Добавил:
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_5568_Библиотеки_им_академика_М_И_Перельмана

.pdf
Скачиваний:
0
Добавлен:
30.08.2026
Размер:
52 Мб
Скачать
344 Surface Modication of Magnesium and its Alloys for Biomedical Applications
These are all well studied and commonly used in industrial applications, and an excellent review on these methods was written by Gray and Luan (2002). While such methods may protect magnesium, the use of bare magnesium is not ideal for biomedical application in general, or neural application specically. Instead, this chap­ter will concentrate on methods to apply polymeric coatings.
12.7.1 Pretreatment of magnesium surface
It should be noted that pretreatment through use of the surface-altering methods listed above has been found to improve the adhesion strength of subsequent polymeric coating (Hornberger et al., 2012; Ostrowski et al., 2013). Some refer to the use of such pretreatment as a two-stepcoating method and application of coating to bare, unaltered Mg surfaces is a one-st epmethod. No studies are currently published in which neural cells have been grown on Mg substrates coated through a two-step pro­cess, but it seems reasonable to assume that this method might increase surface rough­ness of this applied polymer coating. It has been reported that nano-rough gold surfaces cause high rates of cell death by necrosis in neurons (Brunetti et al., 2010). Therefore, the question remains whether the increase in adhesion strength achieved through pretreatments is an optimal strategy for creating neural biomaterials.
12.7.2 Dip-coating
Dip-coating is one of the most facile coating methods. It involves dissolving monom ers in a solvent and then dipping the magnesium substrate. Coating thickness can be controlled by the viscosity of the monomer solution; the number of dipping cycles; and most importantly, the dipping rate. This type of coating can be used to apply ther­moplastic polymers as well as polymers that need to be dissolved in organic solvents. Although this method is simple, it offers less exact control over coating thickness and uniformity. This method is well suited for thicker coatings, tens of microns to the sub­millimeter range. However, lm thickness per dipping cycle varies widely with the vis­cosity of the dipping solution and rate of dipping. Zomorodian et al. (2013) reported lms of less than 5 mm thickness (see Figure 12.5) when coating magnesium with PEI dispersed with nano-sized hydroxyapatite (HA). In addition, they showed that agglomeration of their nanoparticles resulted in defects in the uniformity of the coating, which can be seen in Figure 12.5, panel C. Others have also reported difculties in creating uniform, nonporous coatings through the dipping process (Xu & Yamamoto,
2012). In the eld of neural biomaterials, this may not necessarily be a drawback, as a
certain degree of porosity is desirable for many neural applications. However, being able to exert strict control over the features of polymer coatings on magnesium is impor­tant since the degradation of magnesium is highly unpredictable. Even with the reported defects, magnesium samples with the coating in the study were stable in DMEM solu­tion for 3 months.
Application of polymer coatings onto magnesium substrates through a dipping pro­cess is the most reported method, most likely because it requires no special equipment. This method also has value as an experimental tool because thickness parameters can
Surface modication of magnesium by functional polymer coatings for neural applications 345
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
(a) (b)
(c)
Figure 12.5 a) SEM image showing 4e5 mm coating achieved through dipping. (b) High- magnication image showing un-agglomerated nano HA. (c) Agglomerated HA and associated defect in surrounding polymer lm. (d) Agglomerated HA particles as seen from the surface of the coated Mg substrate. Reproduced from Zomorodian et al. (2013).
(d)
be easily changed by addition of dipping cycles or altering the speed of dipping. Such simple optimization methods could be especially valuable when designing neural guid­ance conduits, where wall thickness is a key parameter (Kokai, Lin, Oyster, & Marra,
2009).
12.7.3 Spin-coating
Spin-coating is an ideal method for applying a uniform thin coating onto a at sub­strate. The substrate is secured to a spinning stage, and then the coating material is applied to the center of the substrate and allowed to spread evenly over the surface through centripetal acceleration forces.
