Photo/thermal response of polypyrrole-modified calcium alginate/gelatin microspheres based on helix-coil structural transition and the controlled release of agrochemicals

Recent Advances in Stimulus-Responsive Nanocarriers for Pesticide Delivery

In an effort to make pesticide use safer, more efficient, and sustainable, micro-/nanocarriers are increasingly being utilized in agriculture to deliver pesticide-active agents, thereby reducing quantities and improving effectiveness. In the use of nanopesticides, the choice to further design and prepare pesticide stimulus-responsive nanocarriers based on changes in the plant growth environment (light, temperature, pH, enzymes, etc.) has received more and more attention from researchers. Based on this, this paper examines recent advancements in nanomaterials for the design of stimulus-responsive micro-/nanocarriers. It delves into the intricacies of preparation methods, material enhancements, in vivo/ex vivo controlled release, and application techniques for controlled release formulations. The aim is to provide a crucial reference for harnessing nanotechnology to pursue reduced pesticide use and increased efficiency.

A Self-Healing Thermoset Epoxy Modulated by Dynamic Boronic Ester for Powder Coating

Thermoset powder coatings exhibit distinctive characteristics such as remarkable hardness and exceptional resistance to corrosion. In contrast to conventional paints, powder coatings are environmentally friendly due to the absence of volatile organic compounds (VOCs). However, their irreversible cross-linking structures limit their chain segment mobility, preventing polymers from autonomously repairing cracks. Dynamic cross-linking networks have garnered attention for their remarkable self-healing capabilities, facilitated by rapid internal bond exchange. Herein, we introduce an innovative method for synthesizing thermoset epoxy containing boronic ester moieties which could prolong the life of the powder coating. The epoxy resin system relies on the incorporation of two curing agents: one featuring small-molecule diamines with boronic bonds and the other a modified polyurethane prepolymer. A state of equilibrium in mechanical properties was achieved via precise manipulation of the proportions of these agents, with the epoxy composite exhibiting a fracture stress of 67.95 MPa while maintaining a stable glass transition temperature (Tg) of 51.39 °C. This imparts remarkable self-healing ability to the coating surface, capable of returning to its original state even after undergoing 1000 cycles of rubbing (using 1200-grit abrasive paper). Furthermore, the introduction of carbon nanotube nanoparticles enabled non-contact sequential self-healing. Subsequently, we introduce this method into powder coatings of different materials. Therefore, this work provides a strategy to develop functional interior decoration and ensure its potential for broad-ranging applications, such as aerospace, transportation, and other fields.

Research Progress of a Pesticide Polymer-Controlled Release System Based on Polysaccharides

In recent years, with the development of the nanomaterials discipline, many new pesticide drug-carrying systems-such as pesticide nano-metal particles, nano-metal oxides, and other drug-carrying materials-had been developed and applied to pesticide formulations. Although these new drug-loading systems are relatively friendly to the environment, the direct exposure of many metal nanoparticles to the environment will inevitably lead to potential effects. In response to these problems, organic nanomaterials have been rapidly developed due to their high-quality biodegradation and biocompatibility. Most of these organic nanomaterials were mainly polysaccharide materials, such as chitosan, carboxymethyl chitosan, sodium alginate, β-cyclodextrin, cellulose, starch, guar gum, etc. Some of these materials could be used to carry inorganic materials to develop a temperature- or pH-sensitive pesticide drug delivery system. Herein, the pesticide drug-carrying system developed based on polysaccharide materials, such as chitosan, was referred to as the pesticide polymer drug-carrying system based on polysaccharide materials. This kind of drug-loading system could be used to protect the pesticide molecules from harsh environments, such as pH, light, temperature, etc., and was used to develop the function of a sustained release, targeted release of pesticides in the intestine of insects, and achieve the goal of precise application, reduction, and efficiency of pesticides. In this review, the recent progress in the field of polysaccharide-based polymer drug delivery systems for pesticides has been discussed, and suggestions for future development were proposed based on the current situation.

Removal of low-concentration tetracycline from water by a two-step process of adsorption enrichment and photocatalytic regeneration

Developing a high-performance method that can effectively control pollution caused by low concentrations of antibiotics is urgently needed. Herein, a novel three-dimensional PPy/Zn₃In₂S₆ nanoflower composites were prepared for the comprehensive treatment of low-concentration tetracycline (Tc) hydrochloride in wastewater based on the adsorption/photocatalysis of Zn₃In₂S₆ and the conductivity of PPy. In this preparation method, adsorption enrichment and photocatalytic regeneration were conducted in two steps, eliminating the dilution and dispersion effects of aqueous solvents on photocatalytic species and antibiotics. Results showed that Zn₃In₂S₆ could effectively adsorb 87.85% of Tc at pH of 4.5 and photocatalytically degrade Tc at pH of 10.5. Although the adsorption capacity of Zn₃In₂S₆ was slightly reduced after being combined with PPy, its photocatalytic efficiency was substantially enhanced. Specifically, 0.5%PPy/Zn₃In₂S₆ could degrade 99.92% of the surface-enriched Tc in 1 h and induce the regeneration of the adsorption sites. Furthermore, the adsorption capacity remained above 85% even after recycling PPy/Zn₃In₂S₆ ten times. The photocatalytic degradation mechanism analysis revealed that the enrichment of Tc on 0.5%PPy/Zn₃In₂S₆ negatively impacts the photocatalytic efficiency, while •O₂^- and •OH radicals were the main oxidative species that played an important role in the photoregeneration process.

Novel fabrication of a yeast biochar-based photothermal-responsive platform for controlled imidacloprid release

For improving the utilization efficiency of pesticides, we developed a novel pesticide delivery particle (YINCP@EC) with a core–shell structure based on yeast biochar, imidacloprid (IMI), ammonium bicarbonate (NH₄HCO₃), calcium alginate (CA), and ethyl cellulose (EC). Therein, yeast biochar, IMI and NH₄HCO₃ were absorbed in the network-structured of CA to obtain YINCP through hydrogen bonds. The resulting composite was granulated using an ion gelation technique and then coated with EC to form YINCP@EC. In this platform, yeast biochar serving as a photothermal agent can efficiently convert sunlight energy into thermal energy, thereby triggering NH₄HCO₃ decomposition into CO₂ and NH₃ that can break through the EC coating and facilitate IMI release. In addition, the influence of yeast biochar content, pH, and coexisting ions was systematically studied to evaluate the release behavior of IMI from YINCP@EC. Moreover, the hydrophobic EC shell endowed YINCP@EC with high stability in aqueous solution for at least 60 days. Consequently, this novel composite with simple preparation, low cost and remarkable photothermal-responsive properties has a huge application potential in agriculture.

The yeast biochar-based platform exhibited excellent photothermal conversion capability, and realized light-triggered controlled release of IMI.