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In vitro drug release profiles of pH-sensitive hydroxyethylacryl chitosan/sodium alginate hydrogels using paracetamol as a soluble model drug
(2017-06-01)
Treenate, Pitchaya
;
Monvisade, Pathavuth
The aim of this study is to investigate in vitro drug release profiles of pH-sensitive hydrogels composed of hydroxyethylacryl chitosan (HC) and sodium alginate (SA). The hydrogels were crosslinked by dipping method using different ionic crosslinkers (e.g., Ca2+, Zn2+ and Cu2+). The crosslinking reaction was confirmed by FT-IR. Swelling behavior and stability of the hydrogels in simulated digestive media were investigated. The result indicated that the combination between HC and SA could delay the degradation time of the hydrogels. Calcium crosslinking system showed higher stability than that of zinc or copper crosslinking system. In vitro drug release profiles were studied using paracetamol as a soluble model drug. The amount of paracetamol release in simulated gastric fluid (SGF) was relatively low (<20%). In simulated intestinal fluid (SIF), the burst release of paracetamol was depressed with increasing HC content and/or applying crosslinker. The HC75SA25 formulation demonstrated the linearity of drug release profile. Additionally, the amount of drug release from the 0.5 M calcium HC50SA50 hydrogel in SIF was lower than 20%. The comprehensive results of this study suggested their potential in the application of site-specific oral drug delivery in intestine and colon.
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Crosslinker Effects on Properties of Hydroxyethylacryl Chitosan/Sodium Alginate Hydrogel Films
(2017-04-01)
Treenate, Pitchaya
;
Monvisade, Pathavuth
The aim of this research is to investigate the effects of Ca2+ and Zn2+ ions on the swelling behavior, mechanical property and antibacterial activity of hydroxyethylacryl chitosan (HC)/ sodium alginate (SA) hydrogel films. The hydrogel films composed of HC and SA in different proportions (75:25, 50:50 and 25:75 w/w) were prepared by dipping method using calcium chloride as a single crosslinking agent and both calcium chloride and zinc sulfate as a couple crosslinking agent. The structures of the films were characterized by infrared spectroscopy (FT-IR). It was found that Ca2+ ions could only crosslink with SA through the formation of ionic bonds while Zn2+ ions could crosslink both HC through the formation of coordinate bonds and SA through the formation of partially ionic or coordinate bonds. The swelling behaviors of the films in phosphate buffered saline (PBS) were investigated. The results showed relatively high stability for the crosslinked films with the couple crosslinking agent. The mechanical properties of the hydrogel films were also tested. It was found that the mechanical properties of the calcium-zinc crosslinked films were greater than calcium crosslinked films. The values of tensile strength and elongation at break of the calcium-zinc crosslinked films in the fully hydrated state were up to 12.9 MPa and 67%, respectively. Additionally, the calcium-zinc crosslinked films evidenced better antibacterial activity to Staphylococcus aureus than calcium crosslinked films. Moreover, all of prepared hydrogel films exhibited no cytotoxicity for Vero cells. The comprehensive results suggest their potential as a wound dressing.
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The effect of glycerol/water and sorbitol/water on the plasticization of hydroxyethylacryl chitosan/sodium alginate films
(2015-11-04)
Treenate, Pitchaya
;
Monvisade, Pathavuth
;
Yamaguchi, Masayuki
This research aimed to investigate on the effects of glycerol/water and sorbitol/water on the plasticization of hydroxyethylacryl chitosan (HC)/sodium alginate (SA) films. The HC/SA films were prepared with different amount of glycerol or sorbitol as a plasticizer (25, 40 and 50% w/w) and kept at different relative humidity (0% RH and 50% RH) in order to restrict the content of water within the films. The results from differential scanning calorimetry (DSC) showed the miscibility of polymer and plasticizers (glycerol and sorbitol) for all blend compositions. A remarkable reduction of glass transition temperature (T<inf>g</inf>) could be obtained by adding glycerol over 40% w/w. For sorbitol plasticized films, although the addition of sorbitol could reduce T<inf>g</inf>, it was still higher than room temperature. It was claimed that glycerol could gain more effective plasticizing than sorbitol in the HC/SA films. In the cooperation with water as co-plasticizer (glycerol/water or sorbitol/water), the T<inf>g</inf> values of all films were dramatically decreased to -50 °C for glycerol/water plasticized films and down to 0 °C for sorbitol/water plasticized films. The reasonable flexible films could be obtained by the use of either glycerol/water or sorbitol/water as couple plasticizers.
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Development of hydroxyethylacryl chitosan/alginate hydrogel films for biomedical application
(2014-12-01)
Treenate, Pitchaya
;
Monvisade, Pathavuth
;
Yamaguchi, Masayuki
Novel hydrogel films composed of hydroxyethylacryl chitosan (HC) and sodium alginate (SA) were prepared for biomedical application by using calcium chloride (CaCl<inf>2</inf>) as a nontoxic ionic crosslinker to form a semi-interpenetrating polymer network (semi-IPN). HC was successfully prepared by following a Michael addition reaction of chitosan (CS) and hydroxyethylacrylate completely dissolved in distilled water at 70 °C. The distribution pattern of Ca2+ ions were well-dispersed within the hydrogel films examined by scanning electron microscope-energy dispersive spectrometry (SEM-EDS), implying uniformity of crosslinking. The swelling behavior of the hydrogel films in distilled water, simulated gastric fluid (SGF, pH = 1.2) and phosphate buffer solution (PBS, pH = 7.4) were investigated. The equilibrium swelling degree of the hydrogel films in distilled water increased with a decreas of either the SA content or the concentration of CaCl<inf>2</inf>. The hydrogel films showed pH-dependent behavior in that the shapes of the hydrogel films were stable in SGF while they degraded in PBS. The tensile strength and elongation of the hydrogel films reached 12.1 MPa and 162%, respectively, which presented reasonable mechanical properties during use and enough flexibility to follow skin movement. Cell viability of the hydrogels was measured using a methylthiazol tetrazolium (MTT) assay. The results indicated that the hydrogel films are not cytotoxic.

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