Sodium

CNOs were obtained according to the method proposed by Kuznetsov,^{72 (link)} in which diamond nanoparticles (NDs, Carbodeon µDiamond Molto) with a diameter of 4.2 ± 0.5 nm and a ND content of ≥97 wt% were annealed. All the chemicals and solvents were commercially available and used without further purification: nanodiamond powder (µDiamond®Molto, Carbodeon); 1,2-dicyanobenzene (∼98%, Sigma-Aldrich); ammonia solution (25% pure p.a., Sigma-Aldrich); maleimide (∼99%, Sigma-Aldrich); tetrahydrofuran (pure p.a., Avantor); 2-propanol (pure p.a., Avantor); acetone (99.5% pure p.a., Avantor); 2-mercapto-4-methyl-5-thiazoleacetic acid (∼98%, Sigma-Aldrich); zinc chloride (≥99%, Sigma-Aldrich); nickel(ii) chloride (∼98%, Sigma-Aldrich); copper(ii) chloride (∼97%, Sigma-Aldrich); hydrochloric acid (35–38% pure p.a., Avantor); sulphuric acid (95% pure p.a., Avantor); sodium chloride (pure p.a., Avantor); aluminium powder (∼99.99%, Avantor); sodium (Sigma); 1-octanol (≥95%, Sigma-Aldrich); potassium permanganate (Avantor); dimethyl sulphoxide (DMSO, pure p.a., Avantor); and methanol (99.5% pure p.a., Avantor).

Neural stem cells were cultured in alginate (Sigma-Aldrich, St. Louis, MO, USA) scaffold for 7 days at a concentration of 4,000 cells/well. The sterile sodium alginate was dissolved in DMEM/F12 (alginate concentration 0.25%) and resuspended with 4,000 cells in 40 µL. The solution was then transferred to 96-well plates and 100 µL of chilled CaCl₂ (Sigma-Aldrich) at 10 mM was added, and the cells were kept on ice for 10 minutes. Subsequently, 50 µL of the suspension were removed and the neural stem cells culture media and laminin at 5 µg/mL was added to each well. For releasing the encapsulated neural stem cells, the scaffold was washed with PBS and a solution containing 15 mM sodium citrate and 150 m MNaCl (Sigma-Aldrich) was added and the cells were incubated in 37℃ for 1 hour [14 (link)].