Platinum(iv) prodrugs with long lipid chains for drug delivery and overcoming cisplatin resistance

Article abstract of DOI:10.1039/c8cc02791a

Platinum(iv) prodrugs of clinically used cisplatin and oxaliplatin with two axial long lipid chains were developed for nanoparticle delivery to combat cisplatin resistance.

Full text of DOI:10.1039/c8cc02791a

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Platinum (IV) Prodrugs with Long Lipid Chains for Drug Delivery
and Overcoming Cisplatin Resistance
Received 00th January 20xx,
Accepted 00th January 20xx
Qiling Chen#a, Yuanyuan Yang#a, Xun Lina, Wen Maa, Gui Chena, Wenliang Lib,
Xuefeng Wang*c, Zhiqiang Yu*a
DOI: 10.1039/x0xx00000x
www.rsc.org/
To demonstrate this strategy, mPEG5000ꢀbꢀPLA6000 was employed to
encapsulate Pt(IV) prodrugs of cisplatin and oxaliplatin to form
nanoparticles (M(CisPt) and M(OxaPt)). These Pt(IV) prodrugs
containing nanoparticles could be endocytosed by the cancer cells,
naturally circumventing the cellular pathway of internalizing small
moleculeꢀbased Pt drugs by cells which adopts passive diffusion as
well as copper transporter mediated active transportation as the
major internalization pathway1. Moreover, the nanoparticle
encapsulation brings with additional protection of the Pt drugs by
polymers, which reduces the thiolꢀmediated detoxification of them.
Here, optimized formulation, triggered drug release and subsequent
biological evaluation on resistant ovarian cancer cells were
performed.
Platinum(IV) prodrugs of clinically used cisplatin and oxaliplatin
with two axial long lipid chains were developed for nanoparticle
delivery to combat cisplatin resistance.
Because of their exceptional antiꢀcancer efficacy, cisplatin and
oxaliplatin have been widely used as firstꢀline antiꢀcancer regimens
either alone or in combination therapies.1ꢀ3 Nonetheless, the
therapeutic outcomes are compromised by drug resistance and great
side effects.4ꢀ6 Drug resistance against platinum drugs firstly arises
from the difficulty of drugs in entering the cancer cells.7ꢀ9 Moreover,
platinum drugs are susceptible to deactivation by intracellular
reductants, i.e. methionine, glutathione (GSH), and metallothioꢀ
nein.10ꢀ13 Therefore, they have to be administrated at higher doses
once drug resistance arises, leading to further formidable systemic
toxicity. One possible way to overcome resistance and reduce
CisPt(IV) and OxaPt(IV) were synthesized by oxidizing
cisplatin and oxaliplatin with hydrogen peroxide (H2O2) and
subsequently attaching two axial long lipid chains to the Pt(IV)
toxicity is engineering platinum drugs into nanoparticleꢀbased drug
14ꢀ16
delivery systems.3,
Nanoparticles can ameliorate pharmacoꢀ
kinetic profiles, enhance cell internalization, and improve drug
stability by modulating size, surface properties, and targeting
capacities.17ꢀ22 However, it remains a challenging task to load
cisplatin and oxaliplatin into conventional nanoꢀcarriers because of
limited functional groups for drug conjugation and poor
hydrophilicity/hydrophobicity for drug encapsulation.
A
mPEG5000-b-PLA6000
DMF/H2O
i)
ii)
To address these issues, starting from cisplatin and oxaliplatin,
we developed Pt(IV) prodrugs (CisPt(IV) and OxaPt(IV)) with two
long lipid chains into axial positions (Scheme 1) and encapsulated
these prodrugs with FDA approved biodegradable polymer methoxyl
Cisplatin
CisPt(IV)
M(CisPt)
B
poly ꢀ (ethylene glycol) ꢀ block ꢀ poly (lactic acid) (mPEG5000ꢀbꢀ
24
PLA6000) .23,
The lipid chain endows lipophilicity into Pt(IV)
Endocytosis
drugs, providing with the possibility of incorporating them into
amphiphilic nanoꢀcarriers, which ultimately improves cellular uptake
of platinum drugs.25 In addition, compared to Pt(II), Pt(IV) prodrugs
are more resistant to deactivation by reductants and sequestration
owing to their exceptional chemical stability.26 Once in the cells,
with abundant intracellular GSH, inert Pt(IV) prodrugs can be
triggered to be reduced to toxic Pt(II) and then kill the cancer cells.27
DNA binding
mPEG5000-b-PLA6000
:
CisPt(IV):
Cisplatin:
Scheme 1. The schematic illustration of the process of preparing
M(CisPt) and its mechanism to combat cisplatin resistance.
