Synthesis, characterization, and biological evaluation of poly(L-γ-glutamyl-glutamine)- paclitaxel nanoconjugate

Figures & data

Table 1 Characteristics of the PGA and PGG polymers and the PGG-PTX

Polymers/conjugates	PGA35ka,b	PGGb	PGG-PTXb
Dn/dc	0.176 ± 004	0.181 ± 0.001	0.173 ± 0.003
Mw (Da)	24,880 ± 170	53,180 ± 270	129,400 ± 1,200
Mw/Mn	1.69 ± 0.01	1.46 ± 0.01	1.87 ± 0.002
Mobile phase	PBS + 30%	PBS + 30%	PBS + 45%
	MeOH	MeOH	MeOH

Notes: dn/dc is how much the refractive index of a solution varies for a given increment in concentration.

a PGA35k was purchased from Sigma Chemical Co. Their certificate of analysis reported that its relative average Mw by viscosity was 35,600 Da and Mw by multiangle light scattering was 22,890 Da;

b The results reported here are based on multiangle light scattering.

Abbreviations: PGA, poly(l-glutamic acid); PGG, poly(l-γ-glutamyl-glutamine); PGG-PTX, poly(l-γ-glutamyl-glutamine)-paclitaxel nanoconjugate; Mw, molecular weight; PBS, phosphate-buffered saline; MeOH, methanol.

Figure 1 Synthesis of PGG-PTX nanoconjugate.

Abbreviations: HOBt, hydroxybenzotriazole; TFA, atrifluoroacetic acid; DMAP, 4-dimethylaminopyridine; NaHCO₃, sodium bicarbonate; PGA, poly(L-glutamic acid); PGG, poly(L-γ-glutamyl-glutamine); PGG-PTX, poly(L-γ-glutamyl-glutamine)-paclitaxel conjugate.

Figure 2 SEC-HLPC chromatograms of PGA, PGG, and PGG-PTX. The chromatograms were recorded at 228 nm. A) PGA; B) PGG; C) PGG-PTX.

Figure 3 Critical micellar concentration of PGG-PTX nanoconjugate. The DLS could not detect the particle size of PGG-PTX solution below 25 μg/mL. The critical micellular concentration was assumed to be about 25 μg/mL in saline at 25°C. The results are expressed as means ± SD (n = 3).

Abbreviation: DLS, dynamic light scattering.

Figure 4 Photographs of a solution of A) PGG-PTX (35% PTX loading) and B) PGA-PTX (32% PTX loading) in saline (0.9% NaCl). The polymer-PTX conjugates were dissolved in 0.9% NaCl at 50 mg/mL after sonication for 1 minute and allowed to stand for 20 minutes.

Figure 5 Inhibition of the growth of human lung cancer H460 cells as a function of concentration of PTX (O), PGA-PTX (■) and (▴) PGG-PTX.

Note: Vertical bars, SEM.

Figure S1 ¹H-NMR spectra of PGA-PGG, and PGG-PTX.

Figure S2 ¹H-NMR spectra of PGA, PGG, and PGG-PTX.

Figure S3 PGG and PGG-PTX chromatgrams using light scattering and refractive index detectors.

Figure S4 Red line came from light scattering detector. Blue line came from refractive index.

Figure S5 Size distribution of PGG-PTX in saline with various concentrations

Figure S6 PGG-PTX (2,000 μg/mL) in saline. Diameter = 13.7 nm; PDI = 0.404.

Figure S7 PGG-PTX (50 μg/mL) in saline. Diameter = 14.7 nm; PDI = 0.599.