Study Of Chitosan, Agarose Extraction And Their Application To Control-release Phycobiliproteins

Cancer becomes to be the first threaten to the health of people these years. The traditional therapeutic methods including radiation therapy, chemical therapy and operation therapy can all bring a lot of suffering to the patients. Photodynamic therapy (PDT) is a new endoscopic treatment of cancers based on the photosensitization of neoplasms following the administration of a photosensitizer prior to laser light-induced tissue destruction. It requires both light and light sensitive agents (also called photosensitizers) and acts in an oxygen-rich environment; that is to say, this therapy involves the appropriate photosensitizer and irradiation with light of a particular wavelength, thereby initiating tumor necrosis presumably through formation of singlet oxygen.The core of PDT is to find a suitable photosensitizer. Phycobiliproteins are water-soluble and its apoproteins carry two different, covalently bound tetrapyrrole prosthetic groups: phycoerythrobilin and phycourobilin. Recent studies show that phycobiliproteins may be used as photosensitizers in tumor photodynamic therapy. As phycobiliprotein is a kind of protein, it is easily to be degraded by the enzymes in the body. Thus, the problem to be faced at present is the development of suitable protein delivery devices.Control-release is a technique or method by which active chemicals are made available to a specified target at a rate and duration to accomplish an intended effect. Therefore, the technology of drug controlled-release offers the effective way to medicate phycobiliproteins.In this study, the chitin was extracted from the exoskeleton of the prawn. The influences of alkali treatment and temperature on the deacelation process of chitin were discussed. The results showed that the addition of ethanol and raising temperature could increase the deacelation degree of chitin; the deacelation reaction with the lying of the ethanol was a first order reaction; the intermission alkali treatment can obtain chitosan of high deacelation degree with high molecule weight. Agar is a polysaccharide complex extracted from the agarophyte members of Rhodophyta. Several experimental methods for agar extraction from Gracilaria lemaneiformis were studied in this paper. The effects of alkali, microwave, ultrasonic treatment on the agar yield, sulfate content and polysaccharide content were investigated. The results obtained showed that the alkali treatment could decrease the agar yield as well as the sulfate content and the agar yield, the sulfate content were negatively affected by the increase of the NaOH concentration; on the contrary, the microwave and ultrasonic treatment could increase the agar yield, as well as the sulfate content, and the agar yield and the sulfate content were increased with the increasing of microwave and ultrasonic treatment time. Moreover, the states of the alga before and after alkali treatment were observed in microscopical and macroscopical conditions.The agar was extracted from Gracilaria Lemaneiformis with hot water and was then purified by DE-22 and Sephadex G-200 column chromatograph. The purified agarose contained little sulfate. Its homogeneity was identified with Q-Sepharose column chromatography. The ultraviolet spectrum showed that there was no protein and nucleic acids in the purified polysaccharide. The infrared spectrum indicated that there were special absorption of 3,6-anhydro-galactose and very little sulfate absorbance peaks. There were two weight loss processes during the increasing temperature from 0 to 700℃, and there was a transition from double helix structure to random coil with the increasing temperature in the polysaccharide solution.Phycobiliproteins were isolated and purified from alga Polysiphonia urceolata Grev and Spirulina Platensi using Streamline column combined with ion-exchange chromatography or hydroxyapatite chromatography. The purified phycobiliproteins were identified with absorbance spectra and electrophoresis.In this article, a hydrophilic natural polymer, chitosan and agarose were used to form gel-microspheres, macroporous microspheres and magnetic microspheres by suspension cross-linking method. These microspheres were used to load phycobiliproteins by adsorption method. The R-PE loading efficiency was highest when pH value was 3.59 (close to its isoelectric point). When R-PE concentration was below 1.25 mg/ml, the loading efficiency increased with enhancing of R-PE concentration. In addition, the R-PE loading efficiency was enhanced with the increasing temperature, and little influenced by the ion strength. The presence of agarose in the microspheres can somewhat slow down the loading capacity and accelerate the release rate of R-PE. Changing R-PE concentration and adding agarose to the chitosan microspheres can adjust the release rate of R-PE someway.The particle size, crosslinking degree, adsorption and release,deacelation degree of chitosan, and the porous of microspheres were all the factors that could effect the adsorption and release ability of C-PC. Reduce the particle size, pull down the crosslinking degree, increase the deacelation degree of chitosan and turn the gel-microspheres to porous microspheres were profitable to the adsorption, and reduce the particle size, pull down the crosslinking degree, reduce the deacelation degree of chitosan and turn the gel-microspheres to porous microspheres were profitable to the C-PC release.