Biomaterials surface characterization

A. M. Belu, D. J. Graham and D. G. Castner, Time of flight secondary ion mass spectrometry techniques and applications for the characterization of biomaterial surfaces, Biomaterials, 24, 3635 3653 (2003). 

Knowledge of the surface structure of CaHAP panicles is fundamentally needed not only in medical and dental sciences but also in application of synthetic CaHAP particles to bioceramics and adsorbents for biomaterials, because the affinity of CaHAP surface to biomaterials is an important factor in all the cases. The surface structure of CaHAP was investigated by various means including infrared (IR) (38,39), NMR (40). TPD (41), and XPS (42). Among these methods, IR spectroscopy is most appropriate for the surface characterization of CaHAP particles. 

Brunette, P. M., The effect of surface topography on cell migration and adhesion, in Surface Characterization of Biomaterials Progress in Biomedical Engineering, Volume 6 (B. D. Ratner, Ed.), pp. 203-217. Elsevier, New York, 1988. 

Salvati L, Grobe G Moulder J (1991) Surface characterization of polymer based biomaterials. Medical Devices Diagnostics Industry 13 96-102. 

Hsuie, G.H. Lee, S.D. Chang, P.C. Kao, C.Y. Surface characterization and biological properties study of silicone rubber material grafted with phospholipid as biomaterial via plasma induced graft copolymerization. J. Biomed. Mater. Res. 1998, 42, 134-147. 

Society for Biomaterials. 17,000 Commerce Parkway, Suite C, Mt.Laurel, NJ 08054, U.S.A. Phone + 1 856-439-0826, Fax +1 856-439-0525. E-mail info biomaterials.org. URL http // www.biomaterials.org/. Holds annual conference provides awards to students and researchers in the field and offers networking via special interest groups in many areas, including tissue engineering, drug delivery, surface characterization and modification, and orthopaedic biomaterials. Sponsors publication of Journal of Biomedical Materials Research Part A and Part B and Biomaterials Forum, the official news magazine of the Society. 

The blood-materials interactions section contains a review article dealing with surface characterization. Consideration of the surface structure of biomaterials is critical to every study in this volume. This section contains 16 chapters dealing with the choice of in vivo and in vitro methods of biomaterials evaluation, biomaterials selection and modification, and cellular interactions with candidate surfaces. Individual papers dealing with the use of dogs, baboons, and goats for in vivo blood-materials evaluation can be found together with in vitro methods. There are also several contributions on polyurethanes, which are prime candidates for use in blood contacting devices. 

In recent years the surface characterization of biomaterials has been forcefully emphasized (1—3). Unfortunately, a clear understanding of how surface characterization can be of value to biomaterials research, development, and production has, in many cases, not been realized. This chapter addresses the subject of surface characterization of biomaterials by considering three aspects of the problem first how surfaces differ from the bulk of materials second, how the important parameters of surfaces can be measured and what new techniques might be developed and finally, how surface characterization can help in understanding and predicting the biocompatibility (and in particular, the blood compatibility) of synthetic materials. 

Th ree primary reasons why surface characterization is important to biomaterials science are (1) surface identification (chemistry, structure, and reproducibility assurance), (2) contamination detection (reproducibility assurance), and (3) correlation between surface structure and biocompatibilitv. 

Because of the preliminary nature of this study, we did not use the steps of biomaterial surface preparation and characterization suggested as Level One (minimum level) tests by two recent study groups of the National Heart, Lung, and Blood Institute (41, 42). Neither bulk nor surface properties were analyzed, and the surfaces were not confined to a dust-free environ-... 

Surface characterization is very important in the development of blood-compatible biomaterials, since the surface characteristics of the polymer have been linked to polymer-tissue and polymer-blood interactions. Further information on surface characterization of biomaterials can be found elsewhere (20, 21). 

B.D. Ratner, Surface characterization of biomaterials by electron spectroscopy for chemical analysis. 

Bulk characterization yields information on the macroscopic properties of the biomaterial such as thermal, mechanical, solubility, optical, and dielectric properties. Surface characterization yields morphological information that is critical for interfacing the implant or drug delivery device with the host tissue. This could be achieved by microscopic and spectfoscopic methods. Next in the hierarchy is the characterization of processes such as biodegradation mechanism and kinetics under biomimetic in vitro conditions. Cases of implanted device failure need to be assessed by systematic interrogation of explanted medical devices. After knowing the basic characteristics of the biomaterial, real-time investigation of in vivo processes plays a major role in the successful journey of an implant. 

Surface characterization by spectroscopic techniques yields information on the functional groups and elemental composition on the surface of polymeric biomaterials. The most common spectroscopic tools used for biomedical polymers are X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), secondary ion mass spectrometry (SIMS), and Fourier transform infrared spectroscopy (FTIR) (diffuse reflectance and attenuated total internal reflectance modes). Each of these techniques is discussed in the succeeding text. 

Buchko, C.J., K.M. Kozloff, and D.C. Martin. 2001. Surface characterization of porous, biocom-patible protein polymer thin films. Biomaterials 22 1289. 

Y J Kim, 1K Kang, M W Huh and S C Yoon, Surface characterization and in vitro blood compatibility of poly (ethylene teiephthalate) immobilized with insulin and/or heparin using plasma glow discharge, Biomaterials, 1999 21(2) 121-30. 

Ratner BD, ed. (1988). Surface Characterization of Biomaterials. Amsterdam Elsevier. 

H.-Y. Yeh and J.-C. Lin, Surface characterization and in vitro platelet compatibility study of surface sulfonated chitosan membrane with amino group pro-tection-deprotection strategy . Journal of Biomaterials Science Polymer Edition, vol. 19, no. 3, pp. 291-310,2008. 

Mathieu, H.J. (2008) Surface characterization in biomaterials applications. /. Surf. Anal, 14, 293-298. 

In order to determine the composition and structure of a biomaterial surface different methods which provide varying degrees of information are commonly used (Fig. 6). Surface-sensitive infrared spectroscopy suppHes the characteristic absorption bands of functional groups with an informational depth of 0.1-10 pm by measurement in attenuated total reflectance (IR-ATR). In the case of samples with rough surfaces photoacoustic spectroscopy (PAS), which allows an informational depth of approximately 20 pm, can be used [72]. The achieved informational depths are usually larger than the thickness of the modified interface, so that the spectra include information on the bulk composition as well. As a consequence, surface-sensitive infrared spectroscopy is often not sensitive enough for the characterization of the modified surfaces. 

Electrochemical properties are other important physical surface parameters. The existing surface charge density, i.e. the surface potential, has a strong influence on protein adsorption and blood compatibility [81]. In this way the characterization of the interface charge density of a biomaterial by -potential determination delivers an important parameter for understanding blood compatibility of biomaterial surfaces [82-85]. 

Ratner BD (1988) The surface characterization of biomedical materials. In Ratner BD (ed) Progress in biomaterials engineering, vol 6. Elsevier, Amsterdam, p 13 Vidrine DW (1982) Photoacoustic Fourier transform infrared spectroscopy of solids and liquids. In Fourier transform infrared spectroscopy Fries T (1994) Deutscher Verband fiir Materialprufung, p 127 Sacher E (1988) The determination of the surface tensions of solid films. In Ratner BD (ed) Progress in biomaterials engineering, vol 6 Surface characterization of biomaterials. Elsevier, Amsterdam, p 53 Owens DK, Wendt RC (1969) J Appl Polym Sci 13 1741... 

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