Fig. 5.

Fourier transform infrared (FTIR) spectra of pure metformin, blank microparticles and metformin-loaded microparticles. Metformin characteristic peaks at 1663 cm⁻¹ and 3390 cm⁻¹ (blue spectrum) were not observed in the metformin-loaded microparticle spectrum (green spectrum), indicating encapsulation of the drug. The characteristic PLA C = O peak at 1764 cm⁻¹ (red spectrum) remained at practically the same position in the metformin-loaded microparticle spectrum (green spectrum), with the changes in its absorption indicating that metformin was successfully entrapped in the PLA microparticles