Sulfonate-Functionalized Mesoporous Silica Nanoparticles as Carriers for Controlled Herbicide Diquat Dibromide Release through Electrostatic Interaction

Abstract

Environmental stimuli-responsive pesticide release is desirable for enhanced efficiency and reduced side effects. In most cases, the loading and release of pesticides mainly depends on hydrophobic interactions and hydrogen bonding. Electrostatic interaction is less investigated as a weapon for achieving high loading content and controlled pesticide release. In this work, negative-charge decorated mesoporous silica nanoparticles (MSNs) were facilely fabricated by introducing sulfonate groups onto MSNs through a post-grafting method. Sulfonate-functionalized MSNs (MSN-SO3) were synthesized by conversion of epoxy group into sulfonate group using a bisulfite ion as a ring opening reagent. Diquat dibromide (DQ), one of the globally used quaternary ammonium herbicides, was efficiently loaded into these negatively charged MSN-SO3 nanoparticles. The loading content was increased to 12.73% compared to those using bare MSNs as carriers (5.31%). The release of DQ from DQ@MSN-SO3 nanoparticles was pH and ionic strength responsive, which was chiefly governed by the electrostatic interactions. Moreover, DQ@MSN-SO3 nanoparticles exhibited good herbicidal activity for the control of Datura stramonium L., and the bioactivity was affected by the ionic strength of the release medium. The strategy of cargo loading and release dependent on the electrostatic interactions could be generally used for charge-carrying pesticides using carriers possessing opposite charges to mitigate the potential negative impacts on the environment.

High Surface Area Mesoporous Silica Nanoparticles with Tunable Size in the Sub-Micrometer Regime: Insights on the Size and Porosity Control Mechanisms

“…When NaOH is used to catalyze the synthesis of MSN, typically a high reaction temperature (80–100 °C) and a large volume of aqueous base (200–1000 mL) are required [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ] to contain MSN size in sub-micrometer regime [ 49 ]. In fact, such a temperature range, required to trigger nucleation and MSN formation, results in the formation of large, micrometer-sized, silica particles aggregates, and the use of large volume of aqueous NaOH limits particle aggregation and uncontrolled formation of larger MSNs thanks to dilution.…”

Porous Silica Nanocarriers: Advances in Structural Orientation and Modification to Develop Sustainable Pesticide Delivery Systems

“…66 Though this process is easy, it requires long time periods and sometimes satisfactory loading content cannot be achieved due to the small pore sizes. 67,68 To this end, large-pore mesoporous silica can be a viable option to ensure a high amount of AI loading. 69 Along with pore size, pore channel structures of MSNs also influence the loading efficiency.…”

Nanomaterials and nanotechnology for the delivery of agrochemicals: strategies towards sustainable agriculture

“…The release of DQ from DQ@MSN-SO 3 nanoparticles was dependent on pH and ionic strength, which were mainly determined by electrostatic interactions. Bioactivity studies showed that DQ@MSN-SO 3 nanoparticles exhibited good herbicidal activity in controlling Datura stramonium L. compared to the control [ 42 ]. Xiang et al obtained a pH-reacting controlled-release formulation using attapulgite-based hydrogel.…”