Slow release of copper from jellyfish-based hydrogels for soil enrichment

Nanotechnology has shown great potential to increase global food production and enhance food security. However, large-scale application of nano-enabled plant agriculture necessitates careful adjustments in design to overcome barriers associated with targeted nanomaterial delivery and their safety concerns. The research herein proposes the delivery of copper (Cu) from immobilized and non-immobilized copper oxide nanoparticles (Cu₂O), an active nanomaterial with antifungal and micro-nutrient properties. A benign and biodegradable jellyfish-based hydrogel was used as a platform during Cu₂O delivery to soils. The delivery kinetics and Cu dissolution from the nanocomposite were compared to those obtained with crosslinked ionic Cu in hydrogel, which was found to be a less controlled composite. In addition, changing environmental conditions from DI to soil extracts resulted in a decrease in the Cu dissolution rate (from 0.025 to 0.015 h⁻¹) and an increase in the overall normalized Cu release (0.27 to 0.76 mg g⁻¹). Use of hydrogels from natural sources allowed biodegradability over several months, adding nutrients (in the form of elements such as sulfur, nitrogen, and carbon) back to the environment, which ultimately minimizes nanomaterial required for a given desired nanomaterial yield and enhances the overall performance. Altogether, this work demonstrates the potential of Cu₂O embedded hydrogels as a benign composite for Cu slow-release and therefore bolsters the field of nano-enabled plant agriculture and supports its safe deployment at large scales.