Synthesis of star-glycopolymers by Cu(0)-mediated radical polymerisation in the absence and presence of oxygen

Article abstract of DOI:10.1039/c6ra28763h

In this paper, novel star glycopolymers were synthesized via Cu(0)-mediated radical polymerisation at ambient temperature. The reaction was fast with little star-star coupling. Moreover, star glycopolymers can be obtained without removing oxygen from the polymerisation mixture. The effects of solvent and the ratio of initiator/catalyst/ligand on polymerisation were investigated, and the optimal conditions for the synthesis of star glycopolymer were determined. In addition, the binding ability between synthesised glycopolymers and concanavalin A (ConA) was studied using a turbidity test and quartz crystal microbalance-dissipation (QCM-D). Compared with linear glycopolymers, star glycopolymers showed higher binding ability to specific lectins and the strongest binding was obtained when the molecular weight was medium.

Full text of DOI:10.1039/c6ra28763h

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PAPER
Synthesis of star-glycopolymers by Cu(0)-mediated
radical polymerisation in the absence and presence
of oxygen†
Cite this: RSC Adv., 2017, 7, 8484
Hui Xue,‡a Lun Peng,‡b Yishi Dong,a Yuqing Zheng,b Yafei Luan,a Xiang Hu,a
ab
a
*
*
Gaojian Chen
and Hong Chen
In this paper, novel star glycopolymers were synthesized via Cu(0)-mediated radical polymerisation at
ambient temperature. The reaction was fast with little star–star coupling. Moreover, star glycopolymers
can be obtained without removing oxygen from the polymerisation mixture. The effects of solvent and
the ratio of initiator/catalyst/ligand on polymerisation were investigated, and the optimal conditions for
the synthesis of star glycopolymer were determined. In addition, the binding ability between synthesised
glycopolymers and concanavalin A (ConA) was studied using a turbidity test and quartz crystal
microbalance-dissipation (QCM-D). Compared with linear glycopolymers, star glycopolymers showed
higher binding ability to specific lectins and the strongest binding was obtained when the molecular
weight was medium.
Received 28th December 2016
Accepted 17th January 2017
DOI: 10.1039/c6ra28763h
www.rsc.org/advances
additional properties thanks to their compact structure and high
arm density.24 Therefore, it is of signicance to develop robust
1. Introduction
and convenient synthetic methods for obtaining well-dened star
glycopolymers.
Carbohydrates are key molecules in life. They are not only the
main energy source, but also the basis for cell identication and
intercellular signalling, due to the specic interaction with
proteins.1–4 A number of diseases, such as cancer and immune
disorders, are closely related to abnormal interactions between
sugar and protein.5–7 Although the interaction between individual
sugar molecules and protein is weak, it can be greatly enhanced
by the combination of a plurality of sugar molecules, resulting in
what is called a ‘glycoclusters effect’.8,9 In order to study the
interactions between carbohydrates and proteins, glycopolymers
with multiple pendant sugar units have been synthesized and
applied in many elds such as histological engineering, drug
controlled release, biosensors, proteome analysis and so on.10–16
It has been shown that dendritic sugar molecules and derivatives
possess high protein binding ability due to higher local concen-
tration of sugar units.17–19 Many reports demonstrated the
potential of star-polymers in medicine due to the unique struc-
ture, special hydrodynamics and multisite modication.20–23
Compared with their linear counterparts, star polymers possess
Star glycopolymers have been successfully synthesized via
Reversible Addition–Fragmentation Chain Transfer Polymeri-
sation (RAFT)25–27 and Atom Transfer Radical Polymerisation
(ATRP).28,29 However, there are disadvantages such as easily
coupling between star molecules, producing linear by-product
and needing high reaction temperature. Cu(0)-mediated
Living Radical Polymerisation (LRP) possesses many advan-
tages,30–35 although the mechanism is under debate. Glycopol-
ymers with narrow molecular weight distributions have been
successfully prepared in a well-controlled manner via room
temperature Cu(0)-mediated living radical polymerisation.36,37
Cyclodextrin-based glycoclusters/star glycopolymers were
synthesized by Haddleton and coworkers via the combination of
CuAAC Huisgen coupling and copper-mediated living radical
polymerisation.38 More recently, Davis and Haddleton showed
that well-dened PDMAEA stars with narrow molecular weight
distributions can be obtained by copper(0) mediated living
aState and Local Joint Engineering Laboratory for Novel Functional Polymeric
Materials, College of Chemistry, Chemical Engineering and Materials Science,
Soochow University, 199 Ren'ai Road, Suzhou 215123, P. R. China. E-mail: chenh@
suda.edu.cn; Fax: +86 512 65880827; Tel: +86 512 65880827
bCenter for So Condensed Matter Physics and Interdisciplinary Research, Soochow
University, Suzhou 215006, P. R. China. E-mail: gchen@suda.edu.cn; Tel: +86 512
65884406
† Electronic supplementary information (ESI) available: NMR of 4-arm initiator,
AGA and typical 4-arm star glycopolymer. See DOI: 10.1039/c6ra28763h
‡ These authors contributed equally to this work.
