A one-step electrospray-based technique for modulating morphology and surface properties of poly(lactide-co-glycolide) microparticles using Pluronics^®

Figures & data

Figure 1 Scanning electron micrographs of electrosprayed microparticles (A–D), and digital images of PLGA, PLGA-F127, PLGA-P123, and PLGA-L121 microparticles dispersions in water (E–F). (A) PLGA microparticles. (B) PLGA-Pluronic^® F127 microparticles. (C) PLGA-Pluronic^® P123 microparticles. (D) PLGA-Pluronic^® L121 microparticles. Low magnification images: scale bar 10 μm; insets (top right) are high magnification images: scale bar 1 μm; insets (bottom right) S and ZP represented as mean ± standard deviation in μm and mV, respectively. (E) Before sonication. (F) After sonication.

Abbreviations: PLGA, poly(lactide-co-glycolide); S, size; ZP, zeta potential.

Figure 2 Plot of partition coefficient (determined by Rose Bengal assay) against weight of microparticles.

Notes: Green: PLGA-F127 (R² = 0.99, P value = 0.0018); blue: PLGA-P123 (R² = 0.97, P value = 0.0136); and red: PLGA-L121 (R² = 0.99, P value = 0.0029) with corresponding linear trend lines (black dotted lines) for slope determination. For values of P < 0.05, the difference is statistically significant.

Abbreviations: PLGA, poly(lactide-co-glycolide); R², Pearson’s correlation coefficient.

Figure 3 XPS analysis of surface chemistry. (A) Chemical structure of PLGA and Pluronic^® representing its monomer units. (B) Deconvoluted C-1s XPS spectra (binding energy versus intensity) of microparticles fabricated from PLGA-F127, PLGA-P123 and PLGA-L121. (C) Graphic representing differences in EO chains lengths of Pluronic^® F127, Pluronic^® P123, and Pluronic^® L121 on the surface of electrosprayed PLGA-Pluronic^® microparticles.

Abbreviations: EO, ethylene oxide; PEO, poly(ethylene oxide); PLGA, poly(lactide-co-glycolide); PPO, poly(propylene oxide); XPS, X-ray photoelectron spectroscopy.

Table 1 Concentration in atomic percentage of various components of C-1s on surface of PLGA-Pluronic^® microparticles derived from XPS spectra along with values of monomer ratio, mass ratio, and A_s

Particle type	Concentration in atomic percentage of C-1s species
	(1)C–C 284.8 eV	(2)C–O 286.2 eV	(3)C–C–O 287.2 eV	(4)O═C–O 288.9 eV	MnR	% MsR	As
PLGA-F127	56.99	20.33	8.56	14.11	0.42	32.80	6.56
PLGA-P123	56.78	19.00	8.39	15.83	0.37	32.50	6.50
PLGA-L121	54.55	20.68	8.88	15.88	0.39	33.00	6.60

Abbreviations: As, degree of accumulation; MnR, monomer ratio; MsR, mass ratio; PLGA, poly(lactide-co-glycolide); XPS, X-ray photoelectron spectroscopy.

Table S1 Molecular weight of monomers for PLGA and Pluronic^®

Polymer	Monomer molecular weight (Mo)
PLA	72
PLGA 85:15 (Y)	69.9
PGA	58
PEO	44
PPO	58
Pluronic^®-F127 (%EO 75.51 + % PO 24.49) (X1)	47.42
Pluronic^®-P123 (%EO 36.23 + % PO 63.77) (X2)	52.93
Pluronic^®-L121 (%EO 12.82 + % PO 87.18) (X3)	56.20

Notes: Y, X1, X2, and X3 were as used in Equations S1$\text{Monomer}\hspace{0.17em}\text{ratio}\hspace{0.17em}\text{MnR}=\frac{0.5\times \%(2)\text{C}–\text{O}}{0.5\times \%(2)\text{C}–\text{O}+\%(3)\text{O}═\text{C}–\text{O}}$(S1) and S2$\%\hspace{0.17em}\text{mass}\hspace{0.17em}\text{ratio}\hspace{0.17em}\text{MsR}=\frac{0.5\times \%(2)\text{C}–\text{O}\times \text{Xi}}{0.5\%(2)\text{C}–\text{O}\times \text{Xi}+\%(3)\text{O}═\text{C}–\text{O}\times \text{Y}}$(S2) .

Abbreviations: Mo, molecular weight; PEO, poly(ethylene oxide); PGA, polyglycolic acid; PLA, polylactic acid; PLGA, poly(lactide-co-glycolide); PPO, poly(propylene oxide).