Sodium alginate

Initially, 10 g of sodium alginate (Buchi, France) was dissolved in 400 mL of an aqueous 4% (w/v) glucose solution to produce 500 mL of sodium alginate solution at 2%. ASCs from each donor were dispersed in 20 mL of this 2% alginate solution, at 4 × 10⁶ cells/mL. Then, cells were encapsulated by the prilling vibration technique using the B-390 Encapsulator (Buchi, France) fitted with a 150-µm nozzle. The laminar jet of the suspension through the 150-µm nozzle was adjusted to a flowrate of 3.1 mL/min. The vibration frequency, applied to split the laminar jet into fine droplets, was set to 366 Hz. Finally, the voltage of the electrode forming an “umbrella” at the nozzle outlet (to avoid microparticles sticking together) was adjusted to 2000 V. The droplets of sodium alginate containing encapsulated cells then encountered the aqueous jellification solution, containing 76 mM calcium chloride (Calbiochem, France), 85 mM glucose (Macopharma, France), and 6 mM HEPES (Sigma Aldrich, St. Louis, MO, USA) at physiological pH and osmolarity, where the alginate microparticles were formed.
Microparticles were rinsed with lactated Ringer’s solution (Macopharma, France) and stored in ASC culture medium.

The encapsulation of a phage cocktail—S4lw and D5lw—was conducted as previously described with minor modification^{29 (link)}. First, phages S4lw and D5lw at approximately 10⁹ PFU/mL were mixed together at a 1:1 ratio as a phage cocktail. A total of 100 mL of phage cocktail in SM buffer was added with 0.02 M Na₂CO₃ (Sigma-Aldrich, Oakville, Ontario, Canada) and around 1.2—1.8% sodium alginate (Buchi, Switzerland), depending on nozzle sizes used for the encapsulation. After alginate was dissolved, the phage-alginate mixture was subject to encapsulation using a Buchi B-390 encapsulator (Buchi, Switzerland) with different nozzle sizes (200, 300, 450, 750, and 1000 μm) accordingly. At the same time, a clean beaker containing 200 mL of 1.8% CaCl₂ (Sigma-Aldrich, Oakville, Ontario, Canada) with a low-rate spinning stir bar was used to catch and harden the resulting phage-encapsulated beads from the encapsulator. After solidifying, the beads were separated from the solution and washed with SM buffer (three times) to remove any free phages. The beads were stored in the SM buffer at 4 °C for further experiments.

Polylactide was obtained from NatureWorks (Minnetonka, MN, USA). Gelatin from porcine skin (type A), Span 80, poly(vinyl alcohol) (product no 363138; the molecular weight was 31,000–50,000 g/mol and the hydrolysis degree was 98–99%), beeswax, Folin–Ciocalteu reagent, gallic acid and diiodomethane were acquired from Sigma-Aldrich (Poznan, Poland). Sodium alginate was purchased from BÜCHI Labortechnik AG (Flawil, Switzerland). Dichloromethane and glycerol were supplied from Avantor Performance Materials Poland S.A. (Gliwice, Poland). Sodium carbonate and ethyl alcohol were purchased from Stanlab (Lublin, Poland). Sodium hydroxide was acquired from Chempur (Piekary Slaskie, Poland). Cottonseed oil was provided by Alston Nova, S.L. (Barcelona, Spain). All used chemicals were of analytical grade. The 2% hydroglycolic Calendula officinalis flower extract (propylene glycol/water (80:20)) was obtained from Provital S.A. (Barcelona, Spain) and its total polyphenol content was assessed with the use of the Folin–Ciocalteu method. The absorbance was measured at 725 nm using a UV–VIS spectrophotometer and the results were calculated as gallic acid equivalents (mgGAE/mL). The total polyphenolic content of the extract was 206.6 ± 3.6 mgGAE/mL.