology, Okayama University Yui Sakamoto Department of Applied Chemistry and Biotechnology, Graduate School of Natural Science and Technology, Okayama University Tetsuya Inooka Division of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama University Yukitaka Kimura Division of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama University Tsutomu Ono Department of Applied Chemistry and Biotechnology, Graduate School of Natural Science and Technology, Okayama University Reverse micelles are thermodynamically stable systems, with a capacity to encapsulate hydrophilic molecules in their nanosized core, which is smaller than the core generally obtained with water-in-oil-emulsion droplets. Herein, we present a simple technique for the preparation of poly(ethylene glycol)-block-polylactide (PEG-b-PLA) nanocapsules encapsulating a hydrophilic photosensitizer (indocyanine green, ICG), which exploits reverse micelle formation and subsequent emulsion-solvent diffusion. We establish the effect of the PEG-b-PLA composition and the co-surfactant volume on the diameter and water content of the reverse micelles. We demonstrate that the composition of PEG-b-PLA affects also the diameter and encapsulation efficiency of the resulting nanocapsules. We show that the ICG-laden nanocapsules fabricated under the most optimal conditions have a diameter of approximately 100 nm and an ICG encapsulation efficiency of 58%. We believe that the method proposed here is a promising step towards the preparation of hydrophilic drug-laden polymer nanocapsules with a small diameter and therefore suitable for use in drug delivery applications based on enhanced permeability and retention (EPR) effect-driven passive targeting. No potential conflict of interest relevant to this article was reported.