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Silica nanomaterials have been studied based on their potential applications in a variety of fields, including biomedicine and agriculture. A number of different molecules have been condensed onto silica nanoparticles’ surfaces to present the surface chemistry needed for a given application. Among those molecules, (3-aminopropyl)triethoxysilane (APS) is one of the most commonly applied silanes used for nanoparticle surface functionalization to achieve charge reversal as well as to enable cargo loading. However, the colloidal stability of APS-functionalized silica nanoparticles has not been thoroughly studied, which can be problematic when the high reactivity of amine groups is considered. In this study, four different types of silica nanoparticles with varied location of added APS have been prepared via a reverse micro emulsion process, and their colloidal stability and dissolution behavior have been investigated. Systematic characterization has been accomplished using transmission electron microscopy (TEM), silicomolybdic acid (SMA) spectrophotometric assay, nitrogen adsorption–desorption surface area measurement, and aerosol ion mobility-mass spectrometry to track the nanoparticles’ physical and chemical changes during dissolution. We find that when APS is on the interior of the silica nanoparticle, it facilitates dissolution, but when APS is condensed both on the interior and exterior, only the exterior siloxane bonds experience catalytic hydrolysis, and the interior dissolution is dramatically suppressed. The observation and analyses that silica nanoparticles show different hydrolysis behaviors dependent on the location of the functional group will be important in future design of silica nanoparticles for specific biomedical and agricultural applications. 

Projected population increases over the next 30 years have elevated the need to develop novel agricultural technologies to dramatically increase crop yield, particularly under conditions of high pathogen pressure. In this study, silica nanoparticles (NPs) with tunable dissolution rates were synthesized and applied to watermelon (Citrullus lanatus) to enhance plant growth while mitigating development of the Fusarium wilt disease caused by Fusarium oxysporum f. sp. niveum. The hydrolysis rates of the silica particles were controlled by the degree of condensation or the catalytic activity of aminosilane. The results demonstrate that the plants treated with fast dissolving NPs maintained or increased biomass whereas the particle-free plants had a 34% decrease in biomass. Further, higher silicon concentrations were measured in root parts when the plants were treated with fast dissolving NPs, indicating effective silicic acid delivery. In a follow-up field study over 2.5 months, the fast dissolving NP treatment enhanced fruit yield by 81.5% in comparison to untreated plants. These findings indicate that the colloidal behavior of designed nanoparticles can be critical to nanoparticle-plant interactions, leading to disease suppression and plant health as part of a novel strategy for nanoenabled agriculture.