Preparation and characterisation of triangular pyramid-shaped puerarin and aspirin microparticles with nanostructures

A new class of triangular pyramid-shaped microparticles of puerarin and aspirin were prepared on copper substrate by using oil-in-oil microemulsion method which is simple and economical. The morphology and microstructure of the pyramid-shaped microparticles were characterised by field emission scanning electron microscopy. The results show that pyramid-shaped puerarin and aspirin, with coral reef-like morphology, resulted from the self-assemble of nanoparticles or nanorods. A possible formation mechanism was proposed and discussed.