Agar powder

The potato cultivar Desiree (ZPC, the Netherlands) was propagated in sterile conditions in 1X MS medium including vitamins at pH 5.8 (Duchefa, the Netherlands), 0.4 mg/L thiamine hydrochloride (Sigma-Aldrich, USA), 2.5% sucrose and 0.8% agar powder (VWR, USA). Plants were cultured in vitro in a growth chamber at 19°C with a 16:8 h L/D photoperiod.

Methanol (Ceamed, Lda., Funchal), Folin and Ciocalteu’s phenol reagent (Biochem Chemopharma, Cosne-Cours-sur-Loire, France), sodium hydroxide p.a. (Eka, Netherlands), sodium acetate (Honeywell, Charlotte, CA, USA), sodium nitrite p.a. (Merck, Darmstadt, Germany), indigo carmine (labkem, Spain), potassium permanganate (Acofarma, Madrid, Spain), sodium carbonate anhydrous p.a., potassium chloride (Panreac, Spain), absolute ethanol and sulfuric acid 95–97% (Chem-Lab, Zedelgem, Belgium), gallic acid (GA), catechin (CAT), aluminum chloride (99%), and 2,2-diphenyl-1-picrylhydrazyl (DPPH), purchased from Sigma-Aldrich (St. Louis, MO, USA), were used as chemicals for the extractions and bioactive characterization of the extracts.
Agar Powder (VWR, Lutterworth, UK); amphotericin B solution (Sigma, USA); blank, kanamycin (K) 30UG, and penicillin G (P) 2IU discs (LIOFILCHEM, Roseto degli Abruzzi, Italy); D(+)-glucose monohydrate and yeast extract (Scharlau, Barcelona, Spain); dimethyl sulfoxide (DMSO) and Mueller-Hinton Agar (Merck, Germany); Nutrient Agar (Biolab, Budapest, Hungary); and Nutrient Broth and Peptone (Cultimed, Spain) were used as chemicals for antimicrobial characterization of the extracts.

All reagents used for Gr-Ag (3, 5 and 20 wt% Ag) hybrids synthesis were of analytical grade and used without further purification. Silver nitrate and sodium ascorbate were purchased from Merck (Darmstadt, Germany). The reagents used for the antibacterial assays and SEM preparation were acquired from Sigma-Aldrich Chemie GmbH (Steinheim, Germany). The Mueller-Hinton broth was acquired from Oxoid (Thermo Fisher Scientific Inc., Kandel, Germany), the agar powder was acquired from VWR Chemicals (VWR International, Darmstadt, Germany) and ciprofloxacin of 98% purity was acquired from Alfa-Aesar (Thermo Fisher Scientific Inc., Kandel, Germany). The filter discs used in the agar-well diffusion method were Whatman AA grade (6 mm discs). The HEPA filter (DREISSNER-K0089DREIS) was bought from Germany. Colloidal silver nanoparticles (AgNPs) with the mean size of 9 nm were synthesized by Pure Life SRL (Suceava, Romania) and bought from a local drugstore.