• Journal of Pharmaceutical Investigation
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• v.31 no.2
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• pp.101-106
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• 2001

Alginate-chitosan (anion-cationic polymeric complex) was prepared to control the release rate of silver sulfadiazine (AgSD). Na-alginate (2%) solution containing AgSD was gelled in $CaCl_2$ solution. The gel beads formed were immediately encapsulated with chitosan (CS). The gel matrix and membrane were then reinforced with chondroitin-6-sulfate (Ch6S). Release rate of AgSD from the gel matrix was investigated by placing alginate beads in the sac of cellulose membrane simmered in HEPES-buffer solution. The concentration of AgSD released was analyzed by UV at 264 nm. Incorporation capacity of AgSD in Ca-alginate gel was more than 90%. Alginate-Ch6S-CS could control the release rate of AgSD. The amount of AgSD release was dependent on the AgSD loading dose. Incorporation of tripolyphosphate (polyanionic crosslinker) onto the alginate-Ch6S-CS bead increased the release rate of AgSD. Collagen-coating had no influence on the AgSD release rate. Alginate-Ch6S-CS beads with a sufficiently high AgSD encapsulation were capable of controlling the release of the drug over 10 days. In summary, alginate-Ch6S-CS beads could be used as a sustained delivery for AgSD and provide local targeting with low silver toxicity and patient discomfort.

• Journal of Applied Biological Chemistry
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• v.66
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• pp.512-518
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• 2023

To address inherent weaknesses such as low mechanical strength and limited enzyme loading capacity in conventional chitosan or alginate beads, an additional step involving the exchange of anionic surfactants with hydroxide ions was employed to prepare porous chitosan hydrogel capsules for enzyme immobilization. Consequently, excellent thermal stability and long-term storage stability were confirmed. Furthermore, coating the porous chitosan hydrogel capsules with polydopamine not only improved mechanical stability but also exhibited remarkable enzyme immobilization efficiency (97.6% for M1-D0.5). Additionally, it was demonstrated that the scope of application for chitosan hydrogel beads, prepared using conventional methods, could be further expanded by introducing an additional step of polydopamine coating. The enzyme immobilization matrix developed in this study can be selectively applied to suit specific purposes and is expected to be utilized as a support for the adsorption or covalent binding of various substances.

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.818-825
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• 2012

Keratinases are exciting keratin-degrading enzymes; however, there have been relatively few studies on their immobilization. A keratinolytic protease from Chryseobacterium sp. kr6 was purified and its partial sequence determined using mass spectrometry. No significant homology to other microbial peptides in the NCBI database was observed. Certain parameters for immobilization of the purified keratinase on chitosan beads were investigated. The production of the chitosan beads was optimized using factorial design and surface response techniques. The optimum chitosan bead production for protease immobilization was a 20 g/l chitosan solution in acetic acid [1.5% (v/v)], glutaraldehyde ranging from 34 g to 56 g/l, and an activation time between 6 and 10 h. Under these conditions, above 80% of the enzyme was immobilized on the support. The behavior of the keratinase loading on the chitosan beads surface was well described using the Langmuir model. The maximum capacity of the support ($q_m$) and dissociation constant ($K_d$) were estimated as 58.8 U/g and 0.245 U/ml, respectively. The thermal stability of the immobilized enzyme was also improved around 2-fold, when compared with that of the free enzyme, after 30 min at $65^{\circ}C$. In addition, the activity of the immobilized enzyme remained at 63.4% after it was reused five times. Thus, the immobilized enzyme exhibited an improved thermal stability and remained active after several uses.

• Journal of Pharmaceutical Investigation
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• v.28 no.2
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• pp.109-113
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• 1998

This study is purposed to develop the sustained release and bioavailability of piracetam (PA). The use of alginate beads as a means to achieve sustained release of piracetam was evaluated in comparison with that of piracetam alone. In the PA-sodium alginate(SA) beads was confirmed by differential scanning calorimetry thermogram(DSC), indicating a relative shift of an endometric peak of PA to higher temperature. The changes in dissolution rates from PA-SA beads and PASA beads coated by chitosan(CHO) were significantly slower than that of intact PA. The release rate of PA-SA in the gastric fluid was markedly decreased compared with that in the intestinal fluid, suggesting that PA is mostly released in the intestinal fluid. However, the PA/SA ratio scarcely affected the release profile. The blood concentration- time curves of PA, PA-SA and PA-SA-CHO were obtained by oral administration to rats. $T_{max}$ of PA, PA-SA and PA-SA-CHO were 1, 10 and 6 hours, respectively. It was confirmed that the release of PA was prolonged by the formulation of PA-SA beads and PA-SA-CHO beads.

