Hexadecyltrimethylammonium bromide ctab

Hydrogen tetrachloroaurate-(III) trihydrate (HAuCl₄ ∙ 3H₂O, 99.99%), sodium borohydride (NaBH₄), Hexadecyltrimethylammonium bromide (CTAB, 96%), Cetyltrimethylammonium chloride solution (CTAC), ascorbic acid (AA) and Whatman^® qualitative filter paper, Grade 1 (Whatman no. 1) were purchased from Sigma-Aldrich (St. Louis, MO, USA). The synthetic RRWHRWWRR-NH₂ polypeptide (further noted as P2) was synthetized by Pierce Protein Biology, Thermo Fisher Scientific (Mt Prospect, IL, USA). All chemicals were of analytical grade, and all aqueous solutions were prepared using ultrapure water (resistivity~18 MΩ).

The reagents used in this study for CoFe₂O₄ synthesis are: CoCl₂•6H₂O (ACS reagent, 99% Sigma-Aldrich, St. Louis, MO, USA), FeCl₂•6H₂O (Fisher Scientific, laboratory reagent grade, Waltham, MA, USA), NaOH (ROTH 98%, Carl Roth, Karlsruhe, Germany), carboxymethyl cellulose (CMC) (Sigma-Aldrich, St. Louis, MO, USA). The materials used in the synthesis of the CoFe₂O₄@HaP nanocomposite are: Ethanol (99.8% ROTH, Carl Roth, Karlsruhe, Germany), Hexadecyltrimethylammonium bromide (CTAB, Sigma Aldrich, St. Louis, MO, USA), H₃PO₄ (85% ROTH, Carl Roth, Karlsruhe, Germany), NH₄OH (25% CHIM REACTIV SRL, Bucharest, Romania), Ca(NO₃)₂ (Sigma-Aldrich, St. Louis, MO, USA).

Tetraethyl orthosilicate (TEOS, CAS No. 78-10-4, puriss., 99% (GC)), Sigma-Aldrich, Budapest, Hungary), 1,2-bis(triethoxysilyl)ethane (BTEE) (96%; Sigma-Aldrich, St Louis, MO, USA), ethyl alcohol (CAS No. 64-17-5, 99.8%, VWR International, Budapest, Hungary), ammonium hydroxide (NH₄OH, CAS No. 1336-21-6, 25% (v/v), Reanal, Budapest, Hungary), hydrochloric acid (CAS No. 7647-01-0, Reanal, Budapest, Hungary), sodium carbonate (Na₂CO₃, CAS No. 497-19-8, ≥99%, Reanal, Budapest, Hungary)), and hexadecyltrimethylammonium bromide (CTAB) (CAS No. 57-09-0, ≥98%, Sigma-Aldrich) were used as received without any further purification.

Production of siderophores was determined by plate assay using chrome azurol S (CAS) (44 (link), 84 (link)) as previously described by Zajc et al. (19 , 35 (link)). CAS agar was prepared as follows: first, the mixture of 10 mL of 1 mM FeCl₃ × 6H₂O (Sigma-Aldrich, USA) in 10 mM HCl (Merck, Germany), 50 mL of CAS solution (Acros Organics, USA), and 40 mL hexadecyltrimethylammonium bromide (CTAB) (Sigma-Aldrich, USA) was prepared. Then, the medium of 30.24 g piperazine-N,N′-bis(2-ethanesulfonic acid) (PIPES) (Acros Organics, USA), 12 g 50% (wt/wt) NaOH (Sigma-Aldrich, USA), 20 g malt extract (Biolife, Italy), 1 g peptone (Merck, Germany), 20 g glucose, and 20 g agar in 900 mL deionized water was prepared. Both solutions were autoclaved separately and carefully combined after cooling. Plates were inoculated with 5 µL of the cell suspension or with one mycelial plug and incubated at 25°C for 14 days. After the incubation, yellow, orange, or pink discoloration around the colonies was observed and regarded as production of siderophores.
The relative amount of produced siderophore was calculated according to Zajc et al. (35 (link)):
$$\text{Amount\hspace{0.17em}of\hspace{0.17em}siderophore\hspace{0.17em}produced\hspace{0.17em}}=\left(\text{diameter\hspace{0.17em}of\hspace{0.17em}colony\hspace{0.17em}and\hspace{0.17em}discoloration\hspace{0.17em}zone}\right)\times {\left(\text{diameter\hspace{0.17em}of\hspace{0.17em}colony}\right)}^{-\text{1}}$$

All chemicals and oligomers were used as received without any modification or further purification. Hexadecyltrimethylammonium bromide (CTAB, 99%), Cetyltrimethylammonium chloride solution (CTAC, 25 wt% in H₂O), Potassium Iodide (KI, 99.5%), L-ascorbic acid (AA, 99%) and tetrachloroauric(III) trihydrate (HAuCl₄·3H₂O, 99.9%) were purchased from Sigma-Aldrich. All single-stranded oligonucleotides were synthesized and purchased from Integrated DNA Technologies, Inc. (IDT). All aqueous solutions were prepared using high-purity deionized water (18.2 MΩ cm⁻¹).

PHBV (ENMAT^TM Y1000P) was purchased from Tianan Biologic Materials (Ningbo, China) and provided in the form of pellets by NaturePlast (Ifs, France). As stated by the producer, the material is characterized by a density of 1.23 g/cm³, a melt flow index (MFI) of 5–10 g/10 min (190 °C, 2.16 kg), and a 3HV fraction of 2 mol.-%. The cerium (IV) oxide (CeO₂) nanoparticles, with particle size < 25 nm calculated by means of the Brunauer, Emmett, and Teller (BET) method, were provided by Sigma Aldrich (Madrid, Spain). According to the literature, the cytotoxicity (LC50) of CeO₂ was 1000 µg/mL measured in MCF7 cells [35 (link)], and the oral acute toxicity was (LD50) >5000 mg/kg measured in rats [36 ]. Hexadecyltrimethylammonium bromide (CTAB) (99%); 2,2,2-trifluoroethanol (TFE) (≥99%); and D-limonene (98%) were provided by Sigma Aldrich (Madrid, Spain).

Nanoparticles ZnO (nano-ZnO), TiO₂ (nano-TiO₂, mainly anatase form) and Ni (nano-Ni) were purchased from Sigma-Aldrich (USA). CAS numbers of used metal and metal oxide nanoparticles were: 1314-13-2 (nano-ZnO), 13463-67-7 (nano-TiO₂), 7440-02-0 (nano-Ni). The ENPs (the purity was around 99.5 %) were used as powder. The primary particle size of ENPs was as follows: nano-ZnO < 100 nm; nano-TiO₂ < 21 nm; nano-Ni < 100 nm. The size of ENPs was determined by transmission electron microscope (JEM-3010 TEM JEOL, Ltd., Japan). Surfactants (4-dodecylbenzenesulfonic acid—SDBS, hexadecyltrimethylammonium bromide—CTAB, triton X-100—TX-100) were purchased from Sigma-Aldrich (USA). All solutions were prepared using analytical grade reagents and HPLC grade water (POCH, Gliwice, Poland).