Basic Amino Acid-Modified Lignin-Based Biomass Adjuvants: Synthesis, Emulsifying Activity, Ultraviolet Protection, and Controlled Release of Avermectin

Abstract

Avermectin (AVM) is a highly effective and safe biopesticide but is very sensitive to ultraviolet (UV) light and exhibits poor water solubility. Developing green and multifunctional adjuvants is important for the protection and controlled release of AVM. In this work, a number of water-soluble enzymatic hydrolysis lignins (W-EHLs) were prepared via grafting basic amino acids and used as emulsifiers with co-surfactants to prepare high-internal phase emulsions (HIPEs). The results showed that W-EHLs with co-surfactants could be prepared with HIPEs that contained 90 vol % green oil phases such as turpentine, and the stability of the HIPEs first increased and then decreased when the rate of grafting of basic amino acids on lignin increased from 0.26 to 1.46 mmol/g. The more polar oil droplets were less deformable due to their higher viscosity, thereby affording a stability advantage to HIPEs. Subsequently, the relations between the stability and interfacial viscoelasticity of the emulsion were effectively correlated by interfacial rheology, droplet size, and physical stability tests. The results showed that HIPEs with smaller droplets had poor fluidity and strong interfacial viscoelasticity due to their higher droplet packing density, which resulted in good macroscopic stability. Like the AVM carrier, the retention rate of AVM in HIPEs was 80.1% after UV radiation for 72 h, which represented the highest UV protection efficiency in AVM delivery systems. The release curves showed that the rate of release of AVM from HIPEs was adjusted by controlling the pH value of the medium. In addition, the release of HIPEs is completely in accord with both diffusion and the matrix erosion mechanism. The strategy could be extended to other sensitive pesticides and used to promote the development of sustainable agriculture.

Chemical Transformation of Lignosulfonates to Lignosulfonamides with Improved Thermal Characteristics

“…Although unmodified lignin displays many attractive features, such as biodegradability, good thermal stability, antioxidant properties, and the ability to absorb UV-rays [17,18], applying chemical modification procedures allow for obtaining lignin-based materials with enhanced properties via utilization of various types of reactions, such as esterification [19], etherification [20,21], epoxidation [22], and amination [23], to name a few [24]. Other methods to obtain value-added chemicals employ depolymerization of lignin to simple molecules and then their use as building blocks in the synthesis of the new functional materials [25].…”

High-value utilization of lignin: construction of an intelligent release system for targeting the delivery of pesticides

“…68 The release of AIs in emulsion systems is closely related to the stability of the emulsion, which is regulated by the content and amphiphilicity of lignin particles. 59,60 Insufficient lignin at the oil-water interface hinders the formation of a stable emulsion, while an excessive content leads to aggregation and affects the emulsification performance. Lignin particles with excessive hydrophilicity or lipophilicity fail to stabilize well at the oil-water interface, requiring modification to achieve suitable amphiphilicity.…”

“…Generally, higher stability of the emulsion results in a slower release of AIs. 59,60 Lignin-based coacervates…”

“…3c). 78,79 Chen et al 60 developed a lignin-based emulsion for encapsulating avermectin (AVM), where the release of AVM under neutral conditions was relatively low (Fig. 3d).…”

Harnessing Nanovaccines for Effective Immunization─A Special Concern on COVID-19: Facts, Fidelity, and Future Prospective

“…35 In addition, some adjuvants are light-sensitive, can degrade when exposed to UV light, and need storage in dark or light-protected containers to retain stability. 36 Adjuvants should be stored separately or in a way that minimizes contact with other vaccine components until they are ready to be used. Specific vaccination components and some adjuvants may interact, resulting in diminished efficacy or unfavorable reactions.…”