Multiwave 3000 microwave reaction system

MAE was carried out using multiwave-3000 microwave reaction system (Anton-Paar, Germany, GmbH) consisted of 8 closed extraction vessels equipped with infrared temperature sensor, vessel mark sensor, controllers and a magnetic stirrer at the base. For extraction, 1 g of the powdered root sample was dissolved in different volumes and concentrations of methanol at different pH values (Supplementary Tables 1, 2). The mixture was placed in closed vessel extracting chamber inside the microwave reaction system. Microwave power at different levels and time periods (Supplementary Tables 1, 2) was applied according to the model design and the filtered extract was stored at −20 °C. All dependent variables (responses) were measured within two weeks from the storage time.

Under magnetic stirring 1mL of aqueous solution of Cd(OAc)₂ (5.32mg/mL) was added to 7.6mL of Milli-Q water. Then 1mg of HWRGWVC heptapeptide (abbreviated HWR peptide) and 50μL of 60mg/mL mercaptosuccinic acid were added. Preparation proceeded by adding 90μL of 1M NH₃ and 150μl of 4.43mg/mL Na₂TeO₃. Reductions of samples were conducted by adding 4mg of NaBH₄. Solutions were closed in vials and added into the Multiwave 3000Microwave Reaction System (Anton Paar, Graz, Austria) for 20 min at 110 °C and power of 300 W. To remove the excess HWR peptide, the QDs were filtered by the Amicon Ultra 3K device (Millipore, Billerica, MA, USA).