Scheme 1 Schematic representation of four arms star glycopolymer
via Cu(0)-mediated radical polymerisation and the specific interaction
between glycopolymers and ConA.
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radical polymerisation.39 In aqueous media, copper(0)- 15 min with constant pressure funnel. Then the mixture was
mediated radical polymerisation wherein reactive Cu(0) and stirred under nitrogen atmosphere overnight. The milky turbid
Cu(II)X2 species, obtained by disproportionation of Cu(I)X liquid was diluted with CH2Cl2 and ltered to get yellow oily
species in the presence of a diversity of N-containing ligands, liquid. The ltrate was extracted with H2O (1 ꢀ 30 mL), satu-
mediate an ultrafast living radical polymerisation of acrylates at rated NaOH solution (1 ꢀ 30 mL) and H2O (3 ꢀ 30 mL) itera-
room temperature or below. As being highlighted by Zhang tively. The organic phase was dried with anhydrous MgSO4 and
et al., it is able to rapidly achieve high molecular weights with recrystallized from methanol for three times. The product was
excellent control of molecular weight distribution, with perfect obtained as a white solid and thoroughly dried in a vacuum
retention of chain end functionality and low bi-radical termi- oven for 36 h. Yield: 36.81%. 1H NMR (CDCl3), d ppm: 4.31 (m,
nation ratio.37,40,41 Herein we report the synthesis of star glyco- 8H, –CH2–), 1.92 (m, 24H, –CH3).
polymers via room temperature Cu(0)-mediated radical
Synthesis of star poly(acryloyl-D-(+)-glucosamine). Typically,
polymerisation in aqueous media in the absence and presence AGA (0.4662 g, 2 mmol) and four-arm star initiator (0.0092 g,
of oxygen. Star glycopolymers were successfully synthesized 0.0125 mmol) were added to a round-bottom ask and dis-
with high reaction rate at room temperature without protecting solved in the solution with 3 mL DMF and 1 mL H2O and the
sugar monomers and the polymerisation can still be carried out mixture was bubbled with nitrogen to remove oxygen. H2O (2
in the presence of oxygen (Scheme 1). This method provides mL) was degassed via nitrogen bubbling in other ask, and then
a promising pathway for the synthesis of star glycopolymers in Me6-TREN (27.5 mL, 0.1 mmol) and CuBr (0.0143 g, 0.1 mmol)
different situations without degassing. In addition, the specic were added. Five minutes later, the former solution was trans-
binding ability of glycopolymers to ConA was measured by ferred into the latter ask to react for 6 hours at ambient
turbidity experiment and QCM-D, and it provides in-depth temperature. All operations in experiments were carried out in
information for designing star glycopolymers with potential the glove box. Finally, the resulting solution was dialyzed for 48
application in targeted drug delivery.42,43
hours and then freeze-dried. The conversion of the monomer
was determined by gravimetry.
Synthesis of star glycopolymer in the presence of O2. The
polymerisations were carried out with different ratios of
monomer to initiator. In a typical reaction, AGA (0.4662 g, 2
mmol) and four arms star initiator (0.0092 g, 0.0125 mmol) were
added to a round-bottom ask and dissolved in the solution
with 3 mL DMF and 1 mL H2O. CuBr (0.0143 g, 0.1 mmol) and
Me6-TREN (27.5 mL, 0.1 mmol) were dissolved in 2 mL H2O in
another ask. Then the former solution was transferred into the
latter ask to react for 2 hours at room temperature. All the
steps were carried out without degassing. The resulting solution
was dialyzed (3500 Mw cut-off) for 48 h, and then freeze-dried.
The conversion of the monomer was determined by gravimetry.
