Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5326_Библиотеки_им_академика_М_И_Перельмана
.pdf
Surface modification by natural biopolymer coatings on magnesium alloys 323
(a) (d)
(b)
(c)
Figure 11.16 SEM micrographs showing the surface of (a) SA1eMg, (b) SA2eMg, and (c)
SA3eMg. Optical images showing surface appearance of samples after immersion in Hank’s
solution: (d) Bare Mg (6 days), (e) SA1eMg (6 days), and (f) SA2eMg (80 days).
(e)
(f)
The results from the SA coating work are encouraging; however, some problems still
exist. Like lard coating on the surface of metals, it is hard for cells to attach on the surface.
Also, although MgSt provided a bridge between Mg and SA, a binding force is suspected.
11.5 Gelatin modification
11.5.1 Introduction to gelatin
Gelatin is a proteinaceous material derived from naturally existing collagen by controlled
hydrolysis. It is a substance of great commercial importance and always contains large
amounts of proline and hydroxyproline as well as glycine. It also exists in other residues,
includingpolar amino acids, which tend to occur in positiveand negativeclusters at points
along the tropocollagen rod surface (Clark & Ross-Murphy, 1987). Due to its numerous
324 Surface Modification of Magnesium and its Alloys for Biomedical Applications
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
9
10
8
10
7
10
6
10
5
10
4
10
3
ratio (SA2-Mg / bare Mg)
10
t
R
2
10
1
10
02468101214
R
ratio
t
16 18 20 222426 28 30
Time (day)
pH
8.0
7.5
7.0
6.5
6.0
5.5
5.0
pH
Figure 11.17 Corrosion resistance of SA-coated sample (SA2eMg) relative to bare Mg in the
immersion test.
Adapted from Ng et al. (2010).
SA
MgSt
Mg(OH)
2
HA
OCP
After immersion
Intensity (a.u)
Before immersion
10 20 30 40
50 60 70 80
2θ (°)
Figure 11.18 XRD patterns of SA2eMg before and after immersion in Hanks’ solutionfor 80 days.
Adapted from Ng et al. (2010).
advantages, such as its biological origin, biodegradability, and good biocompatibility,
together with its commercial availability at a relatively low cost, gelatin has been widely
used in biomedical applications. For example, it has long been used as a sealant for
vascular prostheses, an artificial skin (Ponticiello, Schinagl, Kadiyala, & Barry, 2000),
a carrier for drug delivery (Tabata & Ikada, 1998), and in regeneration therapy (Ponticiello
et al., 2000), among others (Zhang, Ouyang, Lim, Ramakrishna, & Huang, 2005).
Surface modification by natural biopolymer coatings on magnesium alloys 325
11.5.2 Gelatin coating on WE42 alloy
In the study by Xu, Lu, Guo, and Fang, (2010), a cross -linked gelatin with welldistributed PLGA nanoparticles composite coating on an MAO film of WE42, which
could control drug release and biocorrosion of magnesium alloy stent materials, was
prepared by sealing microcracks and holes on the surface of the MAO coating. An
equal volume of gelatin solution (6%) was mixed with different concentrations of
glutaraldehyde solution (1%, 2%, 3%) to form different degrees of cross-linked gelatin
solution. Three milligrams of paclitaxel-loaded nanoparticles fabricated by a modified
oil-in-water single-emulsion solvent evaporation/extraction technique were mixed and
sonicated with 400 m l of cross-linked gelatin solution. After being dried at room temperature, the cross-linked gelatin/nanoparticle solution was dropped onto the surface of
MAO film, and then the samples were dried at room temperature.
Figure 11.19 shows the surface morphologies of the MAO coating and cross-linked
gelatin/nanoparticles composite coating on the MAO coating. Randomly distributed
molten oxide flakes with pores and microcracks were observed on the MAO coating
surface. After being modified by the cross-linked gelatin/nanosphere composite
coating, most of the pores and microcracks of the MAO film could be overlaid, forming a smooth and uniform composite coating. This composite coating has higher
stability and better binding capacity due to the physical interlocking between the
cross-linked gelatin/nanosphere composite and MAO film.
