Fabrication of poly(D,L‐lactic acid) nanoparticles as delivery system for sustained release of L‐theanine

L‐theanine is present in tea as a unique, free, non‐protein amino acid. Due to various beneficial effects on brain activity, it is widely used as a nutraceutical. After consumption, it is rapidly absorbed and metabolised followed by excretion through urine. Therefore, the authors developed an L‐theanine delivery system by encapsulating into polymeric nanoparticles to release it slowly and make it available for a longer period of time. Poly(D, L‐lactic acid) nanoparticle (PLANP) was fabricated by the double emulsion method and L‐theanine was encapsulated into it (PLANP‐T). Spherical nanoparticles with a hydrodynamic diameter of 247 and 278 nm and surface charge of −14.5 and −25.7 mV for PLANP and PLANP‐T, respectively, were fabricated. The Fourier transform infrared spectroscopic data indicated encapsulation of L‐theanine into PLANP. The PLANP showed high L‐theanine encapsulation capacity (71.65%) with a sustained release character. The maximum release (66.3%) of L‐theanine was recorded in pH 7.3 at 48 h. The release kinetics followed the Higuchi model and the release mechanism was determined as super case‐II transport (erosion). This slow release will make it available to the target tissue for a longer period of time (sustain release effect) and will also avoid immediate metabolism and clearance from the circulation.Inspec keywords: nanomedicine, pH, polymers, nanofabrication, emulsions, biomedical materials, drug delivery systems, nanoparticles, Fourier transform infrared spectraOther keywords: brain activity, L‐theanine delivery system, polymeric nanoparticles, double emulsion method, spherical nanoparticles, surface charge, L‐theanine encapsulation capacity, poly(D, L‐lactic acid) nanoparticles, nonprotein amino acid, urine, hydrodynamic diameter, Fourier transform infrared spectroscopy, time 48.0 hour, voltage ‐25.7 mV, voltage ‐14.5 mV, size 278.0 nm, size 247.0 nm, target tissue, Higuchi model, pH