Fourier transform infrared spectroscopy (FTIR) application chemical characterization of enamel,dentin and bone

Fourier transform infrared spectroscopy (FTIR) has been used extensively for chemical characterization of mineralized tissues in the past few decades. FTIR is an ideal technique to analyze chemical structural properties of natural materials, since the frequencies of several vibrational modes of organic and inorganic molecules are active in the infrared. This review discusses the use of FTIR methodology, highlighting the attenuated total reflection (ATR) sampling mode, particularly for characterization of enamel, dentin and bone tissues. Enamel, dentin and bone, are composed of an organic and a mineral phase. The mineral phase is characterized essentially as nonstoichiometric substituted apatite, being the carbonate and phosphate spectral peaks the main representative of these phase. Organic matrix of the post-eruptive enamel is small (～1% weight (wt)). The dentin and bone organic phases are mainly composed of type I collagen that appears as spectral bands of amide I, amide II, amide III bands. Furthermore, synthetic apatite materials are being designed for total or partial replacement, restoration or augmentation of these biological tissues with FTIR assistance.     

Applications of Raman Spectroscopy in Dentistry: Analysis of Tooth Structure

Abstract: Tooth enamel is the most mineralized tissue in the human body, and in this article the use of Raman spectroscopy for the analysis of tooth structure, a comparison with synthetic apatites, and use in dentistry are described. Spectral peaks that are related to dental hard and soft tissues are discussed, which provide crucial data in understanding the chemical structural properties of dentin and enamel. The Raman spectrum of dentin confirms the presence of crystalline phosphate-based minerals in dentin. Both dentin and enamel consist of two primary components: an inorganic or mineral phase that closely resembles hydroxyapatite and the Raman spectrum of dentin that confirms the presence of crystalline phosphate-based minerals in dentin. Hence, the mineral phase in dentin and enamel may be characterized essentially as nonstoichiometric substituted apatite. The presence of carbonate (A and B type) incorporated in the hydroxyapatite lattice is also confirmed by the presence of spectral bands. The organic phase, which is mainly composed of type I collagen, is confirmed by the spectral bands of amide I and amide II bands, tryptophan, and phenylalanine. Furthermore, these spectral bands associated with organic and inorganic parts of the enamel and dentin are useful in predicting early formation of carries formation.     

Micro‐Raman spectroscopy and VP‐SEM/EDS applied to the identification of mineral particles and fibres in histological sections

Histological sections of a patient affected by an important respiratory disease were analysed firstly by optical microscope(OM)—crossed polarisers—to identify the presence of incorporated inorganic particles, with particular attention to the fibrous ones. Then, the particles/fibres that were found were studied both with micro‐Raman spectroscopy and variable‐pressure scanning electron microscopy with energy‐dispersive spectroscopy (VP‐SEM/EDS). The two techniques allowed the in situ characterisation of the inorganic phases without disintegration of the organic matter. Micro‐Raman spectroscopy was able to identify the vibrating chemical groups of the mineral phase associated with the inorganic grain while the crystalline structure was preserved by the biological system. The VP‐SEM/EDS characterisation, defining the elemental chemical composition of the analysed particle/fibre, allowed confirmation of the mineral phase deducible from spectroscopic data or its identification with certainty when the spectroscopic data were not exhaustive. Copyright © 2009 John Wiley & Sons, Ltd.     

Characterization and evaluation of cytotoxicity of biphasic calcium phosphate synthesized by a solid state reaction route

Calcium phosphate compounds have been widely studied for biomedical applications because of their chemical and structural similarity to the mineral phase constituting bone and teeth. In this work, biphasic calcium phosphate ceramics (HAP/β-TCP), with tunable phase composition ratio, were synthesized by a solid state reaction process. The effect of varying the heat treatment temperature (700, 800, 900, 1000, and 1100 °C) on the formation of the ceramic materials and their related cytotoxicity were examined. The phase composition and morphology of the prepared ceramic powders were characterized by X-ray diffraction and scanning electron microscopy, and the functional groups were analyzed using Fourier transform infrared spectroscopy and Raman spectroscopy. Cell culture experiments, using murine macrophages, showed that the synthesized HAP/β-TCP materials did not exhibit cytotoxicity regardless of the doses assayed or the differences in composition ratio of HAP/β-TCP, suggesting the potential of HAP/β-TCP for biological applications.     