Cisplatin was oxidized to quadrivalent CisPt(IV) and modified with
two axial long lipid chains to form CisPt(IV), which was
encapsulated into biodegradable polymer mPEG5000ꢀbꢀPLA6000 to
form M(CisPt) (i: H2O2; ii: hexadecyl isocyanate) (A). The pathway
of micelles to enter the cells and possible pathway after endocytosis
was shown (B).
a.Guangdong Provincial Key Laboratory of New Drug Screening, School of
Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515,
China.
b.School of Pharmacy, Jilin Medical University, Jilin 132013, China
c. Department of Obstetrics and Gynecology, Zhujiang Hospital, Southern Medical
University, Guangzhou 510282, China.
Electronic Supplementary Information (ESI) available: [details of any
supplementary information available should be included here]. See
DOI: 10.1039/x0xx00000x
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spheres (Figure S1). CisPt(IV) and OxaPt(IV) were successfully diffuse the drugs out of the biopolymer. In contrast, it was relatively
1
synthesized and proved by characterization of HNMR (Figure S2), stable at pH 7.4. In the presence of GSH, the platinum could be
ESIꢀMS (Figure S3) and IR (Figure S4). The long lipid chains released rapidly in a short time. That was because GSH could reduce
endow CisPt(IV) and OxaPt(IV) with possibility for encapsulation of hydrophobic CisPt(IV) into relatively hydrophilic cisplatin, which
drugs. Here various formulations via drug encapsulation by promotes the release of Pt in the polymer matrix. Above results
mPEG5000ꢀbꢀPLA6000 were studied and appropriate nanoparticle size indicated that the CisPt(IV) loaded drug delivery system showed
and loading efficiency were monitored (Figure 1, Figure S5). The sensitivity for both acid and GSH. As acidic environment and high
mean diameters of M(CisPt) and M(OxaPt) increased concentration of GSH are present in tumor cells, such system is
correspondingly as the drug to polymer feed ratio increased from expected to release the active component rapidly during the
0.01 to 0.4 (Figure 1A and Figure S5A). The polymer dispersity treatment process.
index (PDI) for M(CisPt) and M(OxaPt) ranged from ~0.1 to ~0.4,
which indicated all nanoparticles formed have moderate
A
B
polydispersity (Figure 1B and Figure S5B). The zeta potentials for
both M(CisPt) and M(OxaPt) were almost kept at around ꢀ20 mV
(Figure 1C and Figure S5C), suggesting that the drug to polymer
feed ratio in the range of 0.01 to 0.4 has no significant impact on the
zeta potential for both systems. Furthermore, the Pt loading ratios
were increased correspondingly as the drug to polymer feed ratio
increased from 0.01 to 0.4, but became similar when the drug to
polymer ratio was at 0.2 and 0.4 (Figure 1D and Figure S5D). Based
on the above characterization results, we selected the drug to
polymer ratio at 0.2 as the optimized ratio in the following study.
To prove the formation of nanoparticles, the morphology and
diameter of micelle obtained were evaluated using TEM and DLS
(Figure 2). Specifically, both M(CisPt) and M(OxaPt) were spherical
in shape and had a smooth surface without any aggregation, with a
diameter of 140 nm and 120 nm, respectively. This was further
confirmed by DLS (Figure 2C), showing average diameters of 220
nm and 178 nm for M(CisPt) and M(OxaPt), respectively. The
discrepancy in diameter between TEM and DLS could be
contributed to shrinkage of samples during the drying process in the
TEM sample preparation.
