Size-Controllable PDHCA-β-CD Nanoparticles as Drug Carrier
tion was maintained stirring for 1 h at 140 ℃ and sub-
sequent 6 h at 200 ℃ with N purging. Then the reac-
2
on calibration curve. Each experiment was carried out in
triplicate and the average values were plotted.
tion mixture was washed with ethanol and deionized
water twice, respectively. A brown precipitate was re-
covered and dried in blast oven at 50 ℃ for 12 h to
obtain 2.967 g powder (yield 69%).
Measurements
Fourier transform infrared spectroscopy (FT-IR)
spectrum was recorded with KBr disc technique on an
FT-IR2000-104 spectrometer (ABB, USA). H NMR
1
Synthesis of PDHCA-β-CD
spectrum was recorded using an AVANCE Ⅲ NMR
spectrometer (400 MHz, Bruker, Switzerland) with
TMS as an internal standard. UV-vis spectrum was per-
formed on a UV-1100 spectrometer (Rayleigh, China) at
room temperature. Gel permeation chromatography
(GPC, Agilent 1515, HP, USA) was performed using
DMF as moving phase and calibrated with monodis-
persed polystyrene (PS) standards at a flow rate of 1.0
Various amounts of 6-SH-β-CD were dissolved in 30
mL DMF respectively. And then 1 g PDHCA was added
into the solution with ultrasonic-assistant dissolving.
With 0.5 mL triethylamine as catalyst, the reaction was
carried on at 30 ℃ for 4 h. The reaction solution was
treated by vacuum distillation to remove the solvent and
then dried at 60 ℃.
g
mL/min at 35 ℃. The glass transition temperature (T )
Preparation of PDHCA-β-CD nanoparticles
was determined by differential scanning calorimeter
(DSC822e, Mettler Toledo, Switzerland) with nitrogen
atmosphere flow rate of 50 mL/min and heating rate of
10 ℃/min within 0-150 ℃. The weight loss was
measured by thermogravimetric analyzer (TGA1100SF,
Mettler Toledo, Switzerland) with a heating rate of
15 ℃/min from 25 to 800 ℃. OCA 40 optical contact
angle measuring device (Eastern-Dataphy, China) was
used to study the hydrophobicity of the resulting poly-
mer. The size and morphology of polymer nanoparticles
were observed by scanning electron microscopy (SEM,
S-4800, HITACHI, Japan). Dynamic light scattering
The obtained PDHCA-β-CD polymers were dis-
solved in 2 mL DMF at a concentration of 1 mg/mL. A
certain amount of ultrapure water was dropped into the
solution with stirring and then stirred for another 24 h.
After purified by dialysis in distilled water for 4-5 d,
PDHCA-β-CD nanoparticles were then collected by
lyophilization.
Drug loading onto the PDHCA-β-CD nanoparticles
The DOX-loading nanoparticles were prepared by
the similar method as described above. In a typical ex-
periment, 2.5 mg DOX and 5mg polymer were dis-
solved in 5 mL DMF with stirring overnight. Then a
certain amount of ultrapure water was dropped into the
solution at room temperature followed by violent stir-
ring for 24 h. The solution was then dialyzed against
distilled water for 4-5 d. The sample was then sub-
jected to UV analysis at λ=80 nm where the nanoparti-
cles alone did not absorb (Figure S5). Quantification
was performed from the calibration curve of DOX•HCl
aqueous solution (Figure S6). Quantification of the
DOX loading will be given through the loading content
(
DLS, ALV/DLS/SLS-5022F, HOSIC Ltd, Germany)
was also applied to measure the size and size distribu-
tion of nanoparticles.
Results and Discussion
Synthesis of PDHCA-β-CD polymers
PDHCA-β-CD polymer was synthesized by Michael
addition between PDHCA and 6-SH-β-CD. The struc-
tures of intermediate products of each step were identi-
fied by FT-IR (Figure S1, Figure S2). By tuning the
feeding molar ratio of PDHCA to β-CD, a series of
PDHCA-β-CD polymers with different composition
were prepared (Table 1). The average molecular weight
of PDHCA obtained from the GPC measurements was
(%) (mass of DOX in vesicle/mass of polymer) and
loading efficiency (%) (mass of DOX in vesicles/mass
of DOX in the initial solution).
In vitro drug release from the PDHCA-β-CD nano-
particles
3
2000 g/mol.
To determine the drug release from the drug loaded
nanoparticles, 1 mL of drug-loaded nanoparticle (1 mg)
suspension was transferred to a dialysis bag (MWCO
Table 1 Synthesis of PDHCA-β-CD polymer
a
n
n
PDHCA
∶
Grafting degree /
PDHCA/g 6-SH-β-CD/g
Tg/℃
8
000-12000), and dialyzed against 25 mL of phos-
%
β-CD
phate buffered saline (PBS, pH 6.4) in dark with the
shaking rate of 120 r/min at 37 ℃ for 68 h. Then, at
different time intervals, samples of 4 mL were taken
from the medium outside of the dialysis bag at prede-
termined times and replenished the same volume fresh
medium. The amount of released DOX in the collected
samples was determined by measuring the absorbance
of the samples at 480 nm by an ultraviolet and visible
spectrophotometer. The drug concentration could be
directly calculated from the measured absorbance based
1
.0
0
0
117.4
93.1
90.1
74.2
60.5
1
00∶1
50∶1
1.0
1.0
1.0
1.0
0.0714
0.1427
0.2854
1.4272
4.90
30.2
45.1
74.9
2
5∶1
∶1
5
a
The grafting degree (GD) referring to the amount of β-CD at-
tached to PDHCA polymers was estimated from H NMR meas-
urements.
1
Chin. J. Chem. 2017, XX, 1—8
© 2017 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
3