2 2 azobisisobutyronitrile

Glucose, glucose oxidase (GOD, 26,820 unit(U)/g-solid, from Aspergillus niger), coumarin 6 (C6), 3-aminopropyltrimethoxysilane (APTMS), 3-Glycidoxypropyltrimethoxysilane (GPTMS), bovine serum albumin (BSA), iron chloride, poly(vinyl pyrrolidone) (PVP, M.W. ≈ 55,000), styrene, 2,2’-azobisisobutyronitrile (AIBN), sodium dodecyl sulfate (SDS), L-ascorbic acid, uric acid, and acetaminophen were purchased from Sigma-Aldrich Chemical Co. (Seoul, Korea). Pt(II) meso-tetra (pentafluophenyl) porphine (PtP) was obtained from Frontier Scientific Co. (Logan, UT, USA). Other chemicals such as ethanol, tetrahydrofuran (THF), hydrochloric acid, sodium hydroxide, sodium phosphate, sodium chloride, and sodium bicarbonate were of analytical grade and used without further purification.

Styrene, maleic anhydride (MA), p-divinylbenzene (DVB) and 2,2’-azo-bis(isobutyronitrile) (AIBN) were purchased from Sigma-Aldrich (Prague, Czech Republic). Styrene was distilled, MA was resublimed and AIBN was recrystallized from methanol prior to use. Ethyl acetate, ethanol and acetone of analytical grade were obtained from Lach-Ner (Neratovice, Czech Republic). Acetonitrile (ACN) and water of HPLC grade were purchased from VWR (Prague, Czech Republic). Phosphate buffered saline (PBS) solution (pH 7.4) was prepared from tablets supplied by Sigma-Aldrich (Prague, Czech Republic) according to the manufacturer’s instructions. Fetal bovine serum (FBS) was purchased from Sigma-Aldrich (Prague, Czech Republic). Cell culture medium (CellGRO) and AlamarBlue Assay were purchased from ThermoFisher Scientific (Prague, Czech Republic), 24-well plates were from TPP (Prague, Czech Republic).

The water-soluble Chit (weight average molecular weight, MW = 162,000 g/mol; degree of deacetylation 88.2%), containing lactate and phosphates counterions, was acquired from Shandong AK Biotech Co., Ltd. (Jinan, China) and used without further modification. The PNIPAM was synthetized in our laboratory (MW = 3200 g/mol, PDI = 1.11), using a previously published protocol [47 (link)]. Potassium persulfate (KPS, 99%) and poly(ethylene sulfonic acid sodium salt) (PESNa), 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl] pentanoic acid as the chain transfer agent (CTA) and 2,2-azobis(isobutyronitrile) (AIBN) have been provided by Sigma-Aldrich (Sigma Chemical Co.; St. Louis, MO, USA). For stock solutions was used ultrapure water (conductivity 0.552 μS/cm) obtained by an EVOQUA Ultra Clear TPTWF (Evoqua Water Technologies LLC; Barsbüttel, Germany). DNA as sodium salt, derived from salmon sperm, with an average molecular weight MW = 75,000 g/mol (i.e., 50,000–100,000 g/mol) which corresponds to approximately 113 bp was received from Acros Organics (Geel, Belgium).

AZM, ERY, and tilmicosin (TM) were obtained from Sigma-Aldrich (USA). Oleandomycin (OLE), tylson (TYL), and clarithromycin (CLA) were obtained from Dr. Ehrenstorfer (Germany). Dopamine (DA), streptomycin (STM), gentamicin (GM), tetracycline (TC), neomycin (NM), and thiamphenicol (TAP) were purchased from Probe Biotechnology LLC (China). The chemical molecular structures of these substances are shown in Fig 1. AZM-dispersible tablets (250 mg) were obtained from a local pharmacy. Ethylene glycol dimethacrylate (EGDMA), methacrylic acid (MAA) and 2,2-azobisisobutyronitrile (AIBN) were obtained from Sigma-Aldrich (USA). In order to remove the polymerization inhibitor, MAA and EGDMA were purified by distillation in vacuum under nitrogen protection then stored at 4°C before use. AIBN was recrystallized from hot methanol and dried in a vacuum. AB (purity > 99.99%) was obtained from Strem Chemicals (USA). Paraffin oil and graphite powder were obtained from Sinopharm Chemical Reagent Co., Ltd. (China). Acetonitrile and methanol were purchased from KeMiOu Chemical Reagent Co. (China). All other chemicals were of analytical grade and obtained from Sinopharm Chemical Reagent Co., Ltd. (China). All solutions were freshly prepared with ultrapure water.

Methacrylic acid (MAA) [79–41–4] (cat. no. M0782, Sigma-Aldrich, Saint Louis, MO, USA) and divinyl benzene (DVB) [97–90–5] (cat. no. 414565, Sigma-Aldrich) were filtered through an extraction column composed of 500 mg of aluminium oxide (Sigma-Aldrich, Saint Louis, MO, USA) for separation prior to use, in order to remove stabilizers. 2,2′-Azobisisobutyronitrile [78–67–1] (AIBN) was used as obtained from Sigma-Aldrich. All other chemicals were of analytical reagent grade. Solutions were prepared with ultrapure water (Milli-Q, Merck KGaA, Darmstadt, Germany). Screen-printed cells (SPC) with graphite working electrode (WE), graphite auxiliary electrode (AE), and Ag ink quasi-reference electrode (RE) on polyester support were commercially available (EcoBioServices s.r.l., Florence, Italy). Each cell was cut out from a strip of ten screen-printed cells to a width of 0.9 cm.