Spin-coating is a good method for spreading uniform thin lms of polymers that are extremely sticky or hydrophobic and suitable for coating at, axi-symmetrical substrates. It is also a good researchtool for screening potentialcoating materials because this method is compatible with a wide variety of coating materials including solvent-dissolved solu­tions,thermoplastics, and coatings that require additionalprocessingsuch as curingor sin­tering.However, it is less effective for coating cylindrical or oddly shapedobjects and may present edge effects if it is used to coat non-axi-symmetric shapes (Boellaard, Pham,
Sarro, & Burghartz, 2002,pp.81e86). In addition, if the substrate to be coated has
346 Surface Modication of Magnesium and its Alloys for Biomedical Applications
any depressions of features, this method is not optimal as there is a tendency for polymer to collect in features, which results in nonuniform coating thickness (Boellaard et al., 2002, pp. 81e86). This has the potential to be a strong negative effect when coating conducting objects such as electrodes, where charge density at the surface must be closely controlled.
Altering the spinning speed changes the thickness and surface roughness of the resulting coatings. In addition, when using solvent casting methods, the choice of sol­vent may be important, as differences in vapor pressure of the solvent will result in different rates of vaporization speed and ultimately alter the morphology and charac­teristics of the resulting lm (Kamanyi, Ngwa, Luo, & Grill, 2008).
12.7.4 Spray-coating
Spray-coating is similar to dip-coating, but requi res additional equipment to create a continuous, controlled spray. Spray-coating is appropriate for polymeric material that can exist in a liquid or colloid form, which includes most of the popular synthetic biodegradable polymers. The coatings created by spraying are inherently porous in na­ture (Gray & Luan, 2002), which may be benecial in neural applications, where a degree of porosity is ideal, as previously discussed. Jo et al. recently used spray­coating of PCL in combination with aerosol deposition of bioactive nanoparticles (Jo, Li, Kim, Kim, & Koh, 2013). This combination coating method allowed the re­searchers to create a exible, uniform coating of biodegradable polymer to temper the corrosion processes of the magnesium substrate. Spray-coating is an excellent op­tion when trying to coat objects that are three dimensional, nonsymmetrical, or with topographical features. Generally, spray-coating will result in a layer of more uniform thickness than can be achieved with spin-coating (Boellaard et al., 2002, pp. 81e86).
There are a variety of sub-technologies that come under the heading of spray­coating. The previous paragraph concentrated on the spraying of colloids, but there is also thermal spray-coating, which allows for the coating of a surface in any material that is meltable (Gray & Luan, 2002). Another variation is electrostatic spray-coating (Liu, Jiang, & Malshe, 2009). In this solvent-free process, powders of solid charged particles or atomized liquids are accelerated toward a surface by the application of an electrical eld. For such a process to work, both the particles and the item to be coated must be conductive and able to carry charge. This process is advantageous in that it does not require solvents, which are often not biocompatible and need to be removed carefully, and it is more efcient, reducing the waste of coating material due to overspray, which is common with traditional spray techniques.
Wong et al. (2010) created what they called polymer membranes of PCL on mag-
nesium through layers of spray-coating. As seen in Figure 12.6, pores of different sizes can be created by changing the concentration of PCL used in the spraying apparatus. Small implants covered in these membranes were implanted into the greater trochanter of rabbits for 2 months, and an interesting nding in this study was that no evidence of excessive hydrogen gas was found, which is very different from previous studies. Based on these ndings, Wong et al. hypothesizes that implantation in different areas of the body as well as the protection provided by the coating limited the evolution of hydrogen gas to a level that was able to be absorbed easily into the body.
Surface modication of magnesium by functional polymer coatings for neural applications 347
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
(a) (b)
Figure 12.6 Porous membranes of PCL produced through spray-coating onto magnesium. The size and density of resulting pores was easily controlled by changing the density of PCL used in the spraying apparatus. LMP, low-porosity membrane; HPM, high-porosity membrane. PCL, poly-ε-caprolactone.
12.7.5 Electrospinning
In electrospinning, a liquid-phase polymer is released from a syringe into an electric eld. The eld disrupts the surface tension of the polymer, stretching the droplets until they form a thin, continuous stream from the syringe ti p. The thin bers are collected at a certain distance from the syringe tip where they are generated. Fibers produced through electrospinning can range from microns to nanometers in diameter and can be collected on a stationary plate, resulting in random alignment; o r the col­lecting p late can be rotated, which will result in controlled alignment of bers.
