Water holding and release properties of bacterial cellulose obtained by in situ and ex situ modification

The biomedical applications of bacterial cellulose (BC) as a dressing material are mainly dependent on its water holding capacity (WHC) and water release rate (WRR), which in turn depend on pore size, pore volume and surface area. In the present study, the effects of structural modifications (in situ and ex situ) of BC on the WHC and WRR were investigated. The in situ modified BC was produced by the addition of various concentrations of a single sugar α-linked glucuronic acid-based oligosaccharide (SSGO) to the culture media while the ex situ modifications were carried out by preparing BC composites with chitosan (Ch) and montmorillonite (MMT). The morphological characteristics of the modified BC samples were studied with FE-SEM while their pore size, pore volume and surface area were determined through BET analysis. The results showed modifications in micro-fibril arrangements, pore size, pore volume and surface area in all BC samples compared to the control. The in situ modified BC showed denser fibril arrangement and decreasing pore size and pore volume with increasing SSGO concentration. Pore size and volume were also reduced in BC composites, probably due to the filling of pores by MMT and Ch. The variations in the WHC and WRR of BC samples were correlated to changes in various parameters after structural modifications. The WHC and WRR increased with pore volume and pore size in in situ modified BC samples. In ex situ modified BC, the WHC and WRR were dependent on the nature and arrangement of the composite materials on the surface and in the matrix of the BC sheets.