Formulation and characterization of polysaccharide beads for controlled release of plant growth regulators

Owing to their chemical, physical, and functional characteristics, polysaccharides are considered to be the most versatile natural polymers. As a result, their properties have been exploited in various fields of research in the biomedical, pharmaceutical, cosmetic, food, and agricultural industries. A property of special interest is their ability to form systems or materials with unique physicochemical characteristics, such as hydrogels and micro- and nanoparticles for controlled release of active compounds. In the present study, polysaccharide beads formulated from alginate, cellulose powder, cellulose nanocrystals, starch, and xylan were reinforced with kaolin and surface-modified with polyethylenimine (PEI), a positively charged polyelectrolyte. Addition of kaolin improved the mechanical strength of the beads. Modification of the surface of the beads with PEI facilitated better control of the release rate of the plant growth regulator, phenylacetic acid (PAA). The physical properties of the beads were characterized by optical and scanning electron microscopy, and their mechanical strength was determined by an Instron 5565 Tensile Testing Machine. Cumulative release of PAA was measured by UV–Vis spectroscopy.