Proper functional modification and optimized adsorption conditions improved the DNA loading capacity of mesoporous silica nanoparticles

Packaging enough genetic materials is necessary for gene delivery, but functional modification of the carriers may affect their gene loading capacity. In this study, RGD peptide-modified mesoporous silica nanoparticles were synthesized to investigate the influences of functionalization on their DNA adsorption and desorption behaviors. Effects of the functionalization degree of the nanocarriers and the adsorption conditions including DNA concentration, pH, ionic strength and temperature were studied. The DNA adsorption of the nanocarriers were enhanced by reducing pH or adding moderate amounts of ionic salt. Compared with nonfunctional nanoparticles, nanoparticles with low degree of functionalization possessed decreased DNA adsorption capacity but increased adsorption stability. High degree of functionalization resulted in both poor adsorption capacity and stability. Systematic studies showed that the adsorption processes were spontaneous and endothermic, and could be well described by pseudo-second-order kinetic model, Langmuir and Freundlich models. In summary, the DNA loading capacity of mesoporous silica nanoparticles can be improved by proper functionalization and optimized adsorption conditions.