Anhydrous triethylamine

Triethoxysilane, 4-nitrophenyl chloroformate (NPC), ethylenediamine, and acryloyl chloride were obtained from TCI Japan. 1-Decene, Pluronic F127, methylene chloride, and anhydrous triethylamine from Sigma-Aldrich (St. Louis, MO, USA). Petroleum ether from Wako Pure Chemical Industries, Tokyo, Japan. No modifications or alterations were made to the chemicals before their use, ensuring reliable and accurate results. To obtain pure and deionized water, a Sartorius arium 611 UV water purification system was employed (Sartorius AG, Goettingen, Germany).

PMD (p-menthane-3,8-diol) was used as received (BOC, New York, NY, United States). D-Squame tapes were obtained from Clinical & Derm (Des Plaines, IL, United States). Parafilm M was obtained from AMCOR (Chino, CA, United States). Acrylic acid (AA) in liquid form (99%, Fisher Scientific, Loughborough, United Kingdom) was passed through the aluminium oxide column to remove the inhibitor prior to use in copolymerization. Azobisisobutyronitrile (AIBN) was used as an initiator, and was recrystallized twice in methanol (Sigma-Aldrich, Gillingham, United Kingdom). Sodium hydroxide (Fisher Scientific, United Kingdom), acryloyl chloride, and anhydrous triethylamine (Sigma-Aldrich, United Kingdom) were used as received. Porcine liver esterases (PLEs), acryloyl chloride, and ammonium acetate were from Sigma-Aldrich (Merck, United Kingdom). Poly(acrylic acid) (weight–average molecular weight (Mw) = 6000 Da) was purchased from Polysciences (Bergstrae, Germany). Acetonitrile, ethanol and all the solvents used were of liquid chromatography–mass spectroscopy (LC–MS) grade and were procured from Fisher Scientific (United Kingdom), and were used without further purification. Thin-layer chromatography (TLC) plates were from Merck (Darmstadt, Germany).

SPB was donated by Osaka Organic Chemical Industry, Ltd (Osaka, Japan) and used without further purification. d-(+)-Trehalose dihydrate was purchased from Nacalai Tesque (Kyoto, Japan). Tin(ii) 2-ethylhexanoate and ε-caprolactone were purchased from Tokyo Chemical Industry Co., Ltd (Tokyo, Japan). 4-Cyano-4-[(dodecylsulfanylthiocarbonyl)-sulfanyl]pentanol (RAFT agent), V-501 initiator (4,4-azobis(4-cyanovaleric acid)), lactate dehydrogenase (from rabbit muscle), anhydrous triethylamine, sodium pyruvate, β-nicotinamide adenine dinucleotide (reduced disodium salt hydrate), and methacrylic anhydride were purchased from Sigma-Aldrich Corp. (St. Louis, MO, USA). Insulin (human) was purchased from Roche Diagnostics GmbH (Mannheim, Germany).