Electrospinning is the most promising coating method for supporting neural cell growth and adhesion (Aurand, Lampr, & Bjugstad, 2012; Subramanian et al., 2009), as it can be used to create highly porous scaffolds, such as the surface shown in
Figure 12.7, which allow ow of nutrients and waste products. The interconnected
network structure of the pores created from this method makes it more suitable than the isolate d pores created throug h other methods such as salt-leaching. In addition,
Figure 12.7 Example of an electrospun scaffold for neural tissue engineering, created from PLGA-PANi composite bers. Reproduced from Subramanian et al. (2009).
348 Surface Modication of Magnesium and its Alloys for Biomedical Applications
control of alignment of fibers creates micro and nano-patterning, and such aniso- tropic topographical cues have been shown to inuence man y factors of regeneration including neurite alignment, neurite outgrowth, formation of synaptic connections, and cell differentiation (Nectow et al., 2012). This method creates porous coatings, which might present a problem when coating magnesium substrates that need to be protected from premature degradation in the physiological environment. Possible so­lutions to that problem would be to use dual coating methods: one inner coating that is not as porous to protect the magnesium from corrosion followed by a second outer coatingthat supports active cellular adhesion, proliferation, and migration.
12.7.6 Electrophoretic deposition
Electrophoretic deposition is a two-step process by which the particles suspended in a colloid solution are collected onto a substrate. Deposition takes place in an electrochem­ical cell in which one of the electrodes is the substrate to be coated. When the potential is applied, the suspended coating particles are polarized and pulled toward the substrate (electrophoresis) to form a loose coating. The coating at this point is a powder agglom­eration and must undergo additional processing such as sintering to secure the bonds between the particles and to the substrate (Vandeperre & Van der Beist, 1999). Polymers that can be used in electrophoretic deposition must be polarizable or possess the ability to sustain induced dipoles in order for the electrophoresis to take place. Advantages of this method include that it tends to produce uniform coatings on three-dimensional substrates, and the entire exposed surface is easily coated, making it simple to coat inner and outer surfaces of cylindrical objects (Boellaard et al., 2002, pp. 81e86).
12.7.7 Electrochemical deposition
Electrochemical deposition is similar to electrophoretic deposition in that it also takes place in an electrochemical cell, but in this case, a chemical bonding process occurs, as opposed to electrophoretic deposition. In electrochemical deposition, a monomer so­lution is loaded into an electrochemical cell and the magnesium substrate serves as one of the electrodes. When voltage is applied, the monomers undergo a chemical polymerization onto the magnesium. An example of the electrochemical cell used by Sebaa et al. (2013) is shown in Figure 12.8. Advantages of electrochemical depo­sition include its relatively low cost and improved interfacial bonding between the coating material and the substrate before heat treatment or sintering. However, the uni­formity and morphology of the coating depends on the polymerization pattern or the polymer used. For example, PEDOT coating on magnesium substrates (see
Figure 12.9) appeared particulate. Luo et al. explored direct electrodeposition of
conductive polymer coating onto magnesium substrates using magnesium as a work­ing electrode in the electrochemical cell and an ionic liquid solution (Luo & Cui,
2011). Sebaa et al. compared various electrochemical deposition parameters to pro-
duce lms of uniform thickness and reduce the cost of the electrochemical deposition (Sebaa et al., 2013). The electrochemically deposited PEDOT on magnesium sub­strates was thoroughly characterized by Sebaa et al.
Surface modication of magnesium by functional polymer coatings for neural applications 349
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
Magnesium (working)
Platinum or stainless steel (counter)
Silver/silver chloride or copper (reference)
Potentiostat
10 mm
5 mm
Figure 12.8 Schematic of electrochemical cell for the direct electrodeposition of conductive polymer onto magnesium working electrode.
Figure 12.9 Representative image of morphology of PEDOT deposited on magnesium substrate by electrochemical deposition (Sebaa et al., 2013).
12.8 Evaluation of coating
Coating of the magnesium substrates will have an effect on the biological, chemical, and mechanical performance of the material. It is extremely important to evaluate how the coating changes the substrate properties, as well as the stability and strength of the coating itself. Despite this being crucial for proper evaluation of coatings and preclin­ical or clinical adoption of technologies, there is little consensus around which tests should be used.
