2.5. ZnO Capped DOX@MSCNs

DOX, 20 mg, was dispersed in 40 mL of pH 7.4 PBS followed by adding 80 mg MSCNs-COOH. The mixture was shaken at 25 °C for 24 h. The DOX-loaded MSCNs (DOX@MSCNs) were collected by centrifugation at 8000 r/min for 5 min and dried under vacuum. The absorbance of the supernatant was measured by UV-vis spectrophotometer at 480 nm, the loading amount (mg/g) and efficiency (%) of DOX were calculated by the following Equations (1) and (2):

The above DOX@MSCNS were dispersed in 10 mL aqueous solution containing 50 mg ZnO-NH₂ QDs and 60 mg EDC. After stirring at room temperature for 5 h, the precipitate was centrifuged (5000 r/min, 5 min) and washed several times with deionized water until the supernatant became transparent. The ZnO-capped drug loaded particles (DOX@MSCNs-ZnO) were collected after freeze-drying. The ZnO-capped MSCNs (MSCNs-ZnO) were prepared using the same synthetic approach as DOX@MSCNs-ZnO.