Fig. 4

Displays the FTIR spectra of diclofenac, unmodified diatoms, modified diatoms, drug-loaded unmodified diatoms, and drug-loaded modified diatoms, showing diclofenac peaks for aromatic groups at 1453 and 1507 cm⁻¹ on modified diatoms. Some diclofenac bands shift due to interaction with the diatom surface