Effect of strontium ranelate on bone mineral: Analysis of nanoscale compositional changes

Strontium ranelate has been used to prevent bone loss and stimulate bone regeneration. Although strontium may integrate into the bone crystal lattice, the chemical and structural modifications of the bone when strontium interacts with the mineral phase are not completely understood. The objective of this study was to evaluate apatite from the mandibles of rats treated with strontium ranelate in the drinking water and compare its characteristics with those from untreated rats and synthetic apatites with and without strontium. Electron energy loss near edge structures from phosphorus, carbon, calcium and strontium were obtained by electron energy loss spectroscopy in a transmission electron microscope. The strontium signal was detected in the biological and synthetic samples containing strontium. The relative quantification of carbon by analyzing the C_K edge at an energy loss of ΔE = 284 eV showed an increase in the number of carbonate groups in the bone mineral of treated rats. A synthetic strontium-containing sample used as control did not exhibit a carbon signal. This study showed physicochemical modifications in the bone mineral at the nanoscale caused by the systemic administration of strontium ranelate.     

Approximate chemical analysis of volcanic glasses using Raman spectroscopy

The effect of chemical composition on the Raman spectra of a series of natural calcalkaline silicate glasses has been quantified by performing electron microprobe analyses and obtaining Raman spectra on glassy filaments (~450 µm) derived from a magma mingling experiment. The results provide a robust compositionally‐dependent database for the Raman spectra of natural silicate glasses along the calcalkaline series. An empirical model based on both the acquired Raman spectra and an ideal mixing equation between calcalkaline basaltic and rhyolitic end‐members is constructed enabling the estimation of the chemical composition and degree of polymerization of silicate glasses using Raman spectra. The model is relatively insensitive to acquisition conditions and has been validated using the MPI‐DING geochemical standard glasses 1 as well as further samples. The methods and model developed here offer several advantages compared with other analytical and spectroscopic methods such as infrared spectroscopy, X‐ray fluorescence spectroscopy, electron and ion microprobe analyses, inasmuch as Raman spectroscopy can be performed with a high spatial resolution (1 µm²) without the need for any sample preparation as a nondestructive technique. This study represents an advance in efforts to provide the first database of Raman spectra for natural silicate glasses and yields a new approach for the treatment of Raman spectra, which allows us to extract approximate information about the chemical composition of natural silicate glasses using Raman spectroscopy. We anticipate its application in handheld in situ terrestrial field studies of silicate glasses under extreme conditions (e.g. extraterrestrial and submarine environments). © 2015 The Authors Journal of Raman Spectroscopy Published by John Wiley & Sons Ltd     

Effects of structure and composition of the CaP composite coatings on apatite formation and bioactivity in simulated body fluid

The surface properties of biomaterials determine the interactions between biomedical devices and the surrounding biological environment. The surface modification of biomaterials is extensively recognized as a key strategy in the design of the next generation of bone implants and tissue engineering. In this study, the highly ordered octacalcium phosphate (OCP) coating and OCP/protein coating with hierarchically porous structure in nano-micro scale were constructed on titanium substrate by electrochemically-induced deposition (ED). The formation behavior of apatite on OCP and OCP/protein coatings immersed in simulated body fluid (SBF) was investigated in physicochemical aspects. It is indicated that soaked in SBF, the OCP and OCP/protein coatings are possible to induce relevant apatite formation on their surface, and the apatite-forming behavior in body environment is depended on the chemical composition and structure of the coatings. The apatite formed on OCP/protein composite coating possesses carbonated structure, needle-like crystals in nano scale, lower Ca/P ratio and higher degree of the preferred c-axis orientation, which are similar to the mineral composition and structure in natural bone, and hence called as bone-like apatite.     

