PEG-PLGA

In the next series of studies, Jeong et al. found compositions of HPL/HPB balanced triblock copolymers, PEG-PLGA-PEG, that exhibit sol-to-gel (lower transition) and gel-to-sol (upper transition) transitions as temperature mono-tonically increases (27). The lower transition is important for drug delivery application because the solution both flows freely at room temperature and becomes a gel at body... 

Figure 1 Phase diagram for PLGA-PEG-PLGA in aqueous solution (ReGel ). (From Refs. 6.)...

Figure 3 Physical crosslinks in the PLGA-PEG-PLGA in water (ReGel ) showing hydrophobic domain structures (Courtesy of Macromed, Inc., Sandy, UT.)...

Microspheres of the biodegradable, triblock copol3rmer (PLGA-PEG-PLGA, Mw = 4000, 1500-1000-1500 by NMR) were prepared in two methods microsphere A (Msp A aqueous-based) and microsphere B (Msp B dichloromethane). For both microspheres, an equal amoxmt of Zn-insiilin was loaded ( 4% of pol3nner mass). In vitro release studies were carried out with both. As shown in Fig. 6, Msp A exhibited a continuous and nearly complete release of insiilin over 3 weeks. The first phase of insulin release (the first 10 days) from Msp A seems to be dependent more upon diffusion, indicated by the slight decrease in the release rate over time. Then, after day 10, the insulin release rate turned to an... 

Jeong B, Bae YH, Kim SW. In situ gelation of PEG-PLGA-PEG triblock copolymer aqueous solutions and degradation thereof. J Biomed Mater Res 2000 50 171-177. 

Choi S, Baudys M, Kim SW. Control of blood glucose by Novel GLP-1 delivery using biodegradable triblock copolymer of PLGA-PEG-PLGA in type 2 diabetic rats. Pharm Res 2004 21 827-831. 

Figure 4 Phase diagram of PEG-PLGA-PEG (550-2810-550) triblock copolymer aqueous solution. Cross bar temperature where the formed gels become turbid. (From Ref. 50.)...

Qiao M, Chen D, Ma X, Liu Y. Injectable biodegradable temperature-responsive PLGA PEG-PLGA copolymers Synthesis and effect of copolymer composition on the drug release from the copolymer-based hydrogels. Int J Pharm 2005 294 103 112. 

Temperature-sensitive PLGA-PEG-PLGA Insulin Antidiabetes [91]... 

Temperature-sensitive PEG-PLGA-PEG Plasmid DMA Gene delivery [93]... 

Jeong, B., Bae, Y.H. and Kim, S.W., 2000. Drug release from biodegradable injectable thermosensitive hydrogel of PEG-PLGA-PEG triblock copolymers. Journal of Controlled Release, 63, 155-163. 

PLLA-PEO-PLLA PCL-PEG-PCL PLGA-PEG-PLGA M MA, AgCA, PPF, m-PEG Tissue fillers... 

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