• Environmental Engineering Research
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• v.25 no.3
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• pp.426-438
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• 2020

In this study, cherry kernel shell pyrolytic charcoal was synthesized (CKSC) and composite beads were obtained by blending this pyrolytic charcoal with chitosan and Fe₂O₃ nanoparticles (Fe-C-CKSC). Cr(VI) adsorption from aqueous solutions by Fe-C-CKSC composite beads and CKSC adsorbents was studied comparatively. The effects of Cr(VI) initial concentration, adsorbent dosage, contact time, pH and temperature parameters on Cr(VI) adsorption were investigated. Adsorption reached an equilibrium point within 120 min for CKSC and Fe-C-CKSC adsorbents. The maximum Cr(VI) removal was obtained at the initial pH value of 1.56 for CKSC and 2.00 for Fe-C-CKSC. The optimum adsorbent dosage was found to be 5 g/L for CKSC and 3 g/L for Fe-C-CKSC. Based on the Langmuir model, the maximum adsorption capacities were calculated as 14.455 mg/g and 47.576 mg/g for CKSC and Fe-C-CKSC, respectively. Thermodynamic and kinetic studies were performed. As a result of adsorption kinetics calculations, adsorption was found to be consistent with the pseudo second order kinetic model. Characterization of the synthesized adsorbents was performed by SEM, BET, FTIR and elemental analysis. This study has shown that low cost adsorbents CKSC and Fe-C-CKSC can be used in Cr(VI) removal from aqueous solutions.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.1
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• pp.72-81
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• 2019

Objective: To determine the effect of gut pH and rumen microbial fermentation on glycerol encapsulated in alginate and alginate-chitosan polymers. Methods: Glycerol was encapsulated at 2.5%, 5%, 7.5%, or 10% (w/w) with sodium alginate (A) and alginate-chitosan (AC) polymers. Surface morphology and chemical modifications of the beads were evaluated using scanning electron microscopy and Fourier transform infrared (FTIR) spectra. Encapsulation efficiency was determined at the 5% glycerol inclusion level in two experiments. In experiment 1, 0.5 g of alginate-glycerol (AG) and alginate-chitosan glycerol (ACG) beads were incubated for 2 h at $39^{\circ}C$ in pH 2 buffer followed by 24 h in pH 8 buffer to simulate gastric and intestinal conditions, respectively. In experiment 2, 0.5 g of AG and ACG beads were incubated in pH 6 buffer at $39^{\circ}C$ for 8 h to simulate rumen conditions. All incubations were replicated four times. Free glycerol content was determined using a spectrophotometer and used to assess loading capacity and encapsulation efficiency. An in vitro experiment with mixed cultures of rumen microbes was conducted to determine effect of encapsulation on microbial fermentation. Data were analyzed according to a complete block design using the MIXED procedure of SAS (SAS Institute, Cary, NC, USA). Results: For AG and ACG, loading capacity and efficiency were 64.7%, 74.7%, 70.3%, and 78.1%, respectively. Based on the FTIR spectra and scanning electron microscopy, ACG treatment demonstrated more intense and stronger ionic bonds. At pH 6, 36.1% and 29.7% of glycerol was released from AG and ACG, respectively. At pH 2 minimal glycerol was released but pH 8 resulted in 95.7% and 93.9% of glycerol released from AG and ACG, respectively. In vitro microbial data show reduced (p<0.05) fermentation of encapsulated glycerol after 24 h of incubation. Conclusion: The AC polymer provided greater protection in acidic pH with a gradual release of intact glycerol when exposed to an alkaline pH.