Local structure of hydroxy-peroxy apatite: A combined XRD, FT-IR, Raman, SEM, and solid-state NMR study

The synthesized hydroxyapatite (HAp) and hydroxy-peroxy apatite are studied using various techniques, such as X-ray powder diffraction, FT-IR and Raman spectroscopy, scanning electron microscopy, and solid-state NMR spectroscopy. The experimental data suggest that hydroxy-peroxy apatite contains a small amount of hydration of partially dehydroxylated hydroxyapatite phase and calcium hydroxide. The incorporation of peroxide ions into the lattice of HAp causes perturbations of the hydrogen environments and slight changes in its crystal morphology. The distance between H in some structural OH⁻ and adjacent O along the c-axis becomes longer instead of forming a hydrogen bond after the incorporation of peroxide ions.     

鲤鱼耳石的拉曼及红外光谱特征研究

鱼耳石是存在于硬骨鱼内耳中的功能性沉积体,主要由碳酸钙和有机质构成,是一种典型的天然生物矿物。鱼的内耳中共有微耳石、星耳石、矢耳石各1对。利用FTIR光谱和Raman光谱对实验室中养殖锦鲤的星耳石和微耳石进行了对比分析,结果表明微耳石的矿物相为文石,而星耳石的矿物相则为球文石,微耳石中纯文石和星耳石中纯球文石的各自独立存在为文石/球文石的矿化机理研究提供了十分优异的天然样品。分别将其与无机和生物成因的文石、球文石的Raman及FTIR图谱进行比较,发现微耳石的FTIR和Raman图谱特征介于无机成因文石和其他生物成因文石之间,而星耳石的FTIR和Raman图谱特征则与其他生物成因的球文石更为接近,这可能是由于有机物参与了生物矿化过程并起到了稳定介稳相的球文石的结果。     

拉曼光谱在危地马拉翡翠矿物组成中的应用研究

危地马拉是缅甸之外的另一个翡翠的商业性产地,危地马拉翡翠通常是多种矿物成分的集合体,其矿物组成具有特色,与缅甸翡翠的不同。以危地马拉紫色和灰绿色翡翠为研究对象,通过激光拉曼光谱测试分析,对其结构特征及共生矿物组成特点进行了研究。结果表明,危地马拉翡翠中的主要组成矿物为硬玉,并伴有多种共生矿物。危地马拉翡翠的共生矿物包括五类,其中深色共生矿物为角闪石,白云石,绿辉石和绿泥石,浅色共生矿物为磷灰石。其中角闪石,白云石,绿辉石和绿泥石也是缅甸翡翠中常见的共生矿物,而磷灰石在缅甸翡翠中几乎不可见。     

A Vibrational Spectroscopic Study of the Sulfate Mineral Glauberite

The mineral glauberite is one of many minerals formed in evaporite deposits. The mineral glauberite has been studied using a combination of scanning electron microscopy with energy dispersive X-ray analysis and infrared and Raman spectroscopy. Qualitative chemical analysis shows a homogeneous phase, composed by sulfur, calcium, and sodium. Glauberite is characterized by a very intense Raman band at 1002 cm^?1 with Raman bands observed at 1107, 1141, 1156, and 1169 cm^?1 attributed to the sulfate ν₃ antisymmetric stretching vibration. Raman bands at 619, 636, 645, and 651 cm^?1 are assigned to the ν₄ sulfate bending modes. Raman bands at 454, 472, and 486 cm^?1 are ascribed to the ν₂ sulfate bending modes. The observation of multiple bands is attributed to the loss of symmetry of the sulfate anion. Raman spectroscopy is superior to infrared spectroscopy for the determination of glauberite.     

