Synthesis of Lignosulfonate based Nanocarriers for the Delivery of Agrochemicals

Aims: The study's objective is to develop lignosulfonate-based nanocarriers as a UV protectant for agrochemical delivery

Place and Duration of Study: Department of Nano Science & Technology, Tamil Nadu Agricultural University, Coimbatore. The research was carried out between March 2021 and January 2022.

Methodology: We demonstrate a straightforward approach for the solvent – anti-solvent conversion of lignosulfonate macromolecules from black liquor derived from the paper pulping industry to nanocarriers. Due to the amphiphilic nature of lignin, nanoparticles are generated by self-assembly. To create lignin nanoparticles, a drop-by-drop solvent exchange approach has been used. The lignosulfonate solution was prepared using solvents such as ethanol and tetrahydrofuran, and then water was added as an antisolvent, resulting in the creation of nanoparticles by self-assembly. The hydrophobic portion of lignin creates the particle's core, while the hydrophilic hydroxyl groups form the particle's shell. The size and stability of nanoparticles were determined using dynamic light scattering, and the form and size of the systems were imaged using scanning electron microscopy. The functional groups of the nanoparticles were determined using Fourier transform infrared spectroscopy.

Results: Solvent tetrahydrofuran generated uniform and spherical lignosulfonate nanoparticles than the solvent ethanol employed in the solvent exchange procedure. When ethanol and cetyl trimethyl ammonium bromide were used as solvent and surfactant, respectively, the size of lignosulfonate nanoparticles was smaller (270±31.9nm). However, the stability of nanocarrier systems was unaffected by the solvent used, with polydispersity index values of 0.435±0.003 and 0.401±0.028 for tetrahydrofuran and ethanol solvents, respectively. The existence of a distinctive peak at 526 and 609 cm-1 in the infrared spectrum corresponding to sulfonic stretching indicated the presence of lignosulfonate in the carrier systems.

Conclusion: Lignosulfonate-based nanocarrier systems were developed using the solvent exchange method. However, the nanocarrier systems are to be validated to assess the bioefficacy of active molecules.