Anhydrous calcium chloride

All reagents and solvents were analysis grade, used without further purification. Gold nanostructures synthesis: tetrachloroauric acid, dehydrated tribasic sodium citrate, cetyltrimethyl-ammonium bromide (CTAB), sodium borohydride, ascorbic acid and silver nitrate were purchased from Sigma-Aldrich (St. Louis, MO, USA); hydrochloric acid fuming (Merck, Darmstadt, HE, Germany). mPEG-SH and SH-PEG-COOH (5 kDa, JenKem Technology, Beijing, China). Curcumin nanoemulsions: curcumin (from Curcuma longa, C1386, Sigma-Aldrich), Epikuron 145V (Cargill, Barcelona, Spain), Miglyol 812 (Sasol GmbH, Hamburg, Germany), acetone and ethanol (Merck). Microgels: low viscosity sodium alginate (Sigma-Aldrich), anhydrous calcium chloride (Merck). Milli-Q water used in all the experiments was obtained from the purification of distilled water with a Simplicity SIMS 00001 equipment (Millipore, Molsheim, France). Cell culture: RPMI 1640, DMEM high glucose medium, penicillin and streptomycin (Gibco-BRL, Paisley, UK), fetal bovine serum (FBS, Biological Industries, Cromwell, CT, USA). Viability assays: 3-(4,5-dimetylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H tetrazolium inner salt (MTS) proliferation assay kit (Promega, Madison, WI, USA).

WVP of films was determined gravimetrically at 25 ± 1 °C using a modified ASTM E96-80³¹ procedure. The test film was sealed to a glass dish containing anhydrous calcium chloride (Merck, Darmstadt, Germany), 0% RH, and the dish was placed in a desiccator maintained at 52 ± 2% RH with saturated magnesium nitrate (Merck, Darmstadt, Germany). The water vapor transferred through the film and absorbed by the desiccant was determined by measuring the weight gain. WVP was calculated from the following equation: $$WVP=C\frac{x}{A\mathrm{\Delta }P}$$ where WVP is in g/msPa, x is the film thickness (m), A is area of the exposed film (m²), DP is the water vapor pressure differential across the film (Pa), and C is the slope of the weight gain of the dish, to the nearest 0.0001 g, versus time. Generally, ten weighing were taken over a 7–10 h period. Slopes were calculated by linear regression and correlation coefficient (r²) for all reported data were 0.99 or greater. At least three replicates of each film type were tested for WVP.

Low-viscosity (LV, 250 cPs) and high-viscosity (HV, 20,000–40,000 cPs) sodium alginates (SAs) from brown algae and anhydrous calcium chloride (CaCl₂) were purchased from Sigma Aldrich, Milan, Italy. Deionized water was used for the preparation of the solutions. Sodium alginate (SA) aqueous solutions were prepared at 2% w/v for the HV-SA and 0.5% w/v for the LV-SA solutions. For the fabrication of core/shell microgels, a commercial machine (NF500 MECC, Fukuoka, Japan) was used, equipped with a metal ultra-coaxial needle—inner channel 27 G and outer channel 18 G—and a tailor-made magnetic stirrer working as a collector, as reported in previous studies [31 (link)]. The EFDA parameters were optimized to control the size and shape of microgels. Briefly, the solutions were placed in two different 5 mL syringes, and each one was connected to a syringe pump with an imposed feed rate equal to 0.5 and 2.0 mL/h, respectively. The applied voltage was set at 25 kV, while the tip-to-collector distance was set at 150 mm. Droplets were collected into a CaCl₂ solution at a concentration of 1.1% under magnetic stirring to trigger the ionotropic interaction in the aqueous solution.