Effect of operating conditions on size of catechin/β-cyclodextrin nanoparticles prepared by nanoprecipitation and characterization of their physicochemical properties

Nanoscale catechin/β-cyclodextrin inclusion complex (CA/β-CD IC) particles were prepared by nanoprecipitation method (absolute ethanol as precipitant). The effects of β-CD concentration, ethanol amount used for precipitating and ethanol dropping rate during precipitation on size of CA/β-CD IC particles were studied. Dynamic light scattering results indicated the above operating conditions have a significant effect on size of CA/β-CD IC nanoparticles. Nanoparticles can be further reduced to about 90 nm by adjusting operating parameters, such as reducing β-CD concentration, increasing amount of ethanol and decreasing ethanol drop rate. Inclusion ratio of CA/β-CD IC nanoparticles was about 71%. Fourier transform infrared spectroscopy results indicated that intermolecular hydrogen bond interactions maintain CA in cavity of β-CD. X-ray diffraction results showed the crystalline structure in nanoscale CA/β-CD IC was different from that in micro-size CA/β-CD IC. Differential scanning calorimetry and scanning electron microscopy results confirmed the formation of CA/β-CD IC nanoparticles. CA/β-CD IC nanoparticles displayed great storage stability and ionic strength stability, and exhibited excellent stability at pH 4–9. Release behavior of CA from CA/β-CD IC nanoparticles was controlled. The CA/β-CD IC nanoparticles have potential applications in nano-functional foods.