Microphase Separation and Gelation of Methylcellulose in the Presence of Gallic Acid and NaCl as an In Situ Gel-Forming Drug Delivery System

Novel hydrogels of methylcellulose (MC) with gallic acid (GA) and NaCl were developed for an in situ gel-forming delivery system. Plain MC and GA/NaCl/MC were characterized using micro-differential scanning calorimetry (micro-DSC), rheological and turbidity methods. The gelation temperatures of MC were reduced to body temperature with adding GA/NaCl. GA and NaCl caused slightly different effects on the gelation/degelation temperatures during heating/cooling, respectively, based on the different sensitivities of these three techniques. The gelation mechanism was investigated by UV spectrophotometry, and the hydrophobic interaction between the aromatic ring of GA and MC was verified. The NaCl/MC hydrogel had smaller micropores than GA/MC and MC, indicating a greater crosslinked density. Doxycycline (DX) was loaded into the systems and demonstrated a synergistic effect of DX/GA. Both GA and DX exhibited a sustained release. The hydrogel of GA/4NaCl/MC could be potentially used for the in situ delivery of DX for deep wound healing.