12.8.1 Characterization of microstructure
The topography and surface roughness of objects plays an important role in deter­mining cell adhesion properties and more specically the neuroconductive and
350 Surface Modication of Magnesium and its Alloys for Biomedical Applications
neuroinductive abilities of materials in vivo. Many experimental NGCs have incorpo­rated micropatterning in an attempt to provide directional growth cues for regener ating neuritis.
To evaluate structures and features at the submicron a nd nanometer scales, higher resolving power is needed than can be provided through optical micro­scopy. Therefore, character izing micro- and nanostructure of polymeric coatings must be done through more sensitive methods such as electron microscopy, the most widely used of which is scanning electron microscopy (SEM). If the coating polymer is not conductive, it is necessary to prepare the samples with a sputter co at or to use an environmental SEM (ESEM), an excellent method for analyzing bio­logical samples as it ca n look at wetand un-sputter-coat ed samples. However, the resolution of ESEM is usually not as good as that provided by a standar d SEM set-up. Polymeric samples are delicate, and even sputter-coated samples may be damaged if the acceleration voltage used is too high.
12.8.2 Adhesion strength (ASTM tape test, ASTM
microscratch test)
While many in the literature agreed that adhesion strength is essential for a good coating material, as Hornberger et al. (2012)andXu and Yamamoto (2012) have previously pointed out, there is a dearth of concrete data being reported. Some au­thors give detailed mechanisms of how polymers and magnesium might interact (Zomorodian et al., 2013), but in most papers no physical testing results are re­ported. In addition, adhesion properties that are reported are often given for tests performed in dry conditions, which may or may not be relevant for neural and other biomedical applications.
The American Society for Testing and Materials (ASTM) is a valuab le resource for information about accepted and proper testing of the mechanical properties of materials. Strong, uniform adhesion is desirable to create mag nesium with stable coating and to predict its properties in living systems. Therefore, it is nece ssary to test the adhesion strength of the coating to the material. A simple tes t of adhesion strength is the tape test. In this test, a grid pattern is scored into the coating and then tape is applied to the scored grid and removed at a set angle an d speed. Strength of adhesion is ranked on a ve-point scale depend ing on the amount of coating that has detached from the underlying magnesium and become stuck to the tape instead. Examples of how to evaluate adhesion strength with the tape tests are shown i n
Figure 12.10.
The microscratch and closely related nanoscratch tests are techniques from which one can glean a range of information, including coating material hardness, yield strength, and Youngs modulus. This test is often done with a specialized piece of equipment, which can apply a constant and controlled force directed at an angle normal to the coating surface. This technique can be used to evaluate organic or inorganic thin lm coatings (less than 5 mm in thickness for the microscratch test and less than 800 nm for the nanoscratch test).
Surface modication of magnesium by functional polymer coatings for neural applications 351
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
Classification
5B None
4B
3B
2B
1B
0B Greater than 65%
Surface appearance
Figure 12.10 ASTM 3359 tape test classications. Reproduced from Sebaa et al. (2013).
References
after tape test
Aurand, E. R., Lampr, K. J., & Bjugstad, K. B. (2012). Dening and designing polymers and
hydrogels for neural tissue engineering. Neuroscience Research, 72(3), 199e213.
Belkas, J. S., Shoichet, M. S., & Midha, R. (2004). Peripheral nerve regeneration through
guidance tubes. Neurological Research, 26, 151e160.
Boellaard, E., Pham, P. N., Sarro, P. M., & Burghartz, J. N. (2002). Spin, spray coating and
electrodeposition of photoresist for MEMS structures - a comparison. In: SAFE 2002
Proceedings of 5th Semiconductor Advances for Future Electronics Workshop
(pp. 81e86). Utrecht: STW Technology Foundation.
Brunetti, V., Maiorano, G., Rizzello, L., Sorce, B., Sabella, S., Cingolani, R., et al. (2010).
Neurons sense nanoscale roughness with nanometer sensitivity. Proceedings of the National Academy of Sciences of the United States of America, 107(14), 6264e6269.
http://dx.doi.org/10.1073/pnas.0914456107.
Conceicao, T. F., Scharnagl, N., Blawert, C., Dietzel, W., & Kainer, K. U. (2010). Corrosion
protection of magnesium alloy AZ31 sheets by spin coating process with poly(ether imide) [PEI]. Corrosion Science, 52(6), 2066e2079. http://dx.doi.org/10.1016/j.corsci.2010.02.027.