2. Experimental
2.1 Materials
2-Bromoisobutyryl bromide (Sigma-Aldrich, 98%), 3-(2-amino
ethyl methyl) amine (Me6-TREN, Sigma-Aldrich, 97%), conca-
navalin A (ConA, Sigma-Aldrich), 11-mercaptoundecanoic acid
(Sigma-Aldrich, 95%), N-hydroxysuccinimide (Sigma-Aldrich,
98%), N-(3-dimethylaminopropyl)-N0-ethylcarbodiimide hydro-
chloride (Sigma-Aldrich, 98%), D-(+)-glucosamine hydrochloride
(TCI, 98%) and acryloyl chloride (Aladdin, 96%) were used as
received. Pentaerythritol (Aladdin, 98%) was used aer dried in
vacuum oven. Deuterated chloroform (CDCl3, 99.8%) and
deuterium oxide (D2O, 99.9%) were purchased from Cambridge
Isotope Laboratories, Inc. Cuprous bromide (CuBr, J&K, 98%)
was used aer purication (washed with glacial acetic acid and
methanol, stirred for 30 min, ltrated and dried under vacuum
for 24 h). Triethylamine, anhydrous magnesium sulfate
(MgSO4), potassium carbonate (K2CO3), concentrated ammonia
solution, hydrogen peroxide (30 vol%), methanol, dime-
thylformamide (DMF) and other solvents were all purchased
from the Sinopharm Chemical Reagent Co., Ltd. (China) and
used as received. The dialysis membranes were purchased from
Solarbio Life Science, Inc. The monomer acryloyl D-(+)-glucos-
amine (AGA) was synthesized according to the ref. 44.
2.3 Binding assay of glycopolymer and ConA
Glycopolymer (5 mg) and ConA (1 mg) were dissolved in 1 mL
phosphate buffered saline (PBS, pH ¼ 7.4, with 0.1 mM CaCl2
and MnCl2) respectively. Then both of the solutions (0.4 mL) were
mixed with each other, and the absorbance data were obtained in
30 minutes by UV-spectrophotometer at 25 ꢁC (l ¼ 360 nm).
The QCM-D chips (AT-cut, 5 MHz, 14 mm in diameter) were
washed by ethanol and deionized water iteratively. Both sides of
the chips were treated in ozone atmosphere for 30 minutes
respectively and then cleaned with ethanol and deionized water.
Mixture of concentrated ammonia solution, hydrogen peroxide
solution and deionized water, with ratio of 1 : 1 : 5 in volume,
was used to boil the chips at 75 ꢁC for 10 minutes, followed by
2.2 Synthesis
Synthesis of star-initiator tetrakis(2-bromoisobutyryl) rinsing them with abundant deionized water. The chips were
pentaery-thritolate. Dried pentaerythritol (1.36 g, 10 mmol), dipped in 1 mL ethanol solution of 11-mercaptoun-decanoic
triethylamine (8.4 mL, 60 mmol), and tetrahydrofuran (THF, 30 acid (0.2 M) overnight and then washed with ethanol.
mL) were added to a dry three-necked ask with a magnetic bar. Dried chips were dipped in 1 mL PBS solution of N-hydrox-
The reaction mixture was bubbled with nitrogen for 10 min in ysuccinimide
and
N-(3-dimethylaminopropyl)-N0-ethyl-
an ice bath, the mixed solution of 2-bromoisobutyryl bromide carbodiimide hydrochloride (0.05 M respectively) and then
(7.9 mL, 60 mmol) and THF (10 mL) was added dropwise in rinsed with deionized water. The QCM-D chips were placed in
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the uid and exposed to the solution. Detection in QCM-D possess the best disproportionation efficiency in H2O, and
experiments was carried out in ow-through mode with a ow efficiently mediated the polymerisation process.45,46 Consid-
rate of 10 mL minꢂ1 at 25 ꢁC. The baseline was set up by passing ering the solubility of the initiator and disproportionation
the PBS (with 0.1 mM CaCl2 and MnCl2) that mentioned earlier efficiency of catalyst, the experiments were carried out in the
through for about 4.5 hours. Then freshly prepared ConA mixed solvents of DMF/H2O or DMSO/H2O. In order to deter-
solutions (PBS with 0.1 mM CaCl2 and MnCl2, 1 mg mLꢂ1) were mine the optimal condition for the synthesis of four-arm star
passed through for about 3 hours to obtain the adsorption glycopolymers, polymerisations with different solvent compo-
plateau. Aer that, the chips were washed with the former PBS sitions and ratios of bromine/cuprous bromide/ligand (Br/Cu/L)
to remove loosely attached protein.
ratios were conducted in the present work.
