Alginate Nanohydrogels as a Biocompatible Platform for the Controlled Release of a Hydrophilic Herbicide

Abstract

The large-scale application of volatile and highly water-soluble pesticides to guarantee crop production can often have negative impacts on the environment. The main loss pathways are vapor drift, direct volatilization, or leaching of the active substances. Consequently, the pesticide can either accumulate and/or undergo physicochemical transformations in the soil. In this scenario, we synthesized alginate nanoparticles using an inverse miniemulsion template in sunflower oil and successfully used them to encapsulate a hydrophilic herbicide, i.e., dicamba. The formulation and process conditions were adjusted to obtain a unimodal size distribution of nanohydrogels of about 20 nm. The loading of the nanoparticles with dicamba did not affect the nanohydrogel size nor the particle stability. The release of dicamba from the nanohydrogels was also tested: the alginate nanoparticles promoted the sustained and prolonged release of dicamba over ten days, demonstrating the potential of our preparation method to be employed for field application. The encapsulation of hydrophilic compounds inside our alginate nanoparticles could enable a more efficient use of pesticides, minimizing losses and thus environmental spreading. The use of biocompatible materials (alginate, sunflower oil) also guarantees the absence of toxic additives in the formulation.

Stability Phenomena Associated with the Development of Polymer-Based Nanopesticides

“…Alginate nanoparticles have been designed for pesticide, fertilizers, and herbicide release. In this context, nanosystems based on alginate exposed appropriate behavior for encapsulating hydrophilic herbicides such as dicamba [ 26 ]. The nanoformulation presented homogeneous size distribution and a release dominated by diffusion through 10 days, demonstrating the nanosystem's efficacy.…”

Translating controlled release systems from biomedicine to agriculture

“…This approach has been used to generate CRSs for delivery of a wide variety of agrochemicals, including plant regulators (Santo Pereira et al, 2017;Valderrama et al, 2020), insecticide metabolites (Namasivayam et al, 2018), herbicides (Maruyama et al, 2016;Ghaderpoori et al, 2020), and fungicides (Maluin et al, 2019). These materials provide sustained release that can extend activity of agrochemicals in the field (Artusio et al, 2021).…”

Encapsulation with Natural Polymers to Improve the Properties of Biostimulants in Agriculture

“…Encapsulation with alginate is used in some agrochemical formulations, especially to control the release of active ingredients [ 63 ], for example, to control the release of pesticides [ 64 , 65 ], herbicides [ 66 ], or fungicides [ 67 ]. Another use is the optimization of the fertilization process by encapsulating various fertilizers such as biochar [ 68 ] or biofertilizers [ 69 ].…”