Deal, D. N., Grifn, J. W., & Hogan, M. V. (2012). Nerve conduits for nerve repair or recon-
struction. Journal of the American Academy of Orthopaedic Surgeons, 20(2), 63e68.
Durgam, H., Sapp, S., Deister, C., Khaing, Z., Chang, E., Luebben, S., et al. (2010). Novel
degradable co-polymers of polypyrrole support cell proliferation and enhance neurite out-growth with electrical stimulation. Journal of Biomaterials Science. Polymer Edition, 21(10), 1265e1282. http://dx.doi.org/10.1163/092050609X124817518063303046.
352 Surface Modication of Magnesium and its Alloys for Biomedical Applications
Feria, M., Abad, F., Sanchez, A., & Abreu, P. (1993). Magnesium sulphate injected subcuta-
neously suppresses autotomy in peripherally deafferented rats. Pain, 53(3), 287e293.
Frost, C. M., Wei, B., Baghmanli, Z., Cederna, P. S., & Urbanchek, M. G. (2012). PEDOT
electrochemical polymerization improves electrode delity and sensitivity. Plastic and Reconstructive Surgery, 129(4), 933e942. http://dx.doi.org/10.1097/PRS.0b013
e31824422bf00006534-201204000-00024.
Gray, J. E., & Luan, B. (2002). Protective coatings on magnesium and its alloysa critical
review. Journal of Alloys and Compounds, 336(1e2), 88e113.
Guerrera, M. P., Volpe, S. L., & Mao, J. J. (2009). Therapeutic uses of magnesium. American
Family Physician, 80(2), 157e162.
Guimard, N. K. E., Sessler, J. L., & Schmidt, C. E. (2009). Towards a biocompatible,
biodegradable copolymer incorporating electroactive oligothiophene units. Macromolecules, 42(2), 502e511.
Hornberger, H., Virtanen, S., & Boccaccini, A. R. (2012). Biomedical coatings on magnesium
alloys - a review. Acta Biomaterialia, 8(7), 2442e2455.
Huang, L., Zhuang, X., Hu, J., Lang, L., Zhang, P., Wang, Y., et al. (2008). Synthesis of
biodegradable and electroactive multiblock polylactide and aniline pentamer copolymer for tissue engineering applications. Biomacromolecules, 9(3), 850e858. http://dx.doi.org/
10.1021/bm7011828.
Jo, J. H., Li, Y., Kim, S. M., Kim, H. E., & Koh, Y. H. (2013). Hydroxyapatite/poly(epsilon-
caprolactone) double coating on magnesium for enhanced corrosion resistance and coating exibility. Journal of Biomaterials Applications, 28(4), 617e625. http://dx.doi.org/
10.1177/0885328212468921 0885328212468921.
Kamanyi, A. E., Ngwa, W., Luo, W. L., & Grill, W. (2008). Effects of solvent vapor pressure
and spin-coating speed on morphology of thin polymer blend lms. Proceedings of SPIE 6935, Health Monitoring of Structural and Biological Systems 2008,69351X.
http://dx.doi.org/10.1117/12.776274.
Kehoe, S., Zhang, X. F., & Boyd, D. (2012). FDA approved guidance conduits and wraps for
peripheral nerve injury: a review of materials and efcacy. Injury, 43(5), 553e572.
Kokai, L. E., Lin, Y. C., Oyster, N. M., & Marra, K. G. (2009). Diffusion of soluble factors
through degradable polymer nerve guides: Controlling manufacturing parameters. Acta Biomaterialia, 5(7), 2540e2550.
Lago, N., Ceballos, D., Rodriguez, F. J., Stieglitz, T., & Navarro, X. (2005). Long term
assessment of axonal regeneration through polyimide regenerative electrodes to interface the peripheral nerve. Biomaterials, 26(14), 2021e2031.
Lewitus, D., Vogelstein, R. J., Zhen, G., Choi, Y. S., Kohn, J., Harshbarger, S., et al. (2011).
Designing tyrosine-derived polycarbonate polymers for biodegradable regenerative type neural interface capable of neural recording. IEEE Transactions on Neural Systems and
Rehabilitation Engineering: a Publication of the IEEE Engineering in Medicine and Biology Society, 19(2), 204e212.
