Biodegradable Microspheres as Hepatitis B Vaccine Delivery Systems

In order to investigate the immunogenicity of the controlled-release microencapsulated hepatitis B vaccine in mice,polyethylene glycol-poly-dl-lactide (PELA) microspheres with entrapped HBsAg were prepared by double emulsion W/O/W based on solvent extraction methods. BALB/c mice were immunized with the encapsulated vaccine by oral feeding or injection. Blood samples were collected at 8 th, 10 th, 14 th and 24 th weeks, respectively, and the levels of antibody response were detected by ELISA.It was found that the scanning electron microscopy showed the prepared microspheres had smooth and spherical surface, suitable for vaccine delivery. Two groups of mice orally fed with the encapsulated or conventional recombinant vaccines, respectively, there sera showed no obvious difference in the IgG levels. At 14 th week, the group injected with a single dose of encapsulated vaccine had a similar level of IgG response to the group injected with two doses of the recombination vaccine. At 24 th week, the IgG levels of the group injected with two doses of encapsulated vaccine were higher than those of the group injected with two doses of the recombination vaccine. It concludes that Controlled-release microencapsulated hepatitis B vaccine possesses the feature of slowly releasing in vivo and long times immunogenicity.

Biodegradable Microspheres with Poly(N-isopropylacrylamide) Enriched Surface: Thermo-responsibility, Biodegradation and Drug Release

Microspheres with thermo-responsible surface were fabricated by PCL-b-PEO-b-PNIPAM triblock copolymers. Thermo-responsible morphological changes of PCL-b-PEO-b-PNIPAM microspheres immersed in aqueous solution at temperatures above the LCST（e.g. 37 ℃） were observed from porous surface structure to compact surface layer. Enzymatic degradation and in vitro drug release results showed that the thermo-responsible surface layer greatly influenced the degradation of microspheres as well as the drug release behavior from microspheres. With the copolymerization of PNIPAM block into PCL-b-PEO copolymers, the drug release could be well regulated by changing temperatures and microspheres composition, which revealed the great potentials of microspheres with thermo-responsible surface for controlled drug release.

Local immunotherapy with interleukin - 2 delivered from biodegradable polymer microspheres combined with interstitial chemotherapy: a novel treatment for experimental malignant glioma.

OBJECTIVE:Local delivery of carmustine(BCNU)from biodegradablepolymers prolongs survival against experi-mental brain tumors.Moreover,paracrine administration of interleukin-2(IL-2)has been shown to elicit apotent antitumor immune response and to improve survival in animal brain tumor models.We report the use of anovel polymeric microsphere delivery vehicle to release IL-2.We demonstrate both in vitro release of cytokinefrom the microspheres and histological evidence of the inflammatory response elicited by IL-2 released from themicrospheres in the rat brain.Thees microspheres are used to deliver IL-2,and biodegradable polymer wafers