200nm
100nm
C
D
25
20
15
10
5
120
100
80
60
40
20
0
10 mM GSH
pH 5.0
pH 7.4
M(CisPt)
M(OxaPt)
178nm
PDI=0.106
220nm
PDI=0.177
0
10
100
1000
10
20
Time (h)
30
40
Mean Diameter (nm)
Figure 2. Characterization of M(CisPt) and M(OxaPt). TEM
images of representative nanoparticles of M(CisPt) (A), M(OxaPt)
(B) and DLS of M(CisPt) and M(OxaPt) (C) as well as the drug
release profiles of M(CisPt) at pH 7.4, pH 5.0 and in the presence of
10 mM GSH (D).
M(CisPt)
M(CisPt)
A
B
250
0.5
0.4
0.3
0.2
0.1
200
150
100
To gain further insight into the toxicity of M(CisPt) and
M(OxaPt) against cancer cells, A2780 (cisplatin sensitive) and
A2780DDP (cisplatin resistant) cells were chosen. Dose dependent
behaviors of cellular viability of A2780 and A2780 DDP at 48 h
were shown in Figure 3A, respectively. On A2780 cells, cisplatin
and M(OxaPt) showed almost similar toxicity against the cells.
M(OxaPt) was much more toxic than oxaliplatin on the cells.
However, M(CisPt) was the most effective. Nevertheless, on the
resistant A2780DDP cells, cisplatin was less effective. Oxaliplatin
and M(OxaPt) were almost the same in cell killing. Notably,
M(CisPt) was the most effective on the resistant cells. To further
describe this, the half inhibitory concentration (IC50) based on Pt as
well as the resultant drug resistance fold for all drugs were shown in
Figure 3B. Cisplatin showed IC50 values of 2.7 ± 0.6 µM and 24 ±
1.45 µM Pt on A2780 and A2780DDP cells, which indicated a drug
resistance fold of 9. For oxaliplatin, the IC50 were 0.86 ± 0.1 µM and
2.08 ± 0.47 µM on A2780 and A2780DDP respectively with a drug
resistance fold of 2.4. It seemed that cells resistant to cisplatin did
not show resistance to oxaliplatin. Notably, M(CisPt) had the lowest
IC50 values on both cells lines (0.0067 ± 0.001 µM on A2780 and
50
0
0.0
0.01 0.05 0.1
0.2
0.4
0.01 0.05
0.1
0.2
0.4
Drug to polymer ratio (w/w)
Drug to polymer ratio (w/w)
M(CisPt)
M(CisPt)
C
D
8
6
0
-10
-20
-30
4
2
0
0.01 0.05 0.1
0.2
0.4
0.01 0.05
0.1
0.2
0.4
Drug to polymer ratio (w/w)
Drug to polymer ratio (w/w)
Figure 1. Formulation optimization of the nanoparticles of
M(CisPt). Mean diameter (A), PDI (B) Zeta potential (C) and Pt
loading at various drug to polymer ratios (D) were shown.
In vitro platinum release behavior of M(CisPt) was studied at pH 0.0205 ± 0.0034 µM on A2780DDP). The resistance fold of M(CisPt)
7.4, pH 5.0 and in the presence of 10 mM GSH respectively (Figure was 3.1.
2D). At pH 7.4 which mimics the pH values in the blood circulation
The platinum drugs could finally target DNA in the cancer cells
and normal tissue28, less than 15% platinum was released even up to via formation of PtꢀDNA adduct, disrupting the DNA duplicates and
12 h, while there is 43% of M(CisPt) at pH 5.0. However, in the eventually leading to apoptosis. The uptake of Pt by A2780 and
reductive environment (10 mM GSH), 100% of platinum released A2780DDP cells were measured by ICPꢀMS after treatment of the
after 36 h. The results indicated that the release behavior of M(CisPt) cells at 5 h and 9 h. It could be observed that drug uptake by the cell
was highly dependent on the reducing agents and acid hydrolysis. lines were in a cell line and time dependent manner (Figure 4A). For
The acid and GSH could benefit the platinum release. In the acid almost all drug treated groups, as the time increased, more drugs
environment (pH 5.0), the polymer could be easily degraded to were internalized for both cell lines. However, it seemed that A2780
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took more cisplatin and oxaliplatin than A2780DDP cells at the same 4 h and monitored by flow cytometry (Figure 4D). Results showed
time point. The less uptake of free drugs cisplatin and oxaliplatin that as time gone by, more and more M(CisPt/RhB) were
may explain the drug resistance for them. Moreover, the drug uptake endocytosed into cells and this internalization was continuous and
of M(CisPt) and M(OxaPt) had shown almost the same on both progressive from 2 h to 4 h.
