OBJECTIVE To optimize the formulation of huperzine A(HupA)-luteolin(Lut) loaded lipid cubic liquid crystalline nanoparticles(LCLCNs) and investigate their physicochemical properties.

METHODS The bottom-up method was used to prepare HupA-Lut loaded LCLCNs. Based on single-factor investigation of preparation process and formulation, the contents of glyceryl monooleate(GMO, X₁), poloxamer 407(P407, X₂) and Lut(X₃) were selected as the independent variables. The encapsulation efficiency of HupA(Y₁), and Lut(Y₂), and the average particle size(Y₃) as evaluation indicators. After linear normalization of these 3 indicators, central composite design-response surface methodology(CCD-RSM) was applied to optimize the LCLCNs formulation. Furthermore, physicochemical properties of LCLCNs, including particle size, optical properties and crystal structure were investigated.

RESULTS The optimal formulation consisted of 7.50% GMO, 1.07% P407, and 0.26% Lut. Under these conditions, the encapsulation efficiencies were (54.27±0.71)% for HupA and (90.89±1.18)% for Lut. The average particle size was (176.87±5.44)nm, with a polydispersity index of 0.118±0.022 and a Zeta potential of (−21.06±0.33)mV. The HupA-Lut loaded LCLCNs exhibited a spherical shape under transmission electron microscopy. Under a polarizing microscope, a dark field was observed without birefringence. The X-ray small-angle scatterometer revealed that the internal structure of the nanoparticles belong to a double rhombohedral(Pn3m) lattice.

CONCLUSION The response equation established by CCD-RSM demonstrates good predictability and can be used to optimize the formulation of HupA-Lut loaded LCLCNs. The prepared HupA-Lut loaded LCLCNs exhibit a Pn3m lattice structure, with small particle size, uniform distribution, and stable properties.