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A central composite design was applied for optimization of the formulation parameters and for studying the effects of three independent variables : PLGA concentration , polyvinyl alcohol ( PVA ) concentration and organic solvent removal rate on the particle size and the entrapment efficiency ( response variables ) .
 Chemical: PLGA; Chemical: polyvinyl alcohol; Chemical: PVA
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: PLGA; Chemical: polyvinyl alcohol; Chemical: PVA