(2) Physicochemical properties of the biopolymer
The hydrophilicity or hydrophobicity of PLGA end-groups affect hydration during the pore diffusion phase thereby influencing the rate of drug release from the polymeric matrix. PLGA composition-dependent changes to microparticle morphology may also affect encapsulated drug release profiles.
Encapsulated drug	PLGA Composition	Effect on particle size, drug loading and release profile	References
FITC-dextran	PLGA (50:50) with a carboxylic acid-end group, viz RG503H (Mr 24000-38000)	Sustained release achieved by ↑ porosity, pore size, and loading	Cai et al., 2009
	PLGA (50:50) with an ester-end group, viz RG502 (Mr 7000–17000)	Porosity and pore size had a minimal effect on release profile beyond initial release
Huperzine A	PLGA (75:25) of varying Mr, viz 15, 20, and 30 kDa	Drug loadings of 3.53, 1.03, and 0.41% respectively; inversely correlated with Mr	Fu et al., 2005; Ansari et al., 2012
Cephalexin	↑ Concentration of PLGA in the organic solvent (chloroform) from 25 to 33.3 mg/ml	Higher drug loading and larger particle size	Wasana et al., 2009