Synthesis Characterization and In Vitro Release Kinetics of L-Serine From PVP Microparticles

Abstract

Owing to the significant physical and chemical properties and the usage in numerous fields, nanoparticles/microparticles synthesis is becoming important in the present scenario. L-Serine, a non-essential amino acid, plays an effective role in regulating insulin sensitivity, is used for the treatment of skin inflammation, and is an important ingredient of beauty products specifically for skin and hair. Polyvinylpyrrolidone (PVP) is widely used in food, medicine, and cosmetics, showing pharmaceutical and biomedical applications. PVP served as the polymeric matrix for the synthesis of microparticles containing L-serine and provides structural integrity and modulate release kinetics through diffusion and polymer relaxation mechanisms. With this view, in the present studies, PVP microparticles containing l-serine have been synthesized and characterized by FTIR, XRD, and EDS SEM data. Release data of L-serine from PVP microparticles were fitted using a zero-order, Higuchi and Korsmeyer–Peppas model and kinetic constants for each model were calculated. The theoretical zero-order rate constant is found to be 0.305 mg/min, which matches with its graphical value of 0.311 mg/min. Release kinetics of L-serine from PVP microparticles does not follow normal Higuchi's criteria for drug release up to 60% but with a polynomial of order 2 trend-line is obtained. For Korsmeyer–Peppas model, the value of K and n is found to be 1 and 0.9, respectively, with regression coefficient of 0.99. Result indicates that the system follows zero-order kinetics as well as Korsmeyer–Peppas model with n values of about 0.9 indicating the super-case II transport mechanism suggesting that the release is not controlled by diffusion alone; instead, polymer relaxation dominates the release process which often results in constant release rate over time. Such release profile is considered ideal for sustained release formulations, reducing side effects, and improving patient compliance. It was observed that release of l-serine from PVP microparticles exhibit 65% release within 120 min, which is substantial in release kinetics. On the basis of FTIR analysis, an attempt was made to propose the structure highlighting the interaction of L-serine encapsulated in PVP microparticles using free online Avogadro's software.