Glycerine

Medium molecular weight CS, degree of deacetylation~75% (molecular weight: 100,000–300,000 g/mol), and PVA, 13,000–23,000 g/mol, 87–89% degree of hydrolysis were purchased from Acros Organics BVBA (Geel, Belgium). Glutaraldehyde (GA) 50% in aqueous solution, anhydrous ≥98.0% magnesium sulfate (MgSO₄), and glycerine ≥99.7% were purchased from VWR International. Zinc oxide nanopowder (ZnO, 99+%, 10–30 nm) was obtained from US Research Nanomaterials, Inc. (Houston, TX, USA). Human dermal fibroblasts cell line (HDFa), Dulbeco’s modified Eagle’s Medium (DMEM), 10% fetal bovine serum (FBS), antibiotics (streptomycin/penicillin), non-essential amino acids, phosphate-buffered saline (PBS), and trypsin-EDTA, necessary for in vitro cytotoxicity assay, were purchased from Thermo Fisher Scientific (Waltham, MA, USA). 3-(4,5-Dimethyl-2-thia zolyl)-2,5-diphenyl-2H-tetrazolium bromide was obtained from Merck Millipore (Darmstadt, Germany). Freeze-dried stains (Staphylococcus aureus-ATCC 25923, Escherichia coli-ATCC 11775, Klebsiella pneumonia-ATCC BAA–1705, and Pseudomonas aeruginosa-ATCC 10145) were purchased from ATCC (Manassas, VA, USA). Chapman agar (mannitol salt agar) was purchased from Oxoid (Hampshire, United Kingdom) and MacConkey agar from G & M Procter Ltd. (Perth, UK). All other chemicals used were of analytical grade.

MUCAS was produced following the procedures specified in the MUCAS patent (patent application pending in the name of IML red GmbH; application number: EP19165015.9). The main ingredients of MUCAS were: mucin from porcine stomach type II (Sigma-Aldrich, USA), Middlebrook 7H9 powder (BD, USA), salmon DNA (Sigma-Aldrich, USA) and glycerine (VWR Chemicals, USA). Each MUCAS LOT was controlled for the absence of MTB DNA by performing XP-Ultra tests from 1 ml MUCAS from three different aliquots following the instructions of the manufacturer.