Scheme. Schematic illustration of relevant nano-structures, mechanisms, and applications of biomineralization.
Physicochemical Characteristics of Biomineralization
Principle of Raman Spectroscopy
Vibrational spectroscopy such as Raman and infrared (IR) spectroscopy are usually used as high-sensitive analytical tools for biomedical research.[76–79] Raman spectroscopy is widely used in biomineralization because of its high resolution, accurate and low costs.[80–83] The spectral features of Raman spectroscopy are obtained by different interaction modes between the incident radiation and the sample, which is the inelastic scattering of the incident light caused by changes in the polarizability of the target molecules (Figure 1a ). It is a process in which the energy of the scattered photon is different from the energy of the incident photon and is described as the Raman effect.[84,85] This inelastic process puts the molecule in a vibrational state. Scattering in which the energy of the scattered photon is equal to the energy of the incident photon is often referred to as Rayleigh scattering.[86] When the energy of the scattered photon is lower than the energy of the incident photon, it is called Stokes Raman scattering, and the opposite phenomenon is called anti-Stokes Raman scattering (Figure 1a ). The Stokes-Raman signal of the molecule is stronger than the anti-Stokes signal because the overall energy state is controlled by thermal statistics.[87–90] Therefore, Stokes Raman scattering is now used to analyze minerals, phospholipids, collagen, and others in biomineralized tissues.[91–93]