Vibrational Spectroscopy of the Borate Mineral Priceite—Implications for the Molecular Structure

ABSTRACT

Priceite is a calcium borate mineral and occurs as white crystals in the monoclinic pyramidal crystal system. We have used a combination of Raman spectroscopy with complimentary infrared spectroscopy and scanning electron microscopy with Energy-dispersive X-ray Spectroscopy (EDS) to study the mineral priceite. Chemical analysis shows a pure phase consisting of B and Ca only. Raman bands at 956, 974, 991, and 1019 cm^?1 are assigned to the BO stretching vibration of the B₁₀O₁₉ units. Raman bands at 1071, 1100, 1127, 1169, and 1211 cm^?1 are attributed to the BOH in-plane bending modes. The intense infrared band at 805 cm^?1 is assigned to the trigonal borate stretching modes. The Raman band at 674 cm^?1 together with bands at 689, 697, 736, and 602 cm^?1 are assigned to the trigonal and tetrahedral borate bending modes. Raman spectroscopy in the hydroxyl stretching region shows a series of bands with intense Raman band at 3555 cm^?1 with a distinct shoulder at 3568 cm^?1. Other bands in this spectral region are found at 3221, 3385, 3404, 3496, and 3510 cm^?1. All of these bands are assigned to water stretching vibrations. The observation of multiple bands supports the concept of water being in different molecular environments in the structure of priceite. The molecular structure of a natural priceite has been assessed using vibrational spectroscopy.     

景德镇釉上彩绘瓷器釉上彩的Raman与EDXRF分析

釉上彩绘瓷器是我国古陶瓷中重要品类之一,具有极高的艺术价值和科学价值。采用拉曼光谱和能量色散X射线荧光分析等无损技术手段,对陶瓷釉彩的元素组成和物相组成综合分析,探讨了人们广为关注的景德镇元、 明和清代釉上彩绘瓷若干典型颜料种类的组成配方及其相应的呈色机制。研究发现景德镇古代红绿彩、 五彩、 粉彩等标本中的深红釉上彩料为赤铁矿着色,黄彩为铅锡黄着色,胭脂红彩则由含量不到0.1%的金所着色,绿料皆为二价铜离子着色。研究结果也进一步说明了Raman和EDXRF这两种无损、 微区分析技术的有效结合可以在深化陶瓷类文物的分析研究,尤其是针对图案交错复杂的多种彩绘颜料研究方面起到重要的作用。     

The effects of strontium on bone mineral: A review on current knowledge and microanalytical approaches

The interest in effects of strontium (Sr) on bone has greatly increased in the last decade due to the development of the promising drug strontium ranelate. This drug is used for treating osteoporosis, a major bone disease affecting hundreds of millions of people worldwide, especially postmenopausal women. The novelty of strontium ranelate compared to other treatments for osteoporosis is its unique effect on bone: it simultaneously promotes bone formation by osteoblasts and inhibits bone resorption by osteoclasts. Besides affecting bone cells, treatment with strontium ranelate also has a direct effect on the mineralized bone matrix. Due to the chemical similarities between Sr and Ca, a topic that has long been of particular interest is the incorporation of Sr into bones replacing Ca from the mineral phase, which is composed by carbonated hydroxyapatite nanocrystals. Several groups have analyzed the mineral produced during treatment; however, most analysis were done with relatively large samples containing numerous nanocrystals, resulting thus on data that represents an average of many crystalline domains. The nanoscale analysis of the bone apatite crystals containing Sr has only been described in a few studies. In this study, we review the current knowledge on the effects of Sr on bone mineral and discuss the methodological approaches that have been used in the field. In particular, we focus on the great potential that advanced microscopy and microanalytical techniques may have on the detailed analysis of the nanostructure and composition of bone apatite nanocrystals produced during treatment with strontium ranelate.     

