Alginate microcapsules

Sakai, S., Ono, T., Ijima, H. and Kawakami, K. (2001) Synthesis and transport characterization of alginate/ aminopropylsilicate/alginate microcapsule application to bioartificial pancreas. Biomaterials, 22, 2827-2834. 

Awrey, D.E. Tse, M. Hortelano, G. Chang, P.L. Permeability of alginate microcapsules to secretory recombinant gene-products. Biotech. Bioeng. 1996, 52 (4), 472 84. 

Live rotavirus vaccine was developed for oral delivery to prevent infections by the virus in young children. However, incorporation of live rotavirus into poly (oL-lactide-co-glycolide) microspheres or alginate microcapsules was reported to result in a significant loss of rotavirus infectivity. The loss was reduced by stabilization of the rotavirus vaccine with an excipient blend of cellulose, starch, sucrose, and gelatin at a mass ratio of 30 30 30 10 in granules or tablets. ... 

It has been shown that a modified drug release can be obtained from calcium alginate microcapsules, pellets, and microspheres. When biodegradable bone implants composed of calcium alginate spheres and containing gentamicin were introduced into the femur of rats, effective drug levels in bone and soft tissue were obtained for 30 days and 7 days, respectively. ... 

Chandy, T., Mooradian, D. L. and Rao, G. H., Chitosan/polyethylene glycol-alginate microcapsules for oral delivery of hirudin, /. Appl. Polym. Sci., 70,2143, 1998. 

Wen-tao, Q., Wei-ting, Y., Yu-bing, X., Xiaojun, M., 2005. Optimization of Saccaromyces cerevisiae culture in alginate-chitosan-alginate microcapsule. Biochemical Engineering Journal 25 (2), 151-157. 

Vandenberg, G. W. and None, J. D. L. Evaluation of protein release from chitosan-alginate microcapsules produced using external or internal gelation. J. Microencapsul. 18 (2001) 433-441. 

P. Ren, X. Ju, R. Xie, and L. Chu, Monodisperse alginate microcapsules with oil core generated from a microfluidic device. Journal of Colloid and Interface Science, 343, 392-395, 2010. 

Okhamafe, A.O. Amsden, B. Chu, W Goosen, M.F.A. Modulation of protein release from chitosan-alginate microcapsules modified with the pH sensitive polymer-hydroxylpropyl methylcellulose acetate succinate (HPMCAS). J. Microencapsul. 1996, 13 (5), 497-508. 

Survivability of Microencapsulated L. plantarum ATCC 8014 in Chitosan-Coated Alginate Microcapsules during Exposure... 

The survivability evaluation of microencapsulated Lactobacillus plantarum ATCC 8014 in 1%, 1.5%, and 2% of alginate and chitosan-coated alginate microcapsules along the gastro-intestinal tract will be a step forward in understanding the microencapsulation efficiency, offering an effective way for increasing the life span. 

The results are in agreement with those of Kim et al., who reported that the pH 1.2, for the non-encapsulated strain of Lactobacillus acidophilus, leads to complete death after 1 h of incubation, while encapsulated strains maintained above 10 cfu/mL after 2 h. Additionally, Mokarram et al. reported that at pH 1.5 after 2 h of incubation, the strains of L. acidophilus and Lactobacillus rhamnosus built with alginate maintained above 10 -10 cfu/mL. Chandramouli et al. reported a higher survival of Lactobacillus ssp. immobilized in alginate microcapsules in low pH environments. 

Figure 33.2 represents the dynamics of bacterial cell density and viability (expressed as log x cfu/mL) at different time intervals (30, 60, 90, and 120 min) after successive incubation of alginate microcapsules containing L. plantarum ATCC 8014 in simulated gastric juice (pH 1.5) for 60 min and in simulated intestinal juice at 37°C for 2 h. 

Many research studies were carried out in order to investigate the potentiality of chitosan-coated alginate microcapsules system to increase the survival and stability of entrapped live probiotic cells. " " ... 

In the probiotic microencapsulation research, the incorporation in alginate microcapsules and different coatings application is frequently used. Besides the additional protection that the coatings can offer to the entrapped bacteria, they could provide greater control over bacterial release. 

Several studies report the effect of chitosan coating on the viability of probiotics in simulated gastric juice, describing different results. The viability of free cells and immobilized L. plantarum ATCC 8014 in chitosan-coated alginate microcapsules during exposure to simulated gastric juice was evaluated and the results are shown in Figure 33.3. 

Chitosan-coated alginate microcapsules were the most effective in protecting probiotic bacteria from bile salt. The chitosan coating provides protection in bile salt solution because an ion exchange reaction takes place when the beads absorb bile salt." Krasaekoopt et al. found that microencapsulation with alginate coated with chitosan was the best treatment to protect L. plantarum ATCC 8014. 

On the other hand, literature studies report that the survivability and stability of probiotic bacteria loaded into chitosan-coated alginate microcapsules are largely dependent on the molecular weight of chitosan. ° Thus, the microcapsules prepared with high molecular weight chitosan provided a higher survival rate (46%) compared with the microcapsules made with low molecular weight chitosan (36%). ... 

OTHER COAT MATERIALS FOR ALGINATE MICROCAPSULES 33.7.1 POLYLYSINE-COATED AlCINATE MiCROCAPSULES... 

The literature reports show an improvement in survival and stability of microencapsulated probiotic bacteria during exposure to harsh acid conditions when polylysine has been used as a coating material. Several studies reported on alginate-polylysine microencapsulation systems coupled with bifidobacteria to investigate their survival in vitro and in vivo after oral administration. After 16 weeks of storage at 4°C, the stability of polylysine-coated alginate microcapsules successfully maintained the survival of bifidobacteria at over lO cfu/g. ... 

The study reported by Lin et al. used alginate microcapsules coated with poly-L-lysine followed by a further coating with an alginate layer. It was found that this kind of capsules does not increase the number of Escherichia coli strain during exposure to gastric juice. The strain used had high tolerance to acid and decreases over 120 min at pH 2 to 1 log/mL. 

One of the most promising formulations for an efficient microencapsulation of probiotic bacteria system is alginate-polylysine-alginate microcapsules. This kind of microcapsules has been... 

Besides this, other coating materials have also been used. The whey protein has been used to coat wet alginate microcapsules containing L. plantarum. After 90 min of exposure to simulated gastric juice, an improved survival rate of 6 log x cfu/mL was registered. The suggested rationale for this is that whey protein provides a layer around the microcapsules, which cannot be degraded by... 

The cellulose acetate phthalate, xanthan gum, starch, and gelatin" were incorporated into alginate microcapsules, showing potential for improvement of probiotic survival during their passage through the gastrointestinal tract. 

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