Time Release and Thermal Stability of Aloe vera (Aloe barbadensis) Gel Loaded PLGA Nanoparticles and Its Antioxidant Activity

Abstract. Nano-encapsulation is an attractive method for preserving bioactive compounds for selective release during digestion and heat processing, respectively. Hence, the aim of this study was to encapsulate Aloe vera gel (liquid form vs. powder) by the ultra-sonication-solvent evaporation techniques using poly lactic-co-glycolic acid (PLGA) and to assess the physico-chemical characteristics, antioxidant activity and thermal stability of the formed nanoparticles (NP). The average hydrodynamic diameter of the PLGA unloaded (UNP) and liquid Aloe vera gel (LNP) vs. powder Aloe vera gel (PNP) loaded NP was 102.9 ± 0.35, 221.4 ± 0.86 and 146.2 ± 1.06 nm, respectively and varies significantly (p<0.05) from each other. The PDI and zeta potential for NP were 0.2,0.3 and 0.2 and -60, -21.9 and -28 mV, respectively. The TEM images showed all the NP was spherical shape with smooth surface. The encapsulation efficiency for PNP and LNP was 86 and 67 %, respectively. The release study of PNP and LNP showed constant release at a rate of 0.002/min and 0.0025/min over the entire period from the polymer matrix, respectively. The antioxidant potentiality of the unloaded powder Aloe vera gel (UP), PNP and LNP were 54 ± 0.5, 51 ± 2 and 50 ± 1.5 % in reduction of DPPH activity, respectively. The DSC thermogram showed the UP melts at 115°C while the PNP at 324°C, hence achieves thermal stability with encapsulation. Therefore, the study concludes that encapsulating with PLGA will improve the Aloe vera gel application, bioavailability and stability in various food systems.