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One factor at a time ( OFAT ) variation experiments were conducted in order to determine key formulation factors ( concentration and volume of drug solution , evaporation rate and PLGA / PEO - PPO - PEO ratio ) influencing nanoparticle properties ( particle size and size distribution , encapsulation efficiency , drug content , zeta potential , drug dissolution rate , as well as protein binding capacity ) .
 Chemical: PLGA; Chemical: PEO - PPO - PEO
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: PEO - PPO - PEO