Preparation, characterization, and induction of cell apoptosis of cocoa procyanidins-gelatin-chitosan nanoparticles.

Cocoa procyanidins (CPs)-gelatin-chitosan nanoparticles were fabricated based on the procyanidin-protein and electrostatic interactions, with an objective to enhance the stability and bioactivity of CPs. The CPs were purified using chromatographic methods and analyzed using HPLC equipped with a fluorescence detector (FLD) and mass spectrometer (MS). The purified CPs had a purity of 53.1% (w/w) and contained procyanidin oligomers (from monomer to decamers) and polymers, with polymers being the predominant component (26.4%, w/w). Different CPs-gelatin-chitosan mass ratios were tested to investigate the effects of formulation on the nanoparticle fabrication. Using CPs-gelatin-chitosan mass ratio of 0.75:1:0.5, the resultant nanoparticles had a particle size of 344.7 nm, zeta-potential of +29.8 mV, particle yield of 51.4%, loading efficiency of 50.1%, and loading capacity of 20.5%. The CPs-gelatin-chitosan nanoparticles were spherical as observed by scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) suggested that the primary interaction between the CPs and gelatin was hydrogen bond and hydrophobic interaction, while electrostatic interaction was the main binding force between chitosan and CPs-gelatin nanoparticles. Nanoencapsulation of the CPs significantly improved the stability of the CPs at 60°C. The CPs-gelatin-chitosan nanoparticles showed the same apoptotic effects at lower concentrations in human acute monocytic leukemia THP-1 cells compared with the CPs in solution.