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]