Chemical and mechanical properties of snake fangs

The composition of dental tissues and their interaction determines its mechanical properties. The mechanical properties and chemical composition of the teeth of extant reptiles are still poorly studied areas. As a preliminary study the fangs of four species of snakes and a human tooth were investigated through nanoindentation and Raman spectroscopy. The average elastic modulus values for the main body of the fangs ranged from 15.3 GPa to 24.6 GPa, and 19.1 GPa for the human dentine. Raman spectroscopy and principal component analysis (PCA) showed that snake fangs are similar in composition to human dentine, both of which comprised of hydroxyapatite and an organic matrix. The elastic modulus and hardness data were correlated to the Raman spectra using partial least squares regression (PLS). The spectral features which correlated with the elastic modulus would suggest that elastic modulus is dependent on the relative protein to mineral amounts in the tooth. The form of the phosphate and the relative levels of phosphate to organic components also appear to be governing factors for elastic modulus. The PLS of Raman spectra against the hardness gave very similar results. The small differences between snake fangs and human dentine appeared to be because of carbonate content, with higher levels of carbonate in the human tooth than the snake fangs. Snake fangs should be able to withstand large lateral forces. Human dentine aids in dissipating imposed loads. This similarity in the chemical composition of the snake fangs and human dentine supported the findings of the similarities in mechanical properties, which may be attributed to the similar functional demands of these biocomposites. Copyright © 2016 John Wiley & Sons, Ltd.     

Applications of Raman Spectroscopy in Agricultural Products and Food Analysis: A Review

Abstract

Raman spectroscopy has been gaining popularity as an analytical tool due to advances in development of Raman spectrometry and the power of personal computers. Due to to its narrow and highly resolved bands, Raman spectroscopy allows for nondestructive extraction of chemical and physical information about samples and aids in rapid on-line analysis without any special sample preparation. In this review, Raman spectroscopic techniques such as dispersive Raman spectroscopy, Fourier transform Raman spectroscopy, surface-enhanced Raman spectroscopy, and spatially offset Raman spectroscopy are briefly introduced. In addition, applications of Raman spectroscopy are explored, within various fields of agricultural products and food, including fruits and vegetables, crops, meat and dairy products, oil, as well as beverages. In addition, some discussion on the importance of Raman spectroscopy as fundamental and applied research of agricultural products and food is provided.     

The pathogenesis of Randall's plaque: a papilla cartography of Ca compounds through an ex vivo investigation based on XANES spectroscopy

At the surface of attached kidney stones, a particular deposit termed Randall's plaque (RP) serves as a nucleus. This structural particularity as well as other major public health problems such as diabetes type‐2 may explain the dramatic increase in urolithiasis now affecting up to 20% of the population in the industrialized countries. Regarding the chemical composition, even if other phosphate phases such as whitlockite or brushite can be found as minor components (less than 5%), calcium phosphate apatite as well as amorphous carbonated calcium phosphate (ACCP) are the major components of most RPs. Through X‐ray absorption spectroscopy performed at the Ca K‐absorption edge, a technique specific to synchrotron radiation, the presence and crystallinity of the Ca phosphate phases present in RP were determined ex vivo. The sensitivity of the technique was used as well as the fact that the measurements can be performed directly on the papilla. The sample was stored in formol. Moreover, a first mapping of the chemical phase from the top of the papilla to the deep medulla is obtained. Direct structural evidence of the presence of ACCP as a major constituent is given for the first time. This set of data, coherent with previous studies, shows that this chemical phase can be considered as one precursor in the genesis of RP.     

