Electronic Supplementary Information
The preparation and characterization of micelles from poly (γglutamic acid)-graft-poly (L-lactide) and the cellular uptake thereof
Meiqing Liua, Gang Huangb, Yingying Conga, Guoquan Tongb, Zhanqiu Linb, Yihua
Yina*, Chao Zhangb*
a
School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University
of Technology, Wuhan, Hubei 430070, China
b
School of Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510006,
China
*
Corresponding authors:
Professor Yihua Yin, Tel: +86-027-87859019; E-mail: yihuayin@aliyun.com;
Associate Professor Chao Zhang, Tel: +86-020-3933-2145; Email:
zhchao9@mail.sysu.edu.cn.
Microwave-assisted hydrolysis of γ-PGA
In a typical reaction, high-molecular-weight γ-PGA (Mw=1×106 g/mol) was dissolved
in dilute hydrochloric acid and subjected to microwave irradiation in a MAS-II
microwave chemical reactor (Sineo, Shanghai, China). After the reaction, the reaction
mixture was neutralized by saturated NaHCO3 solution before dialysis (MWCO of
14kDa) against pure water for 72 h and lyophilized. By controlling the pH value of
solution, the microwave time and temperature, different molecular weight γ-PGA
were acquired.
Table S1. Conditions for the microwave-assisted hydrolysis
Sample
PGAI
PGAII
pH
1
2
Time(min)
90
60
Temperature(oC)
90
70
Determination of the molecular weight of γ-PGA
Number-average molar mass (Mn) of γ-PGA was determined spectrophotometrically
based on FDNB method [1]. DNP-Glu was first synthesized before set up the standard
curve, 0.2945 g glutamic acid (2 mmol) was dissolved in 10 mL of 0.1 M borate
buffer (pH 8.5). And the solution was centrifuged at 12,000 rpm for 10 min at 25 oC,
the supernatant was mixed with 10 mL of 10 mM FDNB solution in acetone and
incubated at 65 oC for 45 min in the dark. Then the solution was incubated in 3.3 M
HCl with pH 1-2 at 105 oC for 12 h, crude DNP-Glu was thus synthesized and
dissolved in ethyl acetate to remove the impurities, then the ethyl acetate was
removed from the solution by evaporation using a rotavapor, the residue was washed
with water and lyophilized to acquire pure DNP-Glu.
Before measurement of Mn, the fractioned γ-PGA was reacted with FDNB following
the same procedure as that of glutamic acid, the Mn of the fractioned γ-PGA was
determined through measuring the absorbance at 356 nm on a Beckmann DU700 UVVis spectrophotometer (Beckmann-Coulter, USA).
The molar masses of PLLA-NH2 or γ-PGA were characterized via viscometric, FDNB,
or GPC method (Table 1).
Table S2. Molar masses of the γ-PGA and PLLA-NH2
Entry
PGAII
PGAI
PLLAI
PLLAII
PLLAIII
a
Average molar mass (×104g/mol)
FDNBa
Viscometryb
7.0
11.0
0.3
2.0
1
H-NMRc
GPCd
1.5
1.5
1.0
1.2
0.5
Determined spectrophotometrically using the FDNB method;
viscometer; c Determined by 1H-NMR; d Estimated using GPC.
0.8
b
Determined using
The stability study of DOX-loaded γ-PGAI-g-PLLAI micelles
1 mg of DOX∙HCl was dissolved in 1 mL of DMF, and then 10 μL of triethylamine
(TEA) was added to the solution and mixed for 6 h to produce DOX. Subsequently,
10 mg of γ-PGAI-g-PLLAI in 1 mL of DMF was mixed with the above DOX solution.
The mixture was immediately added dropwise into 8 mL of DI water under sonication
during four minutes. Then the solution was transferred into a dialysis tube (MWCO of
3500 Da) and dialyzed against pure water for 72 h. The particle size and the size
distribution were measured using the DLS during a time span of 6 days.
Figure S1. The stability of DOX-loaded γ-PGAI-g-PLLAI micelle
The synthesis of mPEG-PLGA
mPEG-PLGA was synthesized via mPEG initiated ring-opening polymerization (ROP)
of L-lactide (LA) and glycolide (GA) in bulk using Sn(Oct)2 as a catalyst. The molar
feed ratio of LA/GA was three. The ROP was carried out at 120 oC for 48 h, the
resulting product was dissolved in dichloromethane and precipitated in excessive
diethyl ether, and the precipitate was dried under vacuum overnight to obtain mPEGPLGA. The 1H-NMR spectrum was shown in Figure 2S. And the molecular weight of
the obtained mPEG-PLGA was 2.2×104 by 1H-NMR.
Figure S2. 1H-NMR of mPEG-PLGA (CDCl3)
Reference
[1] Park C, Choi J C, Choi Y H, et al. Synthesis of super-high-molecular-weight poly-
γ-glutamic acid by bacillus subtilis subsp chungkookjang. Journal of Molecular
Catalysis B-Enzymatic 2005; 35: 128-133.