2.5. Drug loading and entrapment efficiency

The drug loading and encapsulation efficiency were determined by analyzing the NPs spectrophotometrically using Lambda Bio 20 UV/VIS Spectrophotometer (Perkin Elmer, USA). The amount of Cur, Quer and Asp present in the nanoparticles was estimated as follows: a known amount of NPs (1 mg/mL) was dispersed in the mixture of double distilled water: ethanol (1:1) solution by stirring the sample vigorously and the absorbance of the solution was measured at 265, 373 and 426 nm for Asp, Quer and Cur, respectively, and the amount of drug present was calculated from a previously drawn calibration curve of concentration vs. absorbance with different known concentrations of the drugs. The percent drug loading (%DL) and entrapment efficiency (%EE) were calculated using the formulas as given below. All the measurements were performed in triplicate.