It can be seen from Table 1 that for the same polymerisation
time, the conversion increases with increasing water content of
the solvent, indicating that Cu(0) is formed more efficiently in
water and then enhances the initiation of the polymerisation.
For example, when DMF/H2O is 1 : 1, polymer with molecular
weight of 18 700 and PDI ¼ 1.45 was obtained aer 6 h.
Meanwhile, with the increasing of water content in the mixed
solvent, the polymer's GPC trace shows that the shoulder peaks
at high molecular weight portion taper and disappear in Fig. 1a.
It seems that couplings between star molecules are signicantly
inhibited, which offer an effective solution to the termination
problem in the synthesis of star glycopolymers. However, when
the water content increases to 75%, the polymer molecular
weight is much higher than theoretical value with lower
conversion rate within the same reaction time, no matter in the
mixture of H2O with DMF or DMSO. Moreover, the PDIs become
high (>2.2). It is possibly due to the poor solubility of the
initiator in water. At the very beginning, few initiator molecules
dissolve in the solvent, and more initiators dissolve with the
progress of polymerisation. Since the propagation time of each
initiator is different, tails appear at the low molecular weight
part of GPC curves, and PDIs broaden. From this we can draw
a conclusion: when the volume ratio of DMF/H2O is 1 : 1, the
solvent is suitable for the synthesis of star glycopolymers
(Fig. 2).
2.4 Characterization
1H NMR spectra of the polymers were recorded on an Agilent
400 MHz nuclear magnetic resonance (NMR) instrument, using
D2O as the solvent. 13C NMR spectra of the polymers were
recorded on an INOVA 300 MHz nuclear magnetic resonance
(NMR) instrument using D2O as solvent. The molecular weights
and molecular weight distributions of the polymers were
measured on a waters 1515 gel permeation chromatography
(GPC) system equipped with a PL aquagel-OH MIXED-M
column using PEG as the standard sample. A mixture of milli-
pore water containing 70% of 0.2 M NaNO3, 0.1 M NaH2PO4
with a pH of 7 and 30% methanol was used as the mobile phase
and was delivered at a ow rate of 1 mL minꢂ1. GPC traces were
acquired by an Agilent PL-GPC 50 gel permeation chromato-
graph system equipped with a refractive index detector and
using a 5 mm Guard, 5 mm MIXED-D column. PMMA was used as
the standard samples and DMF containing 0.05 mol Lꢂ1 lithium
bromide was used as the eluent at a ow rate of 1 mL minꢂ1
.
The measurement was operated at 50 ꢁC. The binding ability of
glycopolymers and ConA was measured by Ultraviolet spectro-
photometer on a Shimadzu (Kyoto, Japan) UV-3600. The quartz
crystal microbalance-dissipation (QCM-D, HRBio, Suzhou,
China) measurements primed with water or PBS at a speed of 10
mL minꢂ1 and 25 ꢁC were conducted using a Q-Sense-
E4instrument (Q-Sense, Sweden) with control soware (Reso-
nant Probes GmbH, Goslar, Germany) to analyse the data.
3.2 Inuence of ratios of initiator/catalyst/ligand
Br/Cu/L ratio is a key parameter in the activation/deactivation
process, and thus has an effect on the polymerisation rate
and controllability. To make sure full complexation of Cu(0)
with Me6-TREN, the ratio 1 : 1 (Cu/L) was used. Experiments
3. Results and discussion
3.1 Effect of solvent in the polymerisation
Cu(0)-mediated LRP is
a robust technique for polymer with different ratios of initiator/catalyst were carried out to
synthesis. As previously reported the complex Cu(I)/Me6-TREN investigate the effect of catalytic ratio on the synthesis of
Table 1 The glycopolymers obtained by polymerisation in different solvents with certain ratios of Br/Cu/L
c
Solvent ratios
(V)
Time
(h)
Conversion
(%)
Mn
Solvent
[M]/[I]a
Br/Cu/Lb
1 : 2 : 2
Mn(th)
(g molꢂ1
)
PDIc
DMF/H2O
1 : 0
9 : 1
3 : 1
1 : 1
1 : 1
1 : 3
1 : 3
6
6
6
6
2
2
2
40
40
40
40
40
40
40
21.0
29.1
34.2
36.7
75.7
11.0
13.5
8500
Bimodal
9000
11 500
13 400
14 400
28 900
4800
1.85
1.67
1.45
1.55
2.20
2.33
10 400
18 700
29 200
34 600
37 300
DMF/H2O
DMF/H2O
DMSO/H2O
1 : 1 : 1
5800
a
b
Monomer/initiator. The initial concentration of monomer [M(AGA)]0 is 0.33 mmol mLꢂ1
.
