Raman spectroscopy, differentiation

Figure 1.13 Raman spectra for a number of transition metal oxides supported on y-AI203 [75,102], Three distinct regions can be differentiated in these spectra, namely, the peaks around 1000 cm-1 assigned to the stretching frequency of terminal metal-oxygen double bonds, the features about 900 cm 1 corresponding to metal-oxygen stretches in tetrahedral coordination sites, and the low-frequency (<400 cm-1) range associated with oxygen-metal-oxygen deformation modes. Raman spectroscopy can clearly complement IR data for the characterization of solid catalysts. (Reproduced with permission from The American Chemical Society.)...

A variety of physical methods has been used to ascertain whether or not surface ruthenation alters the structure of a protein. UV-vis, CD, EPR, and resonance Raman spectroscopies have demonstrated that myoglobin [14, 18], cytochrome c [5, 16, 19, 21], and azurin [13] are not perturbed structurally by the attachment of a ruthenium complex to a surface histidine. The reduction potential of the metal redox center of a protein and its temperature dependence are indicators of protein structure as well. Cyclic voltammetry [5, 13], differential pulse polarography [14,21], and spectroelectrochemistry [12,14,22] are commonly used for the determination of the ruthenium and protein redox center potentials in modified proteins. 

R. E. Kast, G.K. Serhatkulu, A. Cao, et al., Raman spectroscopy can differentiate malignant tumors from normal breast tissue and detect early neoplastic changes in a mouse model. Biopolymers, 89, 235-241 (2008). 

H.R.H. Ali, H.G.M. Edwards, M.D. Hargreaves, T. Munshi, I.J. Scowen and R.J. Telford, Vibrational spectroscopic characterisation of sahneterol xinafoate polymorphs and a preliminary investigation of their transformation using simultaneous in situ portable Raman spectroscopy and differential scanning calorimetry. Anal. Chim. Acta, 620, 103-112 (2008). 

Except for very low values (< 600 cm ), frequencies can normally be measured to high precision (< 5 cm ) using infrared or Raman spectroscopy. Similar or better precision is available for frequencies calculated analytically (Hartree-Fock, density functional and semi-empirical models), but somewhat lower precision results where numerical differentiation is required (MP2 models). 

For HNO3, Raman spectroscopy was used to determine concentrations, and hence equilibrium constants, in HN03(aq) solutions. But this technique is often not possible in other systems because vibrational or electronic transitions that can be used to differentiate between the ion and the molecule are not present, and other techniques must be used. As we do so, we must keep in mind that the different techniques are based upon assumptions that lead to the measurement of the equilibrium concentration. For example, a lightscattering technique such as Raman spectroscopy usually relies on the assumption that the concentration of the species in solution is proportional to the intensity of the observed band. 

Since the 1990s several groups have used Raman spectroscopy to distinguish between normal and neoplastic tissue. The first studies looked at differentiating between normal tissue and advanced cancers in the breast [2] and... 

Abstract Raman spectroscopy can potentially offer a non-invasive, information rich biochemical snap-shot of living human cells, tissues or material-cell tissue constructs rapidly (seconds-minutes), without the need of labels or contrast enhancers. This chapter details the exciting potential and challenges associated with the use of this analytical technique in tissue engineering (TE). The use of Raman spectroscopy in three intricately linked areas of TE will be considered (1) the characterisation of the various scaffolds and smart materials, (2) the biochemical analysis of cellular behaviour important in TE (e.g. differentiation) and (3) the use of Raman spectroscopy for the analysis of tissue/extra-cellular matrix (ECM) formation in vitro or possibly in vivo. 

Raman spectroscopy can be used for live, in situ, temporal studies on the development of bone-like mineral (bone nodules) in vitro in response to a variety of biomaterials/scaffolds, growth factors, hormones, environmental conditions (e.g. oxygen pressure, substrate stiffness) and from a variety of cell sources (e.g. stem cells, FOBs or adult osteoblasts). Furthermore, Raman spectroscopy enables a detailed biochemical comparison between the TE bone-like nodules formed and native bone tissue. Bone formation by osteoblasts (OB) is a dynamic process, involving the differentiation of progenitor cells, ECM production, mineralisation and subsequent tissue remodelling. 

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