Raman Spectroscopy of Biological Tissues

Abstract

This article reviews some of the recent advances in Raman spectroscopy, in areas related to natural tissues and cell biology. It summarizes some of the most widely used peak frequencies and their assignments. The aim of this study is to prepare a database of molecular fingerprints, which will help researchers in defining the chemical structure of the biological tissues introducing most of the important peaks present in the natural tissues. In spite of applying different methods, there seems to be a considerable similarity in defining the peaks of identical areas of the spectra. As a result, it is believed that preparing a unique collection of the frequencies encountered in Raman spectroscopic studies can lead to significant improvements both in the quantity and quality of spectral data and their outcomes. This article is the first review of its kind to provide a precise database on the most important Raman characteristic peak frequencies for researchers aiming to analyze natural tissues by Raman spectroscopy and will especially be of considerable assistance to those who are focusing on the analysis of cancerous tissues by Raman spectroscopy.     

红外和拉曼光谱的煤灰矿物组成研究

研究煤灰中矿物质的性质通常从矿物组成的表征入手。为了分析两种高硅铝煤灰的矿物成分,采用傅里叶变换红外光谱(FTIR)、拉曼光谱和X射线衍射(XRD)技术对煤灰样进行了测试和综合表征,将FTIR和拉曼光谱的分析结果与XRD进行了比较。FTIR结果表明,在1 100~1 000 cm-1范围内高硅铝煤灰出现最强的特征峰,例如石英峰(1 089 cm-1)和偏高岭石峰(1 042 cm-1),它们都归属于Si-O伸缩振动。对原始红外谱图进行二阶导数处理后,可获得重叠峰的峰位,有助于更完整的解析矿物吸收峰,从而获得更丰富的矿物组成信息。煤灰中硬石膏的红外和拉曼光谱发现,在1 157,1 126和674 cm-1的拉曼光谱峰与在1 151,1 120和678 cm-1的红外光谱峰振动模式分别相同且峰位接近,还存在一些完全不同的拉曼光谱与红外光谱峰,表明这两种光谱存在互补性。尽管煤灰中锐钛矿含量很低,但由于Ti-O的极化率很高,因此拉曼光谱显示锐钛矿的144 cm-1峰远远强于石英的461 cm-1峰。XRD结果表明,煤灰中主要存在石英、云母、赤铁矿、硬石膏和未知的无定形相矿物,FTIR和拉曼光谱综合分析的结果表明除了这些矿物,还存在偏高岭石、无定形氧化硅、长石、方解石和锐钛矿等。在定性分析方面,将FTIR和拉曼光谱结合起来比XRD单独获得的矿物组成信息更为详细。     

Raman spectroscopy speciation of natural and anthropogenic solid phases in river and estuarine sediments with appreciable amount of clay and organic matter

A new methodology is proposed in order to perform direct Raman measurements in sediments with high content in clay and organic matter with a reduced pre‐treatment. Following this method, different compounds were found within the samples, some of them were assigned as natural compounds (clay, iron oxide, pyrite, aragonite, calcite, silicates and quartz) and the others were included in the group that comes from the human activity (titanium oxide, phthalocyanine blue, phthalocyanine green, gypsum, calcium arsenate, lead oxide, zinc oxide, sodium sulfide and iron hydroxioxide). The study of the presence of these polluting agents and their differentiation from the compounds that belong to the sediments as natural compounds is fundamental in order to understand the mobility/retention processes of the pollutants, and thus, their bioavailability. Also the speciation studies of solid phase downstream a wastewater treatment plant can be the basis to diagnose the adequate functioning of the facility. This work shows the applicability of Raman spectroscopy to perform speciation studies in the solid phases of natural and anthropogenic compounds present in river and estuarine sediments with appreciable content in clay and organic matter. The differentiation between natural and anthropogenic compounds is of fundamental interest because the potential toxicity of a metal (i.e. arsenic) in a natural compound (i.e. arsenopyrite) is not the same as in a newly formed synthetic compound in the river system due to an anthropogenic input (i.e. calcium arsenate). This illustrates the importance of the analysis of solid phases present in sediments because most of the polluting agents can be found in a different molecular configuration than the natural one. Copyright © 2008 John Wiley & Sons, Ltd.