Sonorex rk 106

Graphene (G3, 1.00 g) and l-DOPA (2.00 g) were dispersed/dissolved
in the solution of Tris-base in water (10 mM) (pH = 8.5, 1.0 L). The
reaction mixture was placed in a round-bottom flask (2 L) equipped
with a reflux condenser and a mechanical stirrer and sealed.^{53 (link)} After that, the polymerization reaction was
initiated thermally and continued for 48 h at 60 °C using a heating
mantle. Upon processing, the dispersion changed color from yellow
to brown. The postreaction mixture was centrifuged (10,000 rpm, 30
min), and the resulting black powder (1.20 g),^{58 (link)} that is, poly(l-DOPA)-functionalized graphene
(G3@PDOPA), was washed with water (1.0 L) and dried at 80 °C
for 48 h. Exactly the same procedure was applied for the blank experiments,
that is, the samples composed only from l-DOPA or only from
graphene G3 flakes.
To evaluate the hydrophilic/hydrophobic
behavior of graphene and G3@PDOPA, the corresponding aqueous dispersions
(2 mg mL^–1) were prepared. After weighing out the
appropriate amounts of graphene and water, the mixtures were ultrasonicated
(Bandelin Sonorex RK 106, 35 kHz, rated power of 480 W) for 10 min.
Additionally, in order to evaluate the dispersion effect of l-DOPA operating via the optional noncovalent modifications, we also
have prepared the graphene dispersion but disabling polymerization
of l-DOPA.

After samples were gently air-dried in a drying oven at 30 °C for ≤ 7 days until stable mass was attained and shortly stored under cool, dry and dark conditions, volatile compounds of basil leaves were extracted according to the following procedure: 100 mg (± 2 %) of dried and powdered (3 intervals of 10 seconds at 15,000 rpm via Tube Mill control, IKA^®, Staufen, Germany) basil leaves from two basil pots (of the same cultivar, light treatment, harvest date and experimental block) were transferred into 2 mL screw cap micro tubes (Sarstedt AG & Co. KG, Nümbrecht, Germany) including two steal grinding balls (Ø 2 mm) and homogenized in 1.0 mL of high-performance liquid chromatography grade isooctane (Th. Geyer, Renningen, Germany) [containing 1:2000 (v/v) carvacrol as internal standard] for 10 minutes at 30 rps with a ball mill (MM400, Retsch^®, Haan, Germany). After 10 minutes of ultra-sonification (Sonorex RK 106, Bandelin electronic GmbH & Co. KG, Berlin, Germany) and 10 minutes of centrifugation at 13,000 rpm (Heraeus™ Labofuge™ 400 R, Thermo Scientific™, Osterode, Germany) at 22 °C respectively, the supernatants were transferred into GC-vials and stored at -70 °C until analysis (N = 256 samples).

The individual bead samples prepared from 120 g of NaALG dispersion were obtained through external ionic gelation [25 (link)]. Homogenized dispersion of NaALG (6%) was prepared by gradually swelling and dissolving NaALG in purified water for 15 min at room temperature, and subsequent homogenization using the Ultra-Turrax (T25 basic, IKA-Werke, Germany) at 13,000 rpm for 5 min. Air bubble elimination was ensured by an ultrasonic bath (Bandelin Sonorex RK 106, Germany) for 30 min. The homogenized dispersion was extruded through a 0.7 mm diameter needle at a flow rate 2.0 mL/min, into 50 mL of 1.0 M hardening solution (CuCl₂, ZnCl₂, CaCl₂ or their 0.5 M:0.5 M mixtures). Concentrations were selected on the basis of our previous pre-formulation studies [6 (link),42 (link)]. The distance between the edge of the needle and the solution’s surface was adjusted to 7.0 cm. Formed beads were immediately cured for 60 min, then thoroughly washed with purified water and dried in a cabinet drier (HORO-048B, Dr. Hofmann GmbH, Germany) at 25 °C for 24 h. The designation of the samples corresponded with the type of cross-linking ions (see Table 1).