Turmeric extract-loaded polyvinylpyrrolidone spherical submicron particles produced using electrohydrodynamic atomization: their physico-chemical properties and antioxidant activity

Abstract

We synthesized novel spherical submicron particles of turmeric extract (TUR)-loaded polyvinylpyrrolidone (PVP) using the electrohydrodynamic atomization technique. The SEM images show the formation of spherical submicron particles for the mass ratio of TUR and PVP ≥ 2/5. Their average particle diameter increases with the TUR mass increment, which is induced by the conductivity, viscosity, and surface tension decrements of precursor solutions. Furthermore, the flow rate (Q) and conductivity (σ)-dependent average particle diameter (D) is in line with the particle diameter universal control given by log(D) = 0.320 log (Q/σ) − 1.135. From the FTIR spectra, the submicron particles clarify the intermolecular modes of PVP and TUR consisting of the vibration and the stretching modes at the high and low wavenumbers, respectively. Notably, the mass ratio of PVP and TUR modifies hydroxyl vibration modes. The XRD patterns show the dominant curcumin polycrystallines in the TUR particles, which are not observed in the PVP-TUR submicron particles. This result indicates the structural deformation of TUR between PVP bundles. From DSC measurements, the glass transition of PVP-TUR submicron particles (54.3 °C) is between that of PVP and TUR, agreeing the Gordon–Taylor formulation. Their melting point (166.4 °C) is lower than those of PVP and TUR, indicating the Schröder–van Laar relation. The relative mass changes of PVP-TUR submicron particles are higher than that of both PVP and TUR. Then, IC50 of the PVP-TUR submicron particles linearly decreases from (16.4 ± 3.9) to (10.5 ± 2.9) μg ml−1 with the TUR mass increment, implying the antioxidant activity enhancement with increasing the TUR mass.