(Initiator ꢀ 4)/catalyst/ligand. c Obtained by aqueous
GPC.
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3.3 Kinetic of the polymerisation of AGA
Polymerisation system with Br/Cu/L (1 : 1 : 1) in the solvent of
DMF/H2O (1 : 1) was chosen for kinetic investigation, which
possesses moderate polymerisation rate and controllability.
ln([M0]/[M]) shows a linear relationship with time in (Fig. 3a),
and the rst order kinetics indicate that the radical concentra-
tion is constant. Molecular weight of the polymer increases
linearly with the conversion and slightly diverges (especially at
higher conversion) from the theoretical molecular weight. The
reason is that the hydrodynamic radii of star molecules are
smaller than linear ones with the same molecular weight in
solution. As linear PMMA is used as standard samples in DMF
GPC, the measured molecular weights by GPC are lower than
the theoretical molecular weights. We found that the measured
molecular weights by NMR are slightly higher than the GPC
values and are close to the theoretical molecular weights (Table
S1 and Fig. S5†). During the whole polymerisation, the poly-
dispersity index remains at about 1.5.
Fig. 1 (a) Aqueous GPC traces of star-polymers polymerised in solvent
with different DMF/H2O ratios and Br/Cu/L ¼ 1 : 2 : 2, polymerisation
time ¼ 6 hours. (b) GPC traces of star-polymers polymerised in
different solvent with Br/Cu/L ¼ 1 : 1 : 1, polymerisation time ¼ 2
3.4 Synthesis of star glycopolymers in the presence of O2
For the synthesis of sugar macromolecules in living organism,
the presence of oxygen is unavoidable. However, removing
oxygen from the polymerisation mixture is required for the
hours. [M(AGA)]0 ¼ 0.33 mmol mLꢂ1
.
acrylamide star glycopolymers. Since a four-arm initiator was
used, Br/Cu here refers to the initial molar ratios of (initiator ꢀ
4)/catalyst. It can be seen that the polymerisation rate increases
and PDI broadens slightly when the ratio of Br/Cu changes from
1 : 2 to 1 : 0.4. Low Br/Cu ratio is in favour of polymerisation
regulation, while high Br/Cu ratio helps to accelerate the poly-
merisation. There's no shoulder in all of the three GPC curves,
which indicates that this polymerisation system can reduce
star–star coupling.
Fig.
3 (a) Kinetic plots of polymerisation of star poly(acryloyl-
D-(+)-glucosamine) at 25 ꢁC. (b) Dependence of the theoretical
Fig. 2 (a) Molecular weight results measured by aqueous GPC and (b) molecular weights, the molecular weights and PDIs on conversions
the GPC curves of star-glycopolymers polymerised with different of star polymer. Polymerisation conditions: DMF/H2O ¼ 1 : 1, Br/Cu/L
ratios of Br/Cu/L. Conditions: DMF/H2O ¼ 1 : 1, polymerisation time ¼ ¼ 1 : 1 : 1, Mn and PDI obtained by DMF GPC. [M(AGA)]0 ¼ 0.33
2 hours. [M(AGA)]0 ¼ 0.33 mmol mLꢂ1
.
mmol mLꢂ1
.
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traditional free radical polymerisation or living radical poly-
merisation systems, which is bound to affect the researches on
in situ synthesis of sugar macromolecules in biological systems.
Previous studies have shown that AGET, ATRP and other poly-
merisation systems containing reducing components have
a certain ability to endure oxygen.47–49 Cu(0) is a good reductant
which will react with oxygen, so we wonder whether the present
system can still proceed in the presence of oxygen, since much
Cu(0) will be produced in the disproportionation process.
To ensure the amount of Cu(0) is enough to catalyse the system
in the presence of oxygen, the ratio of Br/Cu/L (1 : 2 : 2) was chosen.