A2780 and A2780DDP cells, which were more than cisplatin and
Cisplatin is considered to induce cell and cycle arrest and
oxaliplatin. Thus, the nanoparticles helped to increase the drug apoptosis.19 To evaluate whether M(CisPt) and M(OxaPt) had
internalization greatly and may circumvent the intracellular similar impact on the cell fate, especially for cell cycle arrest and
pathways and biological barriers of the free drugs, which resulted in apoptosis, flow cytometry experiments and cell cycle analysis were
the increase of intracellular drug accumulation and the enhanced carried out (Figure S6 and Figure S7). Results showed that the PBS
cellular cytotoxicity.
treated cells were mostly in the G1 phase. However, when dosed
with M(CisPt) and M(OxaPt), the ratio of cells in S phase increased
significantly, while G1 phase decreased dramatically. In the G1
phase, the biosynthetic activities of the cell reach a high rate and cell
stores more proteins, enlarges the number of organelles, and grows
bigger.31 During the S phase, DNAs start to duplicate and the
amount of DNA is doubled. Most cells stay in S phase when exposed
to Pt based drug indicated that the DNA replication process is
disrupted in the presence of M(CisPt) and M(OxaPt) and fail to
move to the next phase. The S phase disruption effect could be due
to the association of platinum drugs to DNA structure and blockade
of the DNA helix, which could lead to inhibition of cell division and
finally results in cell apoptosis.
A2780
A2780DDP
A
Cisplatin
M(CisPt)
Cisplatin
Oxaliplatin
M(CisPt)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Oxaliplatin
M(OxaPt)
M(OxaPt)
Pt concentration (µM)
A2780 A2780DDP
Pt concentration (µM)
A2780
9 h
A2780DDP
B
10
8
30
20
A
5 h
5 h
9 h
300
200
100
0
400
300
200
100
0
***
***
***
6
***
4
10
0
***
2
***
0
Figure 3. In vitro evaluation of M(CisPt) and M(OxaPt) on
ovarian cancer cells. Cytotoxic assay by MTT of cisplatin,
oxaliplatin, M(CisPt) and M(OxaPt) on cisplatin sensitive A2780
cells and cisplatin resistant A2780DDP cells (A). The IC50 values
and the drug resistance fold were then derived (B). Significance is
defined as *** p<0.001.
D
B
120
100
80
60
40
20
0
PBS
2 h
*
4 h
**
***
To further study the specific internalization pathway, uptake of
M(CisPt) in the presence of various endocytosis inhibitors were
performed (Figure 4B). Results showed that minimal uptake by the
cells was found at 4 °C, indicating this process is ATP dependent
endocytosis.29 Moreover, chlorpromazine, genistein and sodium
azide were used as endocytosis inhibitors to further determine the
internalization pathway of M(CisPt). Sodium azide works as an
electron transport chain inhibitor19, while chlorpromazine and
genistein are routinely used to inhibit clathrinꢀmediated endocytosis
and caveolaeꢀmediated endocytosis, respectively30. It could be
clearly found that the cell lines cultured with sodium azide and
genistein had less uptake compared to the PBS treated control group.
However, cells treated with chlorpromazine exhibited the least
uptake, indicating the pathway of M(CisPt) by cancer cells is
majorly clathrinꢀmediated endocytosis. Taken together, M(CisPt)
adopts different internalization pathways from small moleculeꢀbased
Pt drugs.
