Hybrid Microspheres of Poly(Lactic Acid)/Palygorskite as Controlled Delivery Systems for Amino Acids

Introduction: Currently, the literature on amino acid delivery through microspheres is almost nonexistent. The present study was based on the development and characterization of hybrid microspheres of a polymeric matrix structured with palygorskite nanoclays. These microspheres are proposed to be used as controlled delivery systems of amino acids for agricultural applications. Methods: Hybrid microspheres of Poly(lactic acid) (PLA) and Palygorskite (Pal) were prepared via the double emulsion method with solvent evaporation. Likewise, the amino acids Glycine (Gly) and Glutamic acid (Glu) were integrated in situ during the preparation of the microspheres, all of which were characterized through Scanning Electron Microscopy (SEM), Particle Size (TP) and X-ray Diffraction (XRD); the amino acids were detected through Ultraviolet (UV) spectrophotometry. Results and Discusssion: Microspheres with spherical morphology were obtained, and as the Pal content increased, they displayed irregular surfaces with particle sizes between 101 and 152 μm. Pal in the microspheres was detected with XRD. The microspheres that trapped a greater amount of amino acids were those containing 2.5% Pal, which presented longer delivery times compared to those microspheres with only the PLA matrix. Conclusion: The mathematical modeling of the delivery kinetics demonstrated that the amino acid release depends on the diffusion mechanism through the microspheres; the study also demonstrated that the presence of nanoclays influences the diffusion speed.