Electrochemical tests were carried out in Hanks’ solution by potentiodynamic polarization curves and EIS. As shown in Figure 11.20, the higher the concentration
of glutaraldehyde, the higher the transfer resistance Rp of the samples. The Rp of
WE42-MAO-composite coating was much higher than that of WE42-MAO
(Rp > 100 kU cm
bare WE42 (3.5 kU cm
lower corrosion current density than the sample with MAO coating and bare WE42
samples. These results indicated that the composite coating on WE42 served as an
effective barrier against corrosive electrolyte, effectively improving the corrosion resistance of WE42.
An in vitro drug release test showed that a cross-linked gelatin/nanoparticles
coating exhibited a nearly linear relationship with no significant burst releases
2
), which was already more than 30 times higher than the Rp of the
2
). In addition, MAO-composite coated samples showed much
(a) (b)
Figure 11.19 The SEM images of (a) surface morphologies of MAO coating and
(b) cross-linked gelatin/nanoparticles composite coating on MAO coating.
)
326 Surface Modification of Magnesium and its Alloys for Biomedical Applications
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
(Figure 11.21). In addition, the release rate of paclitax el decreased as the concentration of the glutaraldehyde increased. This suggests that highly cross-linked gelatin
could more effectively decrease the diffusion of the paclitaxel and water by swelling
of the gelatin and hinder the release of paclitaxel from the PLGA nanoparticles.
A cross-linked gelatin/nanosphere composite coated WE42-MAO has increased
the corrosion resistance of WE42-MAO and controlled the drug release
(a)
–0.6
WE42-MAO-composite coating(glutaraldehyde 1%)
–0.8
–1.0
–1.2
–1.4
Potential (V)
–1.6
–1.8
–2.0
WE42-MAO-composite coating(glutaraldehyde 2%)
WE42-MAO-composite coating(glutaraldehyde 3%)
WE42
WE42-MAO
1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3
A / cm
2
(b)
WE42-MAO-composite coating(glutaraldehyde 1%)
60000
40000
Zim (ohms)
20000
0
Figure 11.20 The electrochemical characteristics of MAO coating and cross-linked gelatin/
nanoparticles coating on the MAO film in pH 7.4 Hanks’ solution at 37
WE42-MAO-composite coating(glutaraldehyde 2%)
WE42-MAO-composite coating(glutaraldehyde 2%)
WE42
WE42-MAO
0 50000 100000 150000
Zre (ohms
C.
Surface modification by natural biopolymer coatings on magnesium alloys 327
30
25
20
15
10
PTX release rate (%)
5
0
Figure 11.21 The in vitro release pattern of paclitaxel from different degrees of cross-linking
gelatin/nanoparticles composite coating.
Adapted from Xu et al. (2010).
PLGA nanoparticles
PLGA nanoparticles(glutaraldehyde 1%)
PLGA nanoparticles(glutaraldehyde 2%)
PLGA nanoparticles(glutaraldehyde 3%)
01020
Release time (days)
30 40 50
of paclitaxel-loaded PLGA nanoparticles effectively. The higher the cross-linking rate,
the better the corrosion protective ability and drug-release control properties.
11.6 Bovine serum albumin modification
11.6.1 Introduction to stearic bovine serum albumin
Serum albumins are the most abundant proteins in the circulatory system of various organisms. As the major macromolecule related to the osmotic blood pressure, they play
an important role in drug disposition and efficacy (Kamat, 2005). Many drugs and other
bioactive small molecules bind reversibly to albumin and other serum components,
which can be functionalized as carriers. The solubility of hydrophobic drugs in plasma
can be increased by serum albumin, and their delivery to cells is modulated. Therefore, it
is of great importance to study the interactions of drugs with this protein. The effectiveness of drugs depends on their binding ability (Hu, Liu, Wang, Xiao, & Qu, 2004).
11.6.2 Bovine serum albumin coating on magnesium
As reported by Liu Xin, Tian, and Chu, (2007b), the adsorbed bovine serum albumin
(BSA) resulted in decreased cathodic current and enhanced corrosion resistance, which
was ascribed to the blocking effect of the BSA-adsorbed layer, suggesting that the
adsorbed BSA coverage layer can suppress the dissolution of magnesium alloys.
328 Surface Modification of Magnesium and its Alloys for Biomedical Applications
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
Killian et al. (Killian, Wagener, Schmuki, & Virtanen, 2010) managed to prepare
an albumi n- coa ted magnesium for comparative ly smooth surfaces via silane
coupling chemistry. They used 3-aminopropyltriethoxy silane (APTES) as a silane
coupling agent and ascorbic acid (vitamin C) worked as a linker for the grafting of
BSA on the surface of the Mg substrate. BSA (400 unit/mL) was attached from
aqueous solution by soaking ma gne siu m d iscs fo r 2 4 h at room tem pe ratu re u nde r
stirring. The Mg samples steeped in albumin solution directly were used as
controls.
