Semi interpenetrating hydrogels (semi-IPN) of bacterial cellulose (BC) and chitosan (Ch) crosslinked with genipin were prepared and characterised using Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Infrared spectra showed amide I and II absorption peaks at 1632 and 1554 cm À 1 and CÀ N stretching absorptions at 1250 and 1020 cm À 1 , respectively, for crosslinked hydrogels. The fibrous structure of BC and the porosity in the hydrogels were revealed by SEM. Swelling of hydrogels was sensitive to pH, and maximum at pH 1.0. Swelling of non-crosslinked samples decreased as the pH increased. However, with crosslinked hydrogels, swelling increased as chitosan ratio increased at low pH, as well as with increase in BC ratio at high pH. Free, bound and intermediate water types in hydrogels were revealed by DSC. The release kinetics of Quetiapine fumarate (QF), an antipsychotic drug used for the treatment of Schizophrenia was studied using UV spectrometry, followed predominantly, the Higuchi model at all pH for crosslinked hydrogels. The transport mechanism of hydrogels was a combination of non-Fickian and Super Case II. Crosslinked hydrogels showed controlled drug release behaviour. These hydrogel systems possess potential application in pharmaceutical field as all chemicals used in the development of the hydrogels are non-toxic, with BCÀ Ch 60:40 showing most promising potential.[a] J.

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Bacterial cellulose (BC) was synthesized using Gluconacetobacter xylinus (BCRC 14182). Synthesized BC was powdered and dissolved in Bis(ethylenediamine) copper (II) hydroxide (Cuen) solution to introduce the amine (NH2) group onto the BC network to yield modified BC (mBC) which was then blended with poly (vinyl alcohol) (PVA) and subsequently crosslinked with genipin (Gp). Pristine, modified and crosslinked hydrogels were studied using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and swelling behavior in water. FTIR revealed a distortion on the BC network chain via a reduction in the absorption of OH peak of mBC and the emergence of peaks at 1587 and 1560 cm-1 attributed to N-H stretching of the induced NH2 group. SEM confirmed the 3-D fibril and porous structure of BC which became distorted after modification and crosslinking. The hydrogels showed equilibrium water content of 86.5%, 67.5%, 66.7% and 33.0 % for BC, PVA, mBC-PVA and mBC-PVA-Gp, respectively. The decreased swelling in mBC-PVA-Gp indicated that genipin was able to crosslink the modified BC.

Objective: Bacterial cellulose (BC) is a biopolymer whose application has been limited due to the difficulty to introduce modifiable functional groups onto its network. The present study introduces new functional groups from chitosan (Chs) by in-situ method and further modified by crosslinking with genipin (Gp), a non-toxic agent. Methodology and Results: Bacterial cellulose-chitosan (BC-Chs) hydrogels were synthesized insitu, dried, immersed in genipin (Gp) solution to yield BC-Chs crosslinked hydrogel (BC-Chs-Gp) and characterized. The presence of amide 1 and II and crosslinking with genipin was revealed by FT-IR and SEM showed BC-Chs-Gp had a compact fibril network. Low tensile strength, less swelling ratio and moisture were exhibited by BC-Chs-Gp due to crosslinking. Hydrogels were active against E. coli and S. aureus. In vitro drug release studies of hydrogels using quetiapine fumarate followed the Higuchi model with a super case II transport mechanism and non-Fickian for BC-Chs-Gp. Conclusion and Application of findings. The present study utilized non-pathogenic bacteria, G. Xylinus and a natural resource (coconut) to obtain non-toxic and biocompatible hydrogels. BCChs hydrogels were prepared by simple and direct in-situ method by the introduction of Chs onto the growing network of BC and subsequently crosslinked using genipin by ex-situ modification method. The properties of the hydrogels in term of swelling ratio, moisture content, tensile strength, antibacterial activity, and their controlled drug release ability make them suitable for potential application in biomedicine, especially in transdermal patches as wound dressing and wound healing agents. Keywords: Bacterial cellulose; Chitosan; Genipin; Biocompatibility; mechanical properties.

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