**Abstract**

Animal tissues are extensively used as scaffolds for tissue engineering and regenerative therapies. They are typically subjected to decellularization process to obtain a cell-free extracellular matrix (ECM) scaffolds. It is important to identify chemical structure of the ECM scaffolds and Fourier transform infrared (FTIR) appears to be a technique of choice. In this chapter, FTIR spectra of native and decellularized buffalo aortae, buffalo diaphragms, goat skin, and native bovine cortical bone are presented. The transmittance peaks are that of organic collagen amide A, amide B, amide I, amide II and amide III chemical functional groups in both native and decellularized aortae, diaphragms and skin. In bone, the transmittance peaks are that of inorganic ν1, ν3 PO4 3−, OH− in addition to organic collagen amide A, amide B, amide I, amide II and amide III chemical functional groups. These important transmittance peaks of the tissue samples will help researchers in defining the chemical structure of these animal tissues.

**Keywords:** buffalo aorta, buffalo diaphragm, bovine bone, goat skin, Fourier transform infrared spectroscopy

## **1. Introduction**

The extracellular matrix (ECM) scaffolds primarily composed of structural collagen protein are widely used in tissue engineering and regenerative medicine [1–15]. These are usually prepared from animal tissues by decellularization process. Decellularization is the process of removal of native cells from animal tissue, leaving behind a three-dimensional network of ECM proteins while preserving the bioactivity and mechanics of the tissue. In the decellularization process, animal tissues are subjected to physical, enzymatic and chemical treatments. Physical methods of decellularization include freezing, direct pressure, sonication, and agitation [16]. Enzymatic techniques of decellularization include the use of protease (trypsin) [1–5, 8, 10, 12–15], endonucleases and exonucleases. Chemical methods of decellularization include the use of acids and alkalis (acetic acid, peracetic acid, hydrochloric acid, sulfuric acid, ammonium hydroxide), nonionic detergents (Triton X-100), ionic detergents (sodium dodecyl sulfate, sodium deoxycholate, Triton X-200) [1–15], zwitterionic detergents (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate, sulfobetaine-10, sulfobetaine-16), organic solvent (Tri(n-butyl)phosphate) [3, 10], hypertonic and

hypotonic solutions [2, 3, 8, 10, 13, 15], and chelating agents (EDTA). These reagents at higher concentrations extensively disrupt the structural proteins of ECM scaffolds and make it impossible to analyze by routine techniques [17]. Fourier transform infrared (FTIR) spectroscopy is one of the preferred technique for identification of biomolecules through the study of their characteristic vibrational movements [11, 13, 14, 18]. This technique is simple, reproducible, nondestructive to the tissue, and only small amounts of tissue (micrograms to nanograms) with a minimum preparation are required. In addition, this technique also provides molecular-level information allowing investigation of functional groups, bonding types, and molecular conformations. The characteristic peaks in FTIR spectra are molecule specific and provide direct information about biochemical composition. This chapter highlights the application of FTIR spectroscopy for characterization of native and decellularized buffalo aortae, buffalo diaphragms, goat skin, and native bovine cortical bone.