Results of XPS and time-of-flight secondary ion mass spectrometry (ToF-SIMS)
both showed an increased relative intensity of magnesium signals (Mg 2p; m/z ¼ 24
þ
u, Mg
) as well as a decrease in amino acid signals (N 1s; m/z ¼ 110 u, C5H8N
þ
, his-
3
tidine) on the steeped sample compa red with those of the pretreated magnesium surface
(Figure 11.22(a) and (b)). This indicated a more homogeneous, dense coverage of the
silane-coupled protein coating.
In Figure 11.23, the surface of the pretreated sample was smoother and contained
fewer defects than the steeped one. Pretreatment in organic solutions had a suppressive
effect on the formation of H
gas as a result of decreased availability of reactive sites.
2
This has led to a more uniformly coated surface that is less prone to corrosion. After
being soaked in SBF for 2.5 days, the surface of the steeped sample was not only
rougher after immersion in SBF but also exhibited larger holes because of localized
corrosion. Meanwhile, the hydrogen evolution decreased significantly from
0.12 mL/cm
2
/d for the polished sample to 0.075 mL/cm2/d after treatment with APTES
(Figure 11.24), which also indicated that the albumin coatings attached via silane
linkers on magnesium had higher corrosion resistance.
This procedure provides a simple and efficient way to attach proteins on the surface
of magnesium alloys. Because the attachment was based on silane coupling chemistry
on an OH-terminated surface, the approach should be applicable to a variety of
proteins as well as to biocompatible magnesium alloys.
Figure 11.22 Comparison of albumin attached to pretreated Mg and Mg steeped in albumin
solution. (a) XPS atomic percentages. (b) Time-of-flight secondary ion mass spectrometry
(ToF-SIMS) ratio of histidine C
Adapted from Killian et al. (2010).
þ
to magnesium Mgþ.
5H8N3
Surface modification by natural biopolymer coatings on magnesium alloys 329
(a)
(c)
(b)
(d)
(e) (f)
Figure 11.23 Optical images of (a) albumin attached via silane coupling on Mg and (b) Mg
steeped in albumin solution. Light microscopy images of (c) albumin attached via silane
coupling on Mg and (d) Mg steeped in albumin solution. Light microscopy images after 2.5 days
of immersion in SBF for (e) albumin attached via silane coupling on Mg and (f) Mg steeped in
albumin solution.
Adapted from Killian et al. (2010).
11.7 Future perspectives
After surface modification by some natural biopolymer or macromolecules, the corrosion property or biocompatibility of magnesium or its alloys have been greatly improved
in these studies. However, literature reports about natural biopolymer modification magnesium alloys are limited. Because natural biopolymers are abundant, biocompatible,
and bioactive, more potential applications of other kinds of natural biopolymers, such
as alginate agar, hyaluronic acid, and cellulose, should be developed as coatings on magnesium alloys. Table 11.6 lists the commonly used natural biopolymers. These
330 Surface Modification of Magnesium and its Alloys for Biomedical Applications
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
0.2
0.1
[ml]
2
H
0.0
Mg polished
APTES
APTES + VitC
Albumin via APTES
Albumin direct
Figure 11.24 Hydrogen evolution measurements of all of the reaction stages after 24 h of
immersion in SBF.
Adapted from Killian et al. (2010).
Table 11.6 Natural biopolymers used as biomaterials
Natural biopolymers
Modified polysaccharides Alginate agar/agarose
Cellulose Hyaluronic acid
Starch Chondroitin sulfate
Dextran Fibroin
Chitin Gelatin
Modified proteins Chitosan
Collagen Casein
biopolymers are widely used in biomedical fields, such as delivery systems, cell carriers,
and scaffolds for tissue engineering.
As for the manufacturing procedures, most of the coating preparations use a two-step
method to create a bond between layers. Firstly, MAO or hydrothermal treatment is
used to form an interlayer to get stronger binding force. Secondly, natural biopolymer
modification is performed by dipping or other methods. However, adhesion tests for
polymer or composite coatings have rarely been performed.
