Acrylamide aam

Acrylamide (Aam) (> 99%, Sigma Aldrich), poly(ethylene glycol) diacrylate (PEG‐DA) (Sigma Aldrich), 2‐hydroxy‐2‐methylpropiophenone (HMPP) (Sigma Aldrich), and an aqueous glycerol solution (8 wt%) (Sigma Aldrich) were mixed to prepare hydrogel precursor solution in a weight ratio of 150:3:4:1150. An ion gel precursor solution was prepared by mixing butyl acrylate (BA) (Sigma Aldrich), poly(propylene glycol) diacrylate (PPG‐DA) (M_n = 800, Sigma Aldrich), HMPP (Sigma Aldrich), and 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM:TFSI) (>98%, Sigma Aldrich) in a weight ratio of 60:1:1:40. The hydrogel precursor solution (440 µL) was poured in a stainless‐steel mold (10 mm x 30 mm x 2 mm) and UV irradiation (72.8 mW, 365 nm) was applied for 100 s. The ion gel precursor solution (280 µL) was poured on the hydrogel layer in the mold. UV was irradiated for 120 s on the ion gel precursor.

Acetone (Sigma-Aldrich; ≥99.5%), ethanol (Sigma-Aldrich; ≥99.5%), methanol (Sigma-Aldrich; ≥99.9%) remained employed as received without additional purification. For hydrogel synthesis, acrylamide (AAm, Sigma-Aldrich; ≥99.9%), N-Isopropylacrylamide (NIPAAm, Sigma-Aldrich; ≥99%), sodium alginate (SA, Sigma-Aldrich; ≤15.5%), 2-hydroxy-4 ′ -(2-hydroxyethoxy)-2-methylpropiophenone (photo-initiator or PI, Sigma-Aldrich; ≥97.5%), N, N ′ -Methylenebis(acrylamide) (MBAA, Sigma-Aldrich; ≈99%), ammonium persulfate (APS, Sigma-Aldrich; ≈98%), N,N,N ′ ,N ′ -Tetramethylethylendiamin (TEMED, Sigma-Aldrich; ≈99%), and deionized (DI) water (Milli-Q pore; 18.2 M Ω ) were used as received without additional modification. Poly(dimethylsiloxane) (PDMS) (Sylgard 184, Dow Corning) was prepared as prescribed with the 10:1 base-to-catalyst ratio. The adhesive (Scotch) tape was purchased from 3M.

Natural polymers obtained from Sigma-Aldrich, Darmstadt, Germany and methacrylated using the protocol described in [65 (link)] were used to obtain the hydrogels: high-molecular-weight chitosan (CsMa, Mw = 310.000–375.000 Da, 21.2% degree of methacrylation); gelatin (GelMa, from porcine skin, Mw = 100,000 Da, 62.4% degree of methacrylation); dextran from Leuconostoc spp. (DexMa, Mw = 450.000–650.000 Da, 15.1% degree of methacrylation); and xanthan from Xanthomonas campestris (XMa, Mw = 458,000 Da, 9.5% degree of methacrylation). The monomers (acrylamide -Aam and N,N’-methylenebis (acrylamide), bisAam)) and the photoinitiator (Irgacure 2959 (2-Hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone)) were purchased from Sigma-Aldrich, Darmstadt, Germany. Absolute ethyl alcohol, the dialysis membrane (Mw = 12,000–14,000 Da), isopropanol, Dulbecco’s Modified Eagle’s Medium/Nutrient Mixture F-12 Ham, Hanks’ Balanced Salt Solution, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium), and PBS (phosphate-buffered saline, pH = 7.2) were provided by Sigma-Aldrich, Darmstadt, Germany. Other essential elements used in the study are the antitumor drug doxorubicin hydrochloride (DOX, provided by Sigma-Aldrich, Darmstadt, Germany) and epidermal carcinoma cells A431 (acquired from the European Collection of Cell Cultures (ECACC), Salisbury, United Kingdom).

