“…In vitro drug release from ENZ, ENZ-PLGA NPs, ENZ-PLGA-PSAR NPs, ENZ-PLGA-PSAR-TPGS NPs were performed in PBS at physiological conditions maintaining 37 °C and pH 5.5 by utilizing dialysis tube process, in order to predict the in vivo behaviour. PBS pH 5.5 buffer was considered due to acidic nature of ENZ having pKa value of 4.16 and PSAR's tendency to swell and release drugs in acidic environment present in tumour [ 74 ]. The observed pattern of release in optimized ENZ-PLGA-PSAR-TPGS NPs had a higher and sustained release,88.5 ± 22.5 % in 12 h, compared to pure drug which had poor pattern of release and ENZ-PLGA NPs having 83.2 ± 15.34 % in 4 h and ENZ-PLGA-PSAR NPs having release of 83.2 ± 23.4 % in 10 h. From Fig.…”