As shown in Fig. 4, the polymerisation can still move on with a high
conversion in the presence of oxygen. Polymers with different
molecular weights (from 7500 to 25 000) were easily obtained by
changing the monomer/initiator (M/I) ratios, and the molecular
weight distributions were kept reasonably narrow. Previous reports
of the molecular weight distributions of star glycopolymers
synthesized by RAFT polymerisation could reach to 1.9.25 Relatively
narrow molecular weight distributions of star glycopolymers
ranging from 1.1 to 1.5 can be obtained via ATRP and the combi-
nation of SET-LRP/click chemistry, whose polymerisations were
carried out for 15 to 24 hours in the absence of oxygen.29,38 The
tolerance to oxygen and shorter polymerisation time guarantee our
approach more possibilities in complex systems.
Fig. 5 Turbidity measurement of glycopolymers with ConA. S means
star glycopolymers and L means linear glycopolymers. The number
behind means the molecular weight.
life activities.11 The strength of binding between multiple
ligands and lectin depends on ligand structure, molecular
skeleton freedom,50 binding-site density51,52 and molecular
weight.53,54
The binding abilities between synthetic star glycopolymers
and lectins were rst investigated through detecting changes of
the mixed solution's turbidity, and the experimental results are
shown in Fig. 5. The gure shows that the absorbance of star
glycopolymer solution increases obviously, on the contrary, no
change appears in linear molecules with a similar molecular
weight and concentration, which indicates that the star glyco-
polymers possess a better specic binding ability with lectin.
Chances are that star molecules tend to form crosslinkings with
different lectins, and thereby more particles precipitate from
3.5 Effects of different glycopolymers on specic binding to
lectin
The specic interaction between sugar and lectin is the basis for
intercellular signal transduction, and plays a vital role in many
Fig. 4 (a) Molecular weight results measured by aqueous GPC and (b)
the GPC traces of star-glycopolymers polymerised in the absence or
presence of O2. Polymerisation conditions: DMF/H2O ¼ 1 : 1, Br/Cu/L Fig. 6 (a) Plots of the frequency changes and (b) protein absorption of
¼ 1 : 2 : 2, 2 h. [M(AGA)]0 ¼ 0.33 mmol mLꢂ1 (DP ¼ 40, 80), [M(AGA)]0 QCM in response to ConA (0.1 mg mLꢂ1), PBS, and glycopolymers
¼ 0.0825 mmol mLꢂ1 (DP ¼ 10).
8488 | RSC Adv., 2017, 7, 8484–8490
(1 mg mLꢂ1).
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the solution, leading to more obvious turbidity change.
Furthermore, the star glycopolymer with Mn ¼ 4700 shows the
highest binding rate to ConA, and with the further increasing of
molecular weight, the changing rate of turbidity gradually
decreases, which coincides with the results from previous
studies.9,27 Both results of the present work and other reports
show that higher molecular weights do not always enhance
binding with proteins, and molecular weight optimization is
necessary. To obtain more information about the interactions
between glycopolymer and ConA, QCM-D data (Fig. 6) were
used. For better comparison, we calculated the relative binding
(the frequency change aer polymer injection divided by the
frequency change before polymer injection) of different poly-
mers. It shows that star glycopolymers show higher binding
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˜
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A series of star glycopolymers were synthesized via Cu(0)-
mediated radical polymerisation. The effects of solvent
composition and ratio of initiator/catalyst/ligand were investi-
gated and the optimized condition was determined. When
a mixed solvent of DMF : H2O ¼ 1 : 1 is used, both good
dissolution of the oil-soluble initiator and efficient dispropor-
tionation of Cu(I) can be achieved. A fast polymerisation rate
and relatively good controllability can be obtained when the
ratio of Br/Cu/L is 1 : 1 : 1. In the present work, we nd that the
polymerisation can still proceed and star glycopolymers with
different molecular weights are able to be obtained in the
presence of oxygen. The turbidity and QCM-D results show that
star glycopolymers possess better specic binding ability to
lectin than linear ones, and the star glycopolymers with
medium molecular weights show higher specic binding
potency. The star glycopolymers conveniently synthesized can
nd applications in the delivery of drugs, the study of the
biomolecular interactions between carbohydrates and proteins,
and for the fabrication of other sugar-based functional mate-
rials. The approach to prepare glycopolymers in the presence of
oxygen provides a facile way for in situ polymerisations that can
guarantee more possibilities in complex biological systems.
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