Liu, H., Jiang, W., & Malshe, A. (2009). Coating for dental and orthopedic implants. JOM,
61(9), 67e69.
Luo, X., & Cui, X. T. (2011). Electrochemical deposition of conducting polymer coatings on
magnesium surfaces in ionic liquid. Acta Biomaterialia, 7(1), 441e446.
Mackinnon, S., & Dellon, A. L. (1990). Clinical nerve reconstruction with a bioreprobable
polyglycolic acid tube. Plastic and Reconstructive Surgery, 85(3), 419e424.
Makadia, H. K., & Siegel, S. J. (2011). Poly lactic-co-glycolic acid (PLGA) as biodegradable
controlled drug delivery carrier. Polymers, 3(3), 1377e1397.
Surface modication of magnesium by functional polymer coatings for neural applications 353
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
Navarro, X., Krueger, T. B., Lago, N., Micera, S., Stieglitz, T., & Dario, P. (2005). A critical
review of interfaces with the peripheral nervous system for the control of neuroprostheses and hybrid bionic systems. Journal of the Peripheral Nervous System : JPNS, 10(3), 229e258.
Nectow, A. R., Marra, K. G., & Kaplan, D. L. (2012). Biomaterials for the development of
peripheral nerve guidance conduits. Tissue Engineering. Part B Reviews, 18(1), 40e50.
Ostrowski, N., Lee, B., Enick, N., Carlson, B., Kunjukunju, S., Roy, A., et al. (2013). Corrosion
protection and improved cytocompatibility of biodegradable polymeric layer-by-layer coatings on AZ31 magnesium alloys. Acta Biomaterialia, 9(10), 8704e8713.
Pan, H. C., Sheu, M. L., Su, H. L., Chen, Y. J., Chen, C. J., Yang, D. Y., et al. (2011).
Magnesium supplement promotes sciatic nerve regeneration and down-regulates inammatory response. Magnesium Research : Ofcial Organ of the International Society for the Development of Research on Magnesium, 24(2), 54e70.
Perlman, J. M. (2006). Intervention strategies for neonatal hypoxic-ischemic cerebral injury.
Clinical Therapeutics, 28(9), 1353e1365.
Prutchi, D., & Norris, M. (2005). Design and development of medical electronic instrumenta-
tion. Hoboken, NJ: Wiley and Sons.
Sebaa, M. A, Dhillon , S., & Liu, H. (2013). Electroche mical deposition and evaluation of
electrically conductive polymer coating on biodegradable magnesium implants for neural applications. Journal of Materials Science. Materials in Medicine, 24(2), 307e316.
Song, G., Atrens, A., & Wu, X. (1998). Corrosion behaviour of AZ21, AZ501 and AZ91 in
sodium chloride. Corrosion Science, 40(10), 1769e1791.
Subramanian, A., Krishnan, U. M., & Sethuraman, S. (2009). Development of biomaterial
scaffold for nerve tissue engineering: biomaterial mediated neural regeneration. Journal of Biomedical Science, 16, 108.
Vandeperre, L. J., & Van der Beist, O. O. (1999). Electrophoretic deposition of materials.
Annual Review of Materials Science, 29(1), 327e352.
Volpe, S. L. (2013). Magnesium in disease prevention and overall health. Advances in Nutrition,
4, 3785e3835.
Wallace, G. G., Teasdale, P. R., Spinks, G. M., & Kane-Maguire, L. A. (2008). Conductive
electroactive polymers: intelligent polymer systems. Boca Raton, FL: CRC press.
Witte, F., Hort, N., Vogt, C., Cohen, S., Kainer, K. U., Willumeit, R., et al. (2008). Degradable
biomaterials based on magnesium corrosion. Current Opinion in Solid State & Materials Science, 12(5e6), 63e72.
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(8), 2084e2096.
Xu, L., & Yamamoto, A. (2012). Characteristics and cytocompatibility of biodegradable polymer
lm on magnesium by spin coating. Colloids and Surfaces. B, Biointerfaces, 93,67e74.
Zomorodian, A., Garcia, M. P., Moura e Silva, T., Fernandes, J. C., Fernandes, M. H., &
Montemor, M. F. (2013). Corrosion resistance of a composite polymeric coating applied on biodegradable AZ31 magnesium alloy. Acta Biomaterialia, 9(10), 8660
e8670.