The reagents for PNVF and PAAm networks are as follows [29 (link)]. N-vinyl formamide (NVF; Sigma-Aldrich, St. Louis, MO, USA: 98%) monomer was purified by distillation under vacuum at 80 °C and stored at −10 °C before polymerization. A novel cross-linker, 2-(N-vinyl formamide) ethyl ether (NVEE; liquid of density of 1.3 g/mL), was synthesized and characterized by our previously reported procedure [10 (link),29 (link),44 (link)]. The monomer, acrylamide (AAm; Sigma-Aldrich: 99+%) and the cross-linker, N,N’-methylenebisacrylamide (BIS; Sigma-Aldrich, St. Louis, MO: 99+%) are electrophoresis grade and were used as received. Hydrolysis was carried out using 0.1 M NaOH (Fisher Scientific, Pittsburgh, PA, USA). The initiator, 2,2′-Azobis[2 -(2-imidazolin-2-yl) propane] dihydrochloride (VA-044; Wako Pure Chemical Industries, Ltd., Osaka, Japan), was used as received. The different pH solutions were made by dilution of stock solutions of HCl (Fisher Scientific, Pittsburgh, PA) and of NaOH.

Silica nanoparticles of diameters about 370 nm were synthesized in our laboratory. HF, toluene solution and ethanol were obtained from Aladdin (Shanghai, China). Dimethyl sulfoxide (DMSO), MTT, glutaraldehyde, Triton-X100, laminin, acrylamide (AAm), N,N’-methylenebisacrylamide (MBA) and 2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP) were acquired from Sigma (USA). The PEDOT:PSS suspension (Clevios PH1000) was bought from Heraeus Electronic Materials GmbH (Leverkusen, Germany). Phosphate buffered saline (PBS), fetal bovine serum (FBS), horse serum (HS), NGF, DAPI, RPMI1640 and penicillin–streptomycin were obtained from Gibco (Rockville, USA). Donkey anti-mouse IgG (H + L) Alexa Fluor 555 secondary antibodies were obtained from Invitrogen (Carlsbad, USA). Mouse anti-βIII-tubulin primary antibodies were achieved from Abcam (UK). DAKO fluorescence mounting medium was purchased from DAKO (Denmark). PC12 cell line was from Chinese Academy of Sciences. A Millipore Milli-Q system (Millipore, Bedford, MA) was used to provide deionized water which owns a resistivity higher than 18 MΩ·cm.

Fe(NO₃)₃∙9H₂O (≥98%), Co(NO₃)₂∙6H₂O (98%), and acrylamide (AAm) (≥98%) were purchased from Sigma-Aldrich Chemie GmbH, Steinheim, Germany and were used without additional purification. Benzene (chemically pure, Chimmed, Moscow, Russia) and diethyl ether (chemically pure, Chimmed, Moscow, Russia) were purified and distilled according to the standard procedure.

For the synthesis of the MNP, the chemicals iron(III) chloride hexahydrate (FeCl₃·6H₂O, p.a., ≥99%, Sigma-Aldrich, Darmstadt, Germany), iron(II) chloride tetrahydrate (FeCl₂·4H₂O, p.a., ≥98%, Sigma-Aldrich, Darmstadt, Germany), ammonium hydroxide (NH₄OH, ACS reag., 28–30%, Sigma-Aldrich, Darmstadt, Germany), and lauric acid (C₁₂H₂₄O₂ > 98%, FCC, Sigma-Aldrich, Darmstadt, Germany) were used. The chemicals acrylamide (Aam, ≥99%, Sigma-Aldrich, Darmstadt, Germany), N,N′-methylenebisacrylamide (BIS, 99%, Sigma-Aldrich, Darmstadt, Germany), ammonium peroxodisulfate (APS, ≥98%, AppliChem, Darmstadt, Germany), and N,N,N′,N’-tetramethylethylene-diamine (TEMED, 99%, Sigma-Aldrich, Darmstadt, Germany) were used for the synthesis of the acrylamide hydrogel. Technical grade polypropylene (PP) pellets (Moplen HP561R) were purchased from LyondellBasell Industries N.V. (Rotterdam, Netherlands). Agarose (Carl Roth, Karlsruhe, Germany) was used to prepare a tissue-like gel environment in which the inductive heating experiments were carried out. For the cytotoxicity tests, RPMI cell culture medium (21875-034, Life Technologies, Carlsbad, CA, USA) and CellTiter-Glo 2.0 assay (G7570, Promega, Madison, WI, USA) were used.