Trifluoracetic acid tfa

All reagents, standards, and solvents were used as analytical grade. Caffeic acid (≥98%, HPLC) was purchased from Sigma-Aldrich Chemie GmBh (Steinheim, Germany). d(+)-glucose monohydrate, starch, hypromellose, poloxamer 407 (Kolliphor P 407), β-cyclodextrin, and PROSOLV SMCCTM 50 were obtained from Sigma-Aldrich GmbH (Buchs, Switzerland) and (Penwest, UK), respectively, and all were used as excipients. Ethanol (96%) was purchased from AB “Vilniaus degtine” (Vilnius, Lithuania). Phosphate-buffered saline (PBS) (pH~7.4) was obtained from Gibco (Paisley, UK). Ultrapure water was produced using a water purification system Milli-Q^® (Millipore, Arlington, MA, USA). Chromatographic grade acetonitrile and trifluoracetic acid (TFA) were obtained from Sigma-Aldrich Chemie GmbH (Steinheim, Germany).

Synthetic peptides GakA, GakB, and GakC, which constitute the bacteriocin GarKS, were synthesized by Pepmic Co., Ltd., Suzhou, Jiangsu, China, with >95% purity. The peptides were solubilized in 0.1% (vol/vol) trifluoracetic acid (TFA; Sigma-Aldrich).

Veroclear and SUP706 were purchased from Stratasys (Rehovot) as 3D‐printing and supporting materials, respectively. The stainless‐steel springs were purchased from Tohatsu. Polyurethane films, 100 μm in thickness, and Teflon molds, were obtained from CY International and 3DMD, respectively. Rubber piston stoppers were obtained by disassembly from a 0.3 ml BD ultra‐fine insulin syringe. Medical epoxy (Epo‐tek 301) was purchased from Epoxy Technology. Phosphate‐buffered saline (PBS) and formalin were obtained from Thermo Fisher Scientific. The check valves were purchased from Minivalve. Trifluoracetic acid (TFA) was purchased from Sigma‐Aldrich. Exenatide (MW = 4187 Da) was purchased from Cosmogenetech. Both insulin and glucagon were obtained from NovoNordisk.

Ammonium Bicarbonate (NH₄HCO₃, 99.5%), trypsin (proteomics grade), α-cyano-4-hydroxy-transcynnamic acid (α-CHCA, 99,0%), water (HPLC grade), trifluoracetic acid (TFA, 99,0%), methanol (HPLC grade), acetone, protease inhibitor cocktail and protein standards for protein molecular weight marker were purchased from Fluka-Sigma Aldrich S.r.l. (Milan, Italy). Protein standards and reagent for protein quantification were acquired by Bio-Rad's Laboratories, Inc. (Monza, Italy). iTRAQ reagents and buffers were obtained from Applied Biosystems (Foster City, CA). Peptide and protein standards, for mass spectrometer external calibration, were prepared from the Sequazime peptide mass standard kit (Applied Biosystems, Framingham, MA, USA).

Nanoemulsion concentrate was prepared as follows: 50% of sodium surfactin powder, 30% of 2-(2 ethoxyethoxy) ethanol (trade name Transcutol HP; Gattefossé SAS, Saint-Priest, France) and 20% of ascorbyl tetraisopalmitate (trade name Nikkol VC-IP, Nicco Chemicals Co. Ltd., Tokio, Japan) were subjected to ultrasound for 20 min, at 50 °C, as previously described [7 (link)]. Concentrates were organoleptically inspected for the absence of any thickenings. In case there were none, the obtained pre-concentrate was diluted in a glass beaker, 50 mg to 10 mL of water at temperature 37 °C, and further stirred on a magnetic stirring plate.
surfactin was obtained from microbial fermentation with B. subtilis natto KB1, as described before [7 (link),43 (link)]. All medium components were purchased from BioShop LabEmpire (Rzeszow, Poland). All solvents for chromatographic separations were of HPLC and/or MS grade for HPLC and MS analyses, respectively. Trifluoracetic acid (TFA) and surfactin standards were purchased from Sigma Aldrich.

Acetonitrile (HiPerSolv Chromanorm of LC–MS grade) was purchased from VWR Chemicals (Radnor, USA). Petroleum ether (per analysis; 40–65%) was purchased from PENTA chemicals (Prague, Czech Republic). Trifluoracetic acid (TFA) and standards of linolenic and linoleic acids were purchased from Sigma‐Aldrich (Prague, Czech Republic).