To visualize the intracellular internalization pathway of
M(CisPt). A fluorescent dye Rhodamine B (RhB) was coꢀloaded to
label the nanoparticles (M(CisPt/RhB)). Treatment of the cells with
M(CisPt/RhB) for 2 h and imaging of the cells by confocal laser
scanning microscopy (CLSM) were performed (Figure 4C). It
showed that M(CisPt/RhB) were in the cell cytoplasm, indicating the
nanoparticles were in the cell plasma. To further quantify the
intracellular uptake, cells were treated with M(CisPt/RhB) for 2 h to
***
Fluorescence Intensity
DAPI
RhB
Merged
C
40µm
40µm
40µm
Figure 4. Intracellular uptake of Pt(IV) loaded nanoparticles. Pt
uptake of M(CisPt) and M(OxaPt) by A2780 and A2780DDP cells
were measured by ICPꢀMS (A). Different from the internalization
pathway of cisplatin via passive diffusion, the mechanism of uptake
of M(CisPt) was studied in the presence of various endocytosis
inhibitors (B). To visualize the nanoparticles, A2780DDP cells were
treated with M(CisPt/RhB) and imaged at 4 h. DAPI was used to
stain the cell nucleus (blue). The red fluorescence comes from RhB
in the nanoparticles (C). To quantify the nanoparticle uptake, flow
cytometry was used to monitor the fluorescence intensity in the
A2780 cells at 2 h and 4 h (D). Significance is defined as * p < 0.05,
** p < 0.01; *** p<0.001.
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In summary, an acid and reduction sensitive Pt(IV) prodrug 17.Y. Wen, H. R. Kolonich, K. M. Kruszewski, N. Giannoukakis, E.
delivery system was developed and optimized to overcome cisplatin
resistance. The Pt(IV) prodrug micelle exhibited rapid drug release
S. Gawalt and W. S. Meng, Molecular pharmaceutics, 2013, 10,
1035ꢀ1044.
under acid and high concentration reducing agent conditions. These 18.M. E. Davis, Z. Chen and D. M. Shin, Nature Reviews Drug
systems could release toxic Pt drugs rapidly in human ovarian cancer Discovery, 2008, 7, 771ꢀ781.
cells and showed greater toxicity to A2780DDP cells. What’s more, 19.W. Li, M. Jiang, Y. Cao, L. Yan, R. Qi, Y. Li and X. Jing,
the endocytic mechanisms of this system were ATP dependent and Bioconjugate chemistry, 2016, 27, 1802ꢀ1806.
multiple receptorꢀmediated. Further, most cells were arrested in S 20.K. Wang, Q. Huang, F. Qiu and M. Sui, Current medicinal
phase after treatment of M(CisPt) and M(OxaPt), which resulted in chemistry, 2015, 22, 4118ꢀ4136.
apoptosis. Therefore, the present study suggested a new strategy for 21.H. Wang, Z. Lu, L. Wang, T. Guo, J. Wu, J. Wan, L. Zhou, H. Li,
overcoming cisplatinꢀresistance by delivering and activating
platinum drugs in cancer cells.
Z. Li and D. Jiang, Cancer research, 2017, 77, 6963ꢀ6974.
22.Y. Yang, X. Wang, G. Liao, X. Liu, Q. Chen, H. Li, L. Lu, P.
Zhao and Z. Yu, J. Colloid Interface Sci., 2018, 509, 515ꢀ521.
The authors would like to thank the financial support from
National Natural Science Foundation of China (81773642), 23.J. W. Singer, B. Baker, P. De Vries, A. Kumar, S. Shaffer, E.
GuangdongꢀHong Kong Technology Cooperation Fund (2017
A050506016), the Science and Technology Planning Program of
Vawter, M. Bolton and P. Garzone, Advances in experimental
medicine and biology, 2003, 519, 81ꢀ99.
Guangzhou City, China (2017A020214012), the Grant of Jilin 24.H. Guan, M. J. McGuire, S. Li and K. C. Brown, Bioconjugate
Province Science & Technology Committee (No. 20180101194JC, Chem., 2008, 19, 1813ꢀ1821.
20170520149JH), the Department of Education of Jilin Province 25.Y. R. Zheng, K. Suntharalingam, T. C. Johnstone, H. Yoo, W.
(No. JJKH20170408KJ), the Youth Foundation project of Jilin
province health and family planning commission (No.2016Q053),
Lin, J. G. Brooks and S. J. Lippard, Journal of the American
Chemistry Society, 2014, 136, 8790ꢀ8798.
and the Jilin city science & technology innovation and development 26.H. Xiao, H. Song, Y. Zhang, R. Qi, R. Wang, Z. Xie, Y. Huang,
projects (No. 20166032).
Y. Li, Y. Wu and X. Jing, Biomaterials, 2012, 33, 8657ꢀ8669.
27.H. Xiao, H. Song, Q. Yang, H. Cai, R. Qi, L. Yan, S. Liu, Y.