In addit ion, natural biopolymer-based coatings have shown the capability to act as
local drug delivery platforms. However, only a few studies have focused on this topic,
indicating that the development of these coatings is in its infancy.
Surface modification by natural biopolymer coatings on magnesium alloys 331
References
Beare-Rogers, J., Dieffenbacher, A., & Holm, J. (2001). Lexicon of lipid nutrition (IUPAC
technical report). Pure and Applied Chemistry, 73, 685e744.
Chen, Y., Song, Y., Zhang, S., Li, J., Zhao, C., & Zhang, X. (2011). Interaction between a high
purity magnesium surface and PCL and PLA coatings during dynamic degradation.
Biomedical Materials, 6, 025005.
Cheryan, M., & Rackis, J. J. (1980). Phytic acid interactions in food systems. Critical Reviews in
Food Science & Nutrition, 13, 297e335.
Clark, A. H., & Ross-Murphy, S. B. (1987). Structural and mechanical properties of biopolymer
gels. Biopolymers (pp. 57e192). Berlin, Heidelberg: Springer.
Crea, P., De Robertis, A., De Stefano, C., & Sammartano, S. (2006). Speciation of phytate ion in
aqueous solution. Sequestration of magnesium and calcium by phytate at different temperatures and ionic strengths, in NaCl
Graf, E., Empson, K. L., & Eaton, J. W. (1987). Phytic acid. A natural antioxidant. Journal of
Biological Chemistry, 262, 11647e11650.
Gu, X., Li, N., Zhou, W., Zheng, Y., Zhao, X., Cai, Q., et al. (2011). Corrosion resistance and
surface biocompatibility of a microarc oxidation coating on a MgeCa alloy. Acta
Biomaterialia, 7, 1880e1889.
Gu, X., Zheng, W., Cheng, Y., & Zheng, Y. (2009a). A study on alkaline heat treated MgeCa
alloy for the control of the biocorrosion rate. Acta Biomaterialia, 5, 2790e2799.
Gu, X., Zheng, Y., Lan, Q., Cheng, Y., Zhang, Z., Xi, T., et al. (2009b). Surface modification of an
Mg-1Ca alloy to slow down its biocorrosion by chitosan. Biomedical Materials, 4, 044109.
Hahn, B.-D., Park, D.-S., Choi, J.-J., Ryu, J., Yoon, W.-H., Choi, J.-H., et al. (2011). Aerosol
deposition of hydroxyapatitee chitosan composite coatings on biodegradable magnesium
alloy. Surface and Coatings Technology, 205, 3112e3118.
Hornberger, H., Virtanen, S., & Boccaccini, A. R. (2012). Biomedical coatings on magnesium
alloys e a review. Acta Biomaterial, 8, 2442e2455.
Hu, Y.-J., Liu, Y., Wang, J.-B., Xiao, X.-H., & Qu, S.-S. (2004). Study of the interaction
between monoammonium glycyrrhizinate and bovine serum albumin. Journal of Phar-
maceutical and Biomedical Analysis, 36, 915e919.
ISO, E., 10993e4. (2006). Biological evaluation of medical devices - Selection of tests for
interactions with blood.
Kamat, B. P. (2005). Study of the interaction between fluoroquinolones and bovine serum
albumin. Journal of pharmaceutical and biomedical analysis, 39, 1046e1050.
Kelly, F., Sinclair, A., Mann, N., Turner, A., Abedin, L., & Li, D. (2001). A stearic acid-rich diet
improves thrombogenic and atherogenic risk factor profiles in healthy males. European
Journal of Clinical Nutrition, 55, 88.
Khor, E., & Lim, L. Y. (2003). Implantable applications of chitin and chitosan. Biomaterials, 24,
2339e2349.
Killian, M. S., Wagener, V., Schmuki, P., & Virtanen, S. (2010). Functionalization of metallic
magnesium with protein layers via linker molecules. Langmuir, 26, 12044e12048.
Li, J., Cao, P., Zhang, X., Zhang, S., & He, Y. (2010). In vitro degradation and cell attachment of
a PLGA coated biodegradable Mge 6Zn based alloy. Journal of Materials Science, 45,
6038e6045.
Liu, C., Xin, Y., Tian, X., & Chu, P. K. (2007a). Corrosion behavior of AZ91 magnesium alloy
treated by plasma immersion ion implantation and deposition in artifi
fluids. Thin Solid Films, 516, 422e427.
