Penicillin streptomycin pen strep

Trypsin-EDTA, Dulbecco’s modified Eagle’s medium (DMEM/F-12 (1:1)), fetal bovine serum (FBS, 10%), penicillin-streptomycin (PEN-STREP), zinc nitrate hexahydrate, cadmium nitrate tetrahydrate and Pb(NO₃)₂ were purchased from Sigma. Commercial Pb, Cd and Zn standards (1 g l⁻¹) were prepared from Merck. Graphene quantum dots (blue luminescent) were purchased from Sigma-Aldrich. The other chemicals which were needed for doing this project were available in archive of our laboratory which had been purchased from Sigma or Merck. Doubly distilled water was used wherever water was needed. A phosphate buffer solution (PBS, 0.01 M) was prepared from Na₂HPO₄ and its pH was adjusted at 7.4 by the use of H₃PO₄ and NaOH.

A375-human melanoma cell line (ATCC^® CRL-1619 ^TM) and MCF7—human breast adenocarcinoma cell line (ATCC^® HTB-22^TM) were purchased from the American Type Culture Collection (ATCC, Manassas, VA, USA); HaCaT—human keratinocytes were kindly provided by the University of Debrecen (Debrecen, Hungary). A375 and HaCaT cells were cultured in high glucose Dulbecco’s Modified Eagle’s Medium (DMEM; Sigma-Aldrich); MCF7 cells were cultured in Eagle’s Minimum Essential Medium (EMEM; ATCC). Each cell line was supplemented with 10% fetal bovine serum (FBS; Gibco, Thermo Fisher Scientific) and 1% antibiotic mixture (Penicillin/Streptomycin—Pen/Strep, 10,000 IU/mL; Sigma-Aldrich). The cells were kept under standard conditions (37 °C and humidified atmosphere containing 5% CO₂).

6 human cancer cell lines were selected to be investigated in vitro; H460 (large cell lung cancer), MiaPaCa2 (pancreatic carcinoma), DU145 (prostate carcinoma), MCF7 (breast adenocarcinoma), U87 (brain glioblastoma) and HEPG2 (liver carcinoma). All cell lines were acquired from the American Type Culture Collection (ATCC), and were routinely tested for mycoplasma. All cell lines have also been authenticated by ATCC using Short Tandem Repeat (STR) Screening. Cells were incubated at 37 °C in 5% CO₂, and all tissue culture was performed in a Class II laminar flow cabinet (Thermo, US). All cell lines, except for MiaPaCa2, were cultured in Dulbecco’s Modified Eagle Media (DMEM) (Sigma, US), supplemented with 10% Foetal Bovine Serum (FBS) (Sigma, US) and 1% Penicillin Streptomycin (Pen-Strep) (Sigma, US). MiaPaCa2 cells were incubated in High Glucose DMEM media, supplemented with 10% FBS, 1% Pen-Strep, and 0.2% Sodium Pyruvate. Cells were passaged every 2–3 days to maintain exponential grown.
NPs used for this study were SPIONs with a 5 nm diameter, acquired from Sigma, US (product number 725331), suspended in H₂O at a concentration of 5 mg/ml, with the molecular weight of Fe₃O₄ being 231.53 g/mol. For the purpose of this study, all assays were performed at a SPION concentration of 23.5 μg/ml, which was determined as being within the range investigated by Kirakli et al. [56 (link)].