Zheng, Y. Huang, T. Liu and X. Jing, Biomaterials, 2012, 33,
6507ꢀ6519.
28.Y. Zhang, F. Wang, M. Li, Z. Yu, R. Qi, J. Ding, Z. Zhang and
X. Chen, Advanced Science, 2018, 1700821.
29.L. Kastl, D. Sasse, V. Wulf, R. Hartmann, J. Mircheski, C.
Ranke, S. CarregalꢀRomero, J. A. MartínezꢀLópez, R. Fernándezꢀ
Chacón and W. J. Parak, ACS nano, 2013, 7, 6605ꢀ6618.
30.G. Sahay, D. Y. Alakhova and A. V. Kabanov, Journal of
controlled release, 2010, 145, 182ꢀ195.
Notes and references
1. T. C. Johnstone, K. Suntharalingam and S. J. Lippard, Chemical
reviews, 2016, 116, 3436ꢀ3486.
2. D. Wang and S. J. Lippard, Nature Reviews Drug Discovery,
2005, 4, 307.
3. P. a. Ma, H. Xiao, C. Li, Y. Dai, Z. Cheng, Z. Hou and J. Lin,
Materials Today, 2015, 18, 554ꢀ564.
4. R. Qi, Y. Wang, P. M. Bruno, H. Xiao, Y. Yingjie, T. Li, S.
Lauffer, W. Wei, Q. Chen, X. Kang, H. Song, X. Yang, X.
Huang, A. Detappe, U. Matulonis, D. Pepin, M. T. Hemann, M.
J. Birrer and P. P. Ghoroghchian, Nature communications, 2017,
8, 2166.
31.D. A. Foster, P. Yellen, L. Xu and M. Saqcena, Genes & Cancer,
2010, 1, 1124ꢀ1131.
5. H. Maeda, G. Y. Bharate and J. Daruwalla, European journal of
pharmaceutics and biopharmaceutics, 2009, 71, 409ꢀ419.
6. H. Xiao, D. Zhou, S. Liu, Y. Zheng, Y. Huang and X. Jing, Acta
Biomaterialia, 2012, 8, 1859ꢀ1868.
7. D. Zhou, Y. Cong, Y. Qi, S. He, H. Xiong, Y. Wu, Z. Xie, X.
Chen, X. Jing and Y. Huang, Biomaterials Science, 2015, 3, 182ꢀ
191.
8. M. A. Fuertes, C. Alonso and J. M. Pérez, Chemical Reviews,
2003, 103, 645ꢀ662.
9. Y. Zhang, G. Guo, B. Ma, R. Du, H. Xiao, X. Yang, W. Li, Y.
Gao, Y. Li and X. Jing, Anti-cancer drugs, 2015, 26, 698ꢀ705.
10.J. Reedijk and J. M. Teuben, in Cisplatin: Chemistry and
biochemistry of a leading anticancer drug, Verlag Helvetica
Chimica Acta, 2006, DOI: 10.1002/9783906390420.ch13, pp.
339ꢀ362.
11.Z. Guo and P. J. Sadler, in Adv. Inorg. Chem., ed. A. G. Sykes,
Academic Press, 1999, vol. 49, pp. 183ꢀ306.
12.J. Reedijk, Chemical Reviews, 1999, 99, 2499ꢀ2510.
13.Q. Yang, R. Qi, J. Cai, X. Kang, S. Sun, H. Xiao, X. Jing, W. Li
and Z. Wang, RSC Advances, 2015, 5, 83343ꢀ83349.
14.Q. Cheng and Y. Liu, Wiley Interdisciplinary Reviews:
Nanomedicine and Nanobiotechnology, 2017, 9, e1410.
15.W. Zhang, C. Li, C. Shen, Y. Liu, X. Zhao, Y. Liu, D. Zou, Z.
Gao and C. Yue, Drug Delivery, 2016, 23, 2575ꢀ2580.
16.R. Du, H. Xiao, G. Guo, B. Jiang, X. Yan, W. Li, X. Yang, Y.
Zhang, Y. Li and X. Jing, Colloids and Surfaces B: Biointerfaces,
2014, 123, 734ꢀ741.
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