Surface Characterization of Biomaterials

The biomaterials surface, which may only be a few atomic layers thick, constitutes the important interface between the biomaterials and the external biological environment and plays a key role in the chemical and biological actions in vitro and in vivo. Hence, in order to monitor and fathom the biological performance of biomaterials, the surface properties must be well known. Recently, surface modification of biomaterials has attracted considerable attention as selective surface properties such as cytocompatibility can be altered while desirable bulk properties such as mechanical strength can be retained. In this respect, surface characterization techniques are indispensable in this important and burgeoning research area.No single technique can provide all the information, and quite often, different analytical tools are required to address a problem related to biomaterials research. To obtain surface chemical and morphological information, spectroscopic techniques such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS), and microscopic methods such as confocal microscopy, scanning electron microscopy, atomic force microscopy (AFM) are typically carried out. Other surface characterization methods such as contact angle (CA) measurement and ellipsometry are also widely used in biomaterials research. It should be emphasized that each technique has its strengths and weaknesses, and complete characterization frequently requires more than one method. In this chapter, we introduce and describe some of the common surface characterization techniques suitable for biomaterials. Initial discussion starts with spectroscopic techniques, their operation principles, and data analysis with specific examples. The discussions related to spectroscopic characterization are focused on XPS, AES, SIMS, surface matrix-assisted laser desorption ionization mass spectrometry (Surface-MALDI-MS), infrared spectroscopy, Raman spectroscopy, electron energy loss spectroscopy and ultraviolet spectroscopy. After spectroscopic characterization techniques, this chapter focuses on microscopic characterization. This part of the chapter is specifically focused on optical, electron and confocal microscopic techniques. Microscopic technique also discusses recent advances in atomic level characterization using scanning tunnelling microscopy and AFM. Finally, the chapter deals with specific surface characterization techniques for morphology with profilometry followed by surface charge measurement using CAs. The last section of the chapter deals with ellipsometry, a specular optical technique which provides unequalled capabilities for thin film metrology. Throughout this chapter, specific discussions are focused on examples based on applications as well as advantages, disadvantages, and challenges. © 2013 Elsevier Inc. All rights reserved.