• KSBB Journal
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• v.15 no.4
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• pp.352-358
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• 2000

Preparation for the simplified separation of chitosandoligosaccharides from enzymatic hydrolysate was investigated. Two different types of chitosan beads as substrate were prepared as organic-based bead by W/O emulsion method and water-based bead by alkaline treatement. The average size of organic-based bead was $200{\mu}m$, and that of water based beads were $4000{\mu}m$, $100{\mu}m$, $30{\mu}m$, in diameter respectively. Enzyme stability was maintained over 80% at PH 6 after 24 hours. The optimal condition for the production of chitosanoligosaccharides was at pH 6.0, $50^{\circ}C$ and 40U (200U/g-chitosan) According to final oligosaccharide concentration water-based bed showed the similar result with that of organic-based bead even through it had smaller surface area attacked by chitosanse than that of organic-based bead. It is probable that the structure of water-based chitosan bead was looser than that of organic-based bead so enzyme penetrated easily into the bead structure. For the oligosaccharide production versus surface area the different size of water-based beads was investigated, Maxiaml production yield was observed in the $30{\mu}m$ beads. Consequently the water-based chitosan bead was better than the organic-based bead in this reaction system.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.73-77
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• 2005

Plant-derived natural products have been and will continue to be valuable sources. Elicitors have been employed to modify cell metabolism in order to enhance the productivity of useful metabolites in plant cell/tissue cultures. In this study, several elicitors were used to improve the productivity of useful metabolites and to reduce culture time for archiving high concentration in P. ginseng hairy root cultures. The addition of chitosan, chitosan oligosaccharide and alginate oligosaccharide to the culture of P. ginseng hairy roots caused growth to be inhibited with the increase in elicitor concentration. The usage of the chitosan elicitor and D-glucosamine caused a slight decrease in hairy root growth, whereas total ginseng saponin accumulated slightly with the increase in elicitor concentration. When gel beads were added to the culture medium at the initial period, hairy root growth was enhanced. The maximum growth was 1.35 times higher than that of the control at $1\%$ (w/v). Total ginseng saponin content decreased due to the addition of alginate beads. This would result in consistent diffusion of lower levels of calcium ions during the culture period that promotes biomass growth.

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.186-193
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• 1996

Several chitosan beads were prepared by W/O emulsion and capillary extrusion methods. The surface structures were observed through SEM pictures, the surface areas were determined by BET method, the available amine contents were measured by picric acid titration method, and the results were correlated each other. The beads from W/O emulsion method were smaller in size but had higher hardness, surface area, and available amine contents than the ones from capillary extrusion method. Moreover, the surface area, available amine contents, apparent density and the hardness showed large differences according to the drying processes. As compared between the solvent dehydration and the freeze drying technique in W/O emulsion method, the former showed higher surface area, higher available amine contents and hardness than the latter. SEM pictures revealed that in case of solvent dehydration method, very small pores existed, whereas in case of freeze drying method, cell-like pores existed on the surface. The results of picric acid titration showed that the beads dried by solvent dehydration method were 10 times higher in amine contents than those from freeze drying method, and the amount of amine contents were increased as the surface area was increased. After fluorescamine was reacted with chitosan beads, the fluorescence labeled beads were observed through fluorescence microscope. The results showed that most of primary amine existed on the surface of beads and pores.

• Journal of environmental and Sanitary engineering
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• v.10 no.2
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• pp.1-12
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• 1995

Under accelerated industrial developments environment pollution comes out to be very stirious. Especially the ions of heavy metal from wastewater, even if they are minimal, accumulated in ecology circle and do finally injury to human health. The general process for removal of heavy metals include coagulation and following sedimentation, ion -exchange and active carbon adsorption and sedimentation that applicate in popular, needs the expense of coagulant the additional treatment of sludge on the general process of coagulation and sedimentation. It is also a serious problem that the second pollution caused by coagulant. However chelating adsorption that uses natural chelating high- molecular compound has not pollution problem Among chelating high- molecules, the diminishing chitin that contained in crustaceans as crawfish and crab in our country with affluent water resources are easy to get. So it is advantageous to use this ubiquitous material for removing heavy metals because we could reuse natural resource. In this research, the author tested the effectiveness of the adsorption and removal of heavy metal ions by chitin and its derivatives. Chitin and cellulose became beads and used as flocculant, in this test. The results are as follows . First, bead showed higher removal ratio than powder in the comparative test on adsorbents such as chitin, chitosan and cellulose. Secondly, in the variety test by the kinds of adsorbent and time. chitosan bead and cellulose bead that showed the highest removal ratio. One hour need to remove the ions of heavy metal. Thirdly, the results of the adsorption degree test by pH revealed high removal ratio adsorption of chitin, cellulose and chitosan bead in alkalin condition but chitosan bead in acidic condition.