In situ mucoadhesive hydrogel based on methylcellulose/xyloglucan for periodontitis : graphical abstract

Novel hydrogels of 5, 6, and 7% w/v of methylcellulose (5MC, 6MC, and 7MC) with 1.5% w/v of tamarind seed xyloglucan (TSX) were developed via an in situ gel forming process. The MC and MC/TSX solutions formed two gel types: a soft gel and a turbid hard gel respectively upon heating. These samples were characterized using a test-tube-tilting method (TTM), rheological, and turbidity measurements. The interactions and the mechanism of gelation were studied using ATR-FTIR. The release of metronidazole (MTZ) from the hydrogels was also investigated. Based on the TTM results, 6MC/TSX, 7MC, and 7MC/TSX were solution at room temperature but could form gel at body temperature. ATR-FTIR demonstrated stronger hydrophobic associations of MC in the turbid gel than in the soft gel which corresponded to the higher intensity of the C–O band of MC. The peak intensity was greater in the presence of TSX, reflecting the role of TSX to increase hydrophobicity and decrease gelation temperature of MC. SEM revealed a microporous morphology of 6MC/TSX, 7MC, and 7MC/TSX and the pore size of the soft gel was greater than that of the turbid gel. The high relative rheological synergism at 37 °C indicated a high mucoadhesive property of the MC/TSX hydrogels. MC and MC/TSX exhibited a suitable syringeability to ease of administration at 25 °C. MTZ exhibited a more sustained release from 7MC/TSX than from a commercial formulation. Therefore, 7MC/TSX hydrogel could be potentially used for the in situ delivery of MTZ for the treatment of periodontitis