Preparation and characterization of plant based lipophilic colorants as water soluble nanoparticle

Response surface methodology (RSM) was used in this study to obtain empirically significant (p<0.05) models predicting the mean particle size, PDI of the prepared nanodispersions of alizarin (a plant based pigment), extracted from Rubia tinctorum L. roots, as a function of organic to aqueous phase addition rate, emulsifier concentration and polymer concentrations. The mentioned processing variables were then optimized to produce the nanodispersions with minimum particle size and maximum homogeneity (minimum PDI). The significant (p<0.05) correlation between the process parameters and physical characteristics of alizarin nanodispersions through second order polynomial models were obtained. It was demonstrated that mixing the organic phase containing alizarin and the aqueous phase containing Tween 20 as emulsifier in concentration of 3.5 ml and PVP as polymer with concentration of 240 mg with the rate of 0.45 ml/min would give the most desired alizarin nanodispersions with minimum particle size (45.15 nm) and PDI (0.1898). No significant differences observed between the experimental and predicted values of response variables, confirmed the adequacy of models.