. Biophysical Chemistry, 124,18e26.
aq
cial physiological
332 Surface Modification of Magnesium and its Alloys for Biomedical Applications
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
Liu, C., Xin, Y., Tian, X., & Chu, P. K. (2007b). Degradation susceptibility of surgical
magnesium alloy in artificial biological fluid containing albumin. Journal of Materials
Research, 22, 1806e1814.
Majeti, N. V. R. K. (2000). A review of chitin and chitosan applications. Reactive & Functional
Polymers, 46,1e27.
Ng, W. F., Wong, M. H., & Cheng, F. T. (2010). Stearic acid coating on magnesium for
enhancing corrosion resistance in Hanks’ solution. Surface and Coatings Technology, 204,
1823e1830.
Petit, R. (1999). The use of hydroxyapatite in orthopaedic surgery: a ten-year review. European
Journal of Orthopaedic Surgery & Traumatology, 9,71e74.
Ponticiello, M. S., Schinagl, R. M., Kadiyala, S., & Barry, F. P. (2000). Gelatin-based resorbable
sponge as a carrier matrix for human mesenchymal stem cells in cartilage regeneration
therapy. Journal of Biomedical Materials Research, 52, 246e255.
Ravi Kumar, M. N. (2000). A review of chitin and chitosan applications. Reactive and Func-
tional Polymers, 46,1e27.
Rinaudo, M. (2006). Chitin and chitosan: properties and applications. Progress in Polymer
Science, 31, 603e632.
Staiger, M. P., Pietak, A. M., Huadmai, J., & Dias, G. (2006). Magnesium and its alloys as
orthopedic biomaterials: a review. Biomaterials, 27, 1728e1734.
Tabata, Y., & Ikada, Y. (1998). Protein release from gelatin matrices. Advanced Drug Delivery
Reviews, 31, 287e301.
Tan, H., & Marra, K. G. (2010). Injectable, biodegradable hydrogels for tissue engineering
applications. Materials, 3, 1746e1767.
Tomozawa, M., & Hiromoto, S. (2011). Microstructure of hydroxyapatite-and octacalcium
phosphate-coatings formed on magnesium by a hydrothermal treatment at various pH
values. Acta Materialia, 59, 355e363.
Wan, Y., Xiong, G., Luo, H., He, F., Huang, Y., & Wang, Y. (2008). Influence of zinc ion
implantation on surface nanomechanical performance and corrosion resistance of
biomedical magnesium-calcium alloys. Applied Surface Science, 254, 5514e5516.
Wang, X., Zeng, X., Wu, G., Yao, S., & Lai, Y. (2007). Effects of tantalum ion implantation on
the corrosion behavior of AZ31 magnesium alloys. Journal of Alloys and Compounds, 437,
87e92.
Wong, H. M., Yeung, K. W., Lam, K. O., Tam, V., Chu, P. K., Luk, K. D., et al. (2010).
A biodegradable polymer-based coating to control the performance of magnesium alloy
orthopaedic implants. Biomaterials, 31, 2084e2096.
Wu, C., Wen, Z., Dai, C., Lu, Y., & Yang, F. (2010). Fabrication of calcium phosphate/chitosan
coatings on AZ91D magnesium alloy with a novel method. Surface and Coatings Tech-
nology, 204, 3336
e3347.
Wu, G. S., Zeng, X. Q., Yao, S. S., & Han, H. B. (2007). Ion implanted AZ31 magnesium alloy.
Materials Science Forum, 546e549, 551.
Xu, X., Lu, P., Guo, M., & Fang, M. (2010). Cross-linked gelatin/nanoparticles composite
coating on micro-arc oxidation film for corrosion and drug release. Applied Surface Sci-
ence, 256, 2367e2371.
Ye, C., Zheng, Y., Wang, S., Xi, T., & Li, Y. (2012). In vitro corrosion and biocompatibility
study of phytic acid modified WE43 magnesium alloy. Applied Surface Science, 258,
3420e3427.
Yu, S., Derr, J., Etherton, T. D., & Kris-Etherton, P. (1995). Plasma cholesterol-predictive
equations demonstrate that stearic acid is neutral and monounsaturated fatty acids are
hypocholesterolemic. The American Journal of Clinical Nutrition, 61, 1129e1139.
Соседние файлы в папке Библиотека им академика М.И. Перельмана