In Vitro Characterization of pRNA Dimers and Chitosan Nanoparticles

pRNA dimers and different chitosan nanoparticles were all morphologically characterized first by TEM. The suspension of pRNA dimers and dilutions of chitosan nanoparticles were dropped, respectively, on a copper grid to form a dry film at room temperature. Then the samples were negatively stained with 2% phosphotungstic acid, air-dried at room temperature once again, and observed using TEM.

The morphologies of pRNA dimers and chitosan nanoparticles were also observed by AFM. The pRNA dimers and dilutions of chitosan nanoparticles were spread onto a mica sheet, dried at room temperature, and observed with AFM.

The particle sizes of CNPPs, CN, and CNPS were determined by photo correlation spectroscopy (Nanophox) at 25°C, while the concentration of pRNA dimer was too low to detect. The measurements were performed in triplicate, and the results were reported as the mean value of 50% particle distribution.

Zeta potentials of pRNA dimers, CNPS, CN, and CNPPs were measured in triplicate with Malvern Zetasizer Nano ZS90 instrument (Malvern Instruments). CNPS, CN, and CNPPs were suitably diluted with RNase-free